Who are Philosophers from the Age of Enlightenment?

The Age of Enlightenment period of the Modern era of philosophy corresponds roughly to the 18th Century.

It includes the following major philosophers:

Berkeley, Bishop George (1685 – 1753) Irish
Voltaire (François Marie Arouet) (1694 – 1778) French
Hume, David (1711 – 1776) Scottish
Rousseau, Jean-Jacques (1712 – 1778) Swiss-French
Smith, Adam (1723 – 1790) Scottish
Kant, Immanuel (1724 – 1804) German
Burke, Edmund (1729 – 1797) Irish

In general terms, the Enlightenment was an intellectual movement, developed mainly in France, Britain and Germany, which advocated freedom, democracy and reason as the primary values of society. It started from the standpoint that men’s minds should be freed from ignorance, from superstition and from the arbitrary powers of the State, in order to allow mankind to achieve progress and perfection. The period was marked by a further decline in the influence of the church, governmental consolidation and greater rights for the common people. Politically, it was a time of revolutions and turmoil and of the overturning of established traditions.

The major philosophical movements of the period include British Empiricism, Rationalism and Kantianism. It also saw an increasing focus on Political Philosophy.

It was essentially a continuation of the process of rationalization begun in the Age of Reason of the 17th Century, but also to some extent a reaction against it, and the two periods are often combined as the Early Modern period.


Edmund Burke (1729 – 1797)


Edmund burkeEdmund Burke (1729 – 1797) was an Anglo-Irish philosopher, statesman and political theorist of the Age of Enlightenment.

He served for many years in the British House of Commons, and was one of the leading figures within the Conservative faction of the Whig party. He was a strong supporter of the American colonies, and a staunch opponent of the French Revolution. He is often regarded as the philosophical founder of Anglo-American Conservatism.


Burke was born in Dublin, Ireland on January 12, 1729. His father, Richard Burke, was a prosperous, professional solicitor, who had converted to the Church of Ireland from the Roman Catholicism of his Munster lineage. His mother, Mary (née Nagle), came from a genteel Roman Catholic family of County Cork. He was raised in the Church of Ireland (although his sister, Juliana, was brought up as and remained a Roman Catholic) and would remain throughout his life a practising Anglican, although his political enemies would later repeatedly accuse him of harbouring secret Catholic sympathies at a time when membership in the Catholic church would have disqualified him from public office.

His early education was at a Quaker school in Ballitore just south of Dublin, and he remained in correspondence with his schoolmate Mary Leadbeater, the daughter of the school’s owner, throughout his life. In 1744, he continued his education at Trinity College, Dublin, where he set up a debating club, known as Edmund Burke’s Club, and graduated in 1748. In 1750, he went to London to study law at the Middle Temple, but he soon gave up his legal studies in order to travel in Europe, and attempted to earn his livelihood through writing.

During his time in London, Burke published his first work, “A Vindication of Natural Society” (a defence of Anarchism) and a treatise on Aesthetics, “A Philosophical Enquiry into the Origin of Our Ideas of the Sublime and Beautiful”. He founded the influential political publication, the “Annual Register”, in 1858, and became closely connected with many of the leading intellectuals and artists of the time, including Samuel Johnson (1709 – 1784), David Garrick (1717 – 1779), Oliver Goldsmith (1730 -1774) and Joshua Reynolds (1723 – 1792).

In 1757, Burke married Jane Mary Nugent, and they had a son, Richard, in 1758 (another son, Christopher, died in infancy). From 1758 to 1761, they moved to Dublin, where Burke was private secretary to William Gerard Hamilton (1729 – 1796), who had been appointed Chief Secretary for Ireland. In 1765, he became private secretary to the Prime Minister of Great Britain, the liberal Whig Charles Watson-Wentworth, Marquess of Rockingham (1730 – 1782) and, in the same year, began his political career proper as Member of Parliament for Wendover.

He took a leading role in the debate over the constitutional limits to the executive authority of the King, and directly opposed King George III’s policy of severe sovereignty in relation to the American colonists. He campaigned against the persecution of Catholics in Ireland and denounced the abuses and corruption of the East India Company. His speeches and writings soon made him famous, and in 1774 he was elected MP for Bristol, then England’s “second city”, although his support for free trade with Ireland and his advocacy of Catholic emancipation were unpopular and he lost his seat in 1780. For the remainder of his parliamentary career, Burke sat as the member for Malton, a pocket borough of his benefactor, the Marquess of Rockingham. After Rockingham’s return to power, Burke became Paymaster of the Forces and Privy Councillor, although these ceased when Rockingham died unexpectedly in 1782.

With the beginning of the long Tory administration of William Pitt the Younger(1759 – 1806) in 1783, the remainder of Burke’s political life was in opposition, but he distinguished himself in the impeachment of the Indian governor Warren Hastings (1732 – 1818), and he vociferously condemned the French Revolution, which he predicted would end in disaster.

His strong views on the French Revolution received conflicting responses. Former admirers, such as Thomas Jefferson (1743 – 1826), Thomas Paine (1739 – 1809), Richard Brinsley Sheridan (1751 – 1816) and Charles James Fox (1749 – 1806), denounced Burke as a reactionary and an enemy of the French and their ground-breaking aspirations; other former supporters of the American Revolution, such as John Adams (1735 – 1826), George Washington (1732 – 1799) and Alexander Hamilton (1755 – 1804), however, agreed with Burke’s assessment of the French situation.

In 1794, his son Richard died and the Hastings trial came to an end, and Burke, feeling that his work was done and that he was worn out, retired from Parliament. Although he had regained the favour of King George III by his attitude on the French Revolution, he declined the title of Lord Beaconsfield, accepting only a generous pension instead. After a prolonged illness, Burke died on 9 July 1797 at Beaconsfield.


Burke’s first published work, “A Vindication of Natural Society” (subtitled “A View of the Miseries and Evils Arising to Mankind”), appeared in 1756. It was perhaps the first serious defence of Anarchism (although Burke later, with a government appointnent at stake, characterized it as a satire), and was taken quite seriously by later anarchists such as William Godwin (1756 – 1836).

In 1757, he published a treatise on Aesthetics, “A Philosophical Enquiry into the Origin of Our Ideas of the Sublime and Beautiful”, which attracted the attention of prominent Continental thinkers such as Denis Diderot (1713 – 1784) and Immanuel Kant.

In his “Reflections on the Revolution in France” of 1790, Burke described the French Revolution as a violent rebellion against tradition and proper authority, and as an experiment disconnected from the complex realities of human society. He vehemently disagreed with Jean-Jacques Rousseau‘s theory of the “Popular Will”, believing instead that most men in a nation are not qualified to govern it. He believed the country should look to men of finer upbringing and higher Christian education, or risk a move away from personal merit and distinction and towards an unprincipled, enervating mediocrity. The intemperate language and factual inaccuracies of the “Reflections” convinced many readers that Burke had lost his judgment but, after his death, when his predictions were proven largely correct, it grew to become his best-known and most influential work.

In economics, he was a strong supporter of the free market system (believing that trade should be fair and benefit both parties, but that governments should not interfere any more than necessary), but was wary of industrialization. The pioneering economist, Adam Smith, was a strong supporter of his ground-breaking views; the socialist Karl Marx was a radical opponent of them. Over time, Burke has come to be regarded as one of the fathers of modern Conservatism in the English-speaking world, and his thinking has exerted considerable influence over the political philosophy of modern classical Liberals.

A very common quotation mistakenly attributed to Burke is: “All that is necessary for the triumph of evil is that good men do nothing” (or several similar variations). There is no definite source for the quotation, but it may be a paraphrasing of Burke’s “When bad men combine, the good must associate; else they will fall one by one, an unpitied sacrifice in a contemptible struggle”.

Immanuel Kant (1724 – 1804)


Immanuel-KantImmanuel Kant (1724 – 1804) was a German philosopher of the Age of Enlightenment. He is regarded as one of the most important thinkers of modern Europe, and his influence on Western thought is immeasurable. He was the starting point and inspiration for the German Idealism movement in the late 18th and early 19th Centuries, and more specifically for the Kantianism which grew up around him in his own lifetime.

His works, especially those on Epistemology, Metaphysics and Ethics, such as his masterworks the “Critique of Pure Reason” and the “Critique of Practical Reason”, achieved a complete paradigm shift and moved philosophy beyond the debate between the Rationalists and Empiricists which had dominated the Age of Reason and the early Age of Enlightenment, and indeed to combine those two apparently contradictory doctrines.

His ideas and original thought have informed almost every philosophical movement since, and he continues to challenge and influence philosophy (in both the Analytic and Continental Philosophy camps) to this day.


Immanuel Kant was born on 22 April 1724 in the city of Königsberg (then the capital of Prussia, now modern-day Kaliningrad, Russia). He spent his entire life in and around his hometown, never travelling more than a hundred miles from Königsberg. His father, Johann Georg Kant, was a German craftsman and harness maker from Memel, Prussia; his mother, Anna Regina Porter, was born in Nuremberg, but was the daughter of a Scottish saddle and harness maker. He was the fourth of eleven children (five of whom reached adulthood). He was baptized as “Emanuel” but later changed his name to “Immanuel” after he learned Hebrew.

He was raised in a Pietist household (a strict Lutheran sect that stressed intense religious devotion, personal humility and a literal interpretation of the Bible), and accordingly received a strict, punitive and disciplinary education that favoured Latin and religious instruction over mathematics and science.

Kant’s elementary education was undertaken at Saint George’s Hospital School, after which he was educated at the Pietist Collegium Fredericianum, where he remained from 1732 until 1740, and where he studied theology and excelled in the classics. Kant showed great application to study early in his life, and was enrolled in the University of Königsberg in 1740, at the age of 16.

There, under the influence of a young instructor, Martin Knutzen, Kant became interested in philosophy, mathematics, and the natural sciences, and, through the use of Knutzen’s private library, grew familiar with the Rationalist philosophy of Gottfied Leibniz and Christian Wolff (1679 – 1754), as well as the natural philosophy and new mathematical physics of Sir Isaac Newton (1643 – 1727). Knutzen dissuaded the young scholar from traditional Idealism (i.e. the idea that reality is purely mental), which was negatively regarded by the whole philosophy of the 18th Century, and a chance reading of David Hume also raised his suspicions against Rationalism and he was soon to move away from his early Rationalist beliefs. He later admitted that reading Hume was what “first interrupted my dogmatic slumber”.

The death of Kant’s father in 1746 left him without income and interrupted his studies. For seven years, he worked as a private tutor in the smaller towns surrounding Königsberg, but he continued his scholarly research, and published several early works, mainly on scientific topics. 1749 saw the publication of his first philosophical work, “Gedanken von der wahren Schätzung der lebendigen Kräfte” (“Thoughts on the True Estimation of Living Forces”).

In 1755, he presented a Latin treatise, “On Fire”, to qualify for his doctoral degree, and he spent the next 15 years as a non-salaried lecturer at the University of Königsberg (dependent on fees from the students who attended his lectures). He lectured on Metaphysics, Logic, mathematics, physics and physical geography, and, despite a large teaching burden, continued to publish papers on various topics, including “Der einzig mögliche Beweisgrund zu einer Demonstration des Daseins Gottes” (“The Only Possible Argument in Support of a Demonstration of the Existence of God”) in 1763 and other works on Logic and Aesthetics. He finally achieved a professorship of Logic and Metaphysics at Königsberg in 1770, at the age of 46, an established scholar and an increasingly influential philosopher.

For the next decade, Kant published almost nothing, and applied himself to the vexing issues of the Philosophy of Mind and to a resolution of the contradictions inherent in perception and conception as explained by the Rationalists and Empiricists, resisting all his friends’ attempts to bring him out of his isolation.

The result was the “Kritik der reinen Vernunft” (“Critique of Pure Reason”) of 1781, now widely regarded one of the most important and difficult books in Western philosophical thought. However, this long (over 800 pages in the original German edition) and dense book, written in a somewhat convoluted style was largely ignored upon its initial publication, and Kant, who was by then quite a popular author, was dismayed. He wrote the “Prolegomena zu einer jeden künftigen Metaphysik” (“Prolegomena to any Future Metaphysics”) in 1783 as a summary and clarification of its main views, but it was only as a result of a series of widely read public letters on the Kantian philosophy published by Karl Reinholdin 1786, as a response to the the Pantheism Dispute (a central intellectual controversy of the time), that Kant’s reputation spread, making him the most famous philosopher of his era.

Undaunted by the negative initial response to his masterwork, Kant continued to publish papers throughout the 1780s, including a heavily revised second edition of the “Critique of Pure Reason”. He also continued to develop his moral philosophy, notably in 1785’s “Grundlegung zur Metaphysik der Sitten” (“Groundwork of the Metaphysics of Morals”), 1788’s “Kritik der praktischen Vernunft”(“Critique of Practical Reason”, known as the “second Critique”) and 1797’s “Metaphysik der Sitten” (“Metaphysics of Morals”). The 1790 “Kritik der Urteilskraft” (“Critique of Judgment”, the “third Critique”) applied the Kantian system to Aesthetics and teleology (the philosophical study of design and purpose).

By the 1790s, there were several journals devoted solely to defending and criticizing the Kantian philosophy. But, despite his success, philosophical trends were moving in another direction, and many of Kant’s most important disciples (including Karl Reinhold, Jakob Sigismund Beck and Johann Gottlieb Fichte) transformed the Kantian position into increasingly radical forms of Idealism, marking the emergence of the German Idealism movement. Kant opposed these developments and even publicly denounced Fichte in an open letter in 1799.

Kant continued writing until shortly before his death, although the Critiques remain the real sources of his influence. Only a life of extraordinary self-disciplineenabled him to accomplish his task: he kept to such a strict routine that the residents of Königsberg quite literally set their watches by his schedule. He never married, was barely 5 feet tall, and extremely thin, and his health was never robust, but he attributed his longevity and his prodigious output to his invariable daily routine. Contrary to his dour reputation, though, Kant was actually very sociable, a witty and amusing conversationalist, an elegant dresser, and his lectures at the University of Königsberg, where he taught for over 30 years, were famous for their brilliance.

Towards the end of his life, Kant became increasingly anti-social and bitter over the growing loss of his memory and capacity for work. He became totally blind and finally died on 12 February 1804 in the beloved Königsberg where he had spent his entire life. He was buried in Königsberg Cathedral.


Kant wrote a number of well-received and semi-popular essays on a variety of topics from science to history to religion to politics to anthropology, and by the 1770s he had become a popular author of some note, despite the difficulty and obscurity of his style. The philosophy for which he has become justifiably famous, though, dates largely from his middle and old age.

His first real philosophical work was 1749’s “Gedanken von der wahren Schätzung der lebendigen Kräfte” (“Thoughts on the True Estimation of Living Forces”), and he continued publishing books and papers for the rest of his life, although with an eleven-year gap betwen 1770 and 1781 leading up to the publication of his masterwork, “Kritik der reinen Vernunft” (“Critique of Pure Reason”). This and the two succeeding Critiques, 1788’s “Kritik der praktischen Vernunft” (“Critique of Practical Reason”) and 1790’s “Kritik der Urteilskraft” (“Critique of Judgment”), remain the real sources of his lasting influence.

In his Epistemology, Kant started with the traditional distinction between “truths of reason” (which Kant called analytic propositions, ones which are true simply by virtue of their meaning, and only elucidate or explain words e.g. “all bachelors are unmarried”) and “truths of fact” (which Kant called synthetic propositions, ones which make claims beyond that e.g. “all bachelors are happy”). He added to this two other concepts: a priori knowledge (which comes purely from reasoning, independent of experience, and typically applies to analytic propositions) and a posteriori knowledge (which comes from experience alone, and typically applies to synthetic propositions).

On the one hand, Empiricism allows for synthetic propositions and a posteriori knowledge, and, on the other hand, Rationalism allows for analytic propositions and a priori knowledge. However, Kant maintained that the two could be combined, and that synthetic a priori statements were in fact possible, that there existed propositions which applied to the physical world but were not derived from the world, but which were established simply by argument. He argued that knowledge comes from a synthesis of experience and concepts: without the senses, we would not become aware of any object, but without understanding and reason we would not be able to form any conception of it.

He maintained that, although space and time are given to us as a priori pure intuitions, we grasp reality and make sense of the world through a basic conceptual apparatus, which involves several categories of thought. He divided these categories into four groups of three: quantity (unity, plurality, totality); quality(reality, negation, limitation); relation (substance, cause, community) and modality(possibility, existence, necessity).

Perhaps Kant’s most original contribution to philosophy was the idea that it is the representation that makes the object possible, rather than the object that makes the representation possible. This introduced the human mind as an active originator of experience rather than just a passive recipient of perception, and placed the role of the human subject or knower at the centre of inquiry into our knowledge.

However, he also set limits to knowledge. He distinguished between appearance(the world of phenomena) and reality (the world of noumena). Although our senses tell us that things exist outside of ourselves, the actual real substance of an object (what he called the “ding-an-sich” or thing-in-itself”) was essentially unknowable. Thus, there may exist many things in the universe which we do not have the sensory or intellectual capacity to apprehend, and, although these things are real in themselves, they are not real “for us”. We have certain predispositionsas to what exists, and only those things that fit into these predispositons can be said to exist for us. This was something of a radical and revolutionary idea which does not seem to have occurred to anyone before Kant.

The (simplified) argument of the first “Critique”, then, is that, while empirical objects, like books and chairs, are in some sense very real, they might not be “transcendentally real”. Chairs are real insofar as they are objects that have to conform to our concepts, to our perceptual categories, but we cannot be sure that they are transcendentally real, because to be sure of this we would ourselves have to transcend our own perceptual limitations to confirm the “transcendental” existence of objects. Thus, “real objects”, in Kant’s view, are simply those that are subject to our perceptual categories: we cannot be sure that other non-empirical objects do not exist, but this should not worry us.

His doctrine of the “primacy of practical over pure reason”, led to the later 19th Century doctrine of Voluntarism. He argued that, intellectually, humans are incapable of knowing ultimate reality, but this need not (and, Kant argues, must not) interfere with the duty of acting as though the spiritual character of this reality were certain. Thus, while Kant freely admitted that Newtonian physics was a clear and accurate depiction of the world of appearances, the world we are able to physically perceive, there was still room in his system for other concepts completely (such as free will, rational agency, God, good and bad, etc), but that these concepts could not be subjects of definite knowledge.

Kant argued that, while reason can be a helpful tool, it must be properly controlled so that we do not unreflectively accept things for which we have no evidence. What he calls the “critical method” is a philosophical approach that allows people to discover which questions reason can answer, and which ones it cannot. Thus, in his 1793 “Religion innerhalb der Grenzen der bloßen Vernunft” (“Religion within the Boundaries of Mere Reason”), Kant again encouraged us to give up things we do not need, namely religious practices that are unnecessary for true moral conduct.

Similarly, although reason can help us supplant unjust political regimes with better ones, for example, Kant did not believe that reason is an unqualified good, but must be employed critically in order to avoid heading down the wrong path. Although he objected to direct democracy as “necessarily a despotism”, Kant foreshadowed Decmocratic Peace Theory in his 1795 essay “Zum ewigen Frieden” (“Perpetual Peace”), in which he posits that constitutional republicswere one of several necessary conditions for a perpetual peace. Unlike many Enlightenment thinkers, he argued that real democracy is not only humane, but also in keeping with the basic human desire to pursue collective ends.

Like many philosophers before (and after) him, Kant was deeply dissatisfied with the purported solutions of other philosophers to the perennial problem of how to reconcile the apparently deterministic character of the physical world with the existence of human free will, which was necessary for the resolution of moral and ethical questions. These contradictions seemed especially stark in the wake of the great leap forward in the physical sciences during the 17th Century, in which scientists seemed largely agreed on the new findings, as compared to the chaotic battlefield of philosophy, where no philosopher seemed able to agree with any other. He was also concerned with how a God could fit in with an essentially mechanical and determined universe, and he was eager to confront the serious doubts about philosophy as an intellectual enterprise that the skepticism of David Hume had recently sown in the philosophical community as a whole.

Kant developed his moral philosophy in three main works: “Grundlegung zur Metaphysik der Sitten” (“The Fundamental Principles of the Metaphysics of Ethics”: 1785), “Kritik der praktischen Vernunft” (“Critique of Practical Reason”: 1788), and “Metaphysik der Sitten” (“Metaphysics of Morals”: 1797). He started by observing that it is an observable empirical fact that people do in fact have moral and ethical views and, for them to have any meaning at all, people must have some element of free will.

His view of Ethics is deontological (i.e. it focuses on the rightness or wrongness of the actions themselves, as opposed to the rightness or wrongness of the consequences of those actions or the character of the actor, and holds that ethical rules bind people to an ethical duty). It is founded on his view of rationality as the ultimate good, and his belief that all people are fundamentally rational beings. He believed that morality was derived from rationality and that, just as rational thought leads us to an objective reality, it also leads us to an objective morality, which could be rationally supported.

His major contribution to Ethics was the theory of the Categorical Imperative, an absolutely universal, non-negotiable moral law which holds up regardless of context. At its simplest, it states that one should act only in such a way that you would want your actions to become a universal law, applicable to everyone in a similar situation (a kind of Moral Universalism or Moral Absolutism). Additionally, one must strive to treat others not as mere means, but as ends in themselves, so that (in stark contrast to Utilitarianism) it can never be right to manipulate, abuse or lie to individuals, even in the interests of others or even the perceived greater good. This latter maxim was, and remains, highly controversial when taken to extremes, but Kant insisted that it should remain sacrosanct. He asserted that each person is his own moral agent, and we should only be responsible for our own actions, not those of others.

According to Kant’s “critical method”, as described above, any attempts to prove God’s existence are necessarily a waste of time, because our concepts only work properly in the empirical world and God is, by definition, a non-empirical entity. However, he justifies his own faith by arguing that, although it would be superstitious or irrational to have a belief on something which can actually be empirically proven or demonstrated, it is not irrational to have a belief on something that clearly cannot be proven either way (like the existence of God). This amounts to a kind of Fideism.

This, however, is very different from Kant’s early metaphysical arguments in his pre-critical period. In his 1763 “Der einzig mögliche Beweisgrund zu einer Demonstration des Daseins Gottes” (“The Only Possible Argument in Support of a Demonstration of the Existence of God”), he first questionsboth the ontological argument and the argument from design for the existence of God (see the section on the Philosophy of Religion), before proposing his own solution (sometimes called the Kantian Moral Argument), that moral behaviour would only be rational in our manifestly unfair world if there is a next life in which justice is administered.

Kant produced an early treatise on Aesthetics, “Beobachtungen über das Gefühl des Schönen und Erhabenen” (“Observations on the Feeling of the Beautiful and Sublime”: 1763), and did not write on the subject again until the end of his career, in the “Kritik der Urteilskraft” (“Critique of Judgment”: 1790). He claimed that judgments of taste are both subjective and universal: subjective in that they are responses of pleasure, and do not essentially involve any claims about the properties of the object itself; universal in that they are not merely personal, but must in a crucial way be disinterested. He divided the kinds of aesthetic response into those of the Beautiful (a pleasure in order, harmony, delicacy and the like) and the Sublime (a response of awe before the infinite or the overwhelming).

Although less well known, Kant also wrote on the sciences throughout his life. In an early scientific paper entitled “Allgemeine Naturgeschichte und Theorie des Himmels” (“General Natural History and Theory of the Heavens”) of 1755, Kant postulated the origin of the solar system as a result of the gravitational interaction of atoms, anticipating Pierre-Simon Laplace’s hypothesis by more than 40 years. He also correctly deduced that the Milky Way was a large disk of stars, which he theorized was also formed from a much larger spinning cloud of gas.

Adam Smith (1723 – 1790)


Adam smithAdam Smith (1723 – 1790) was a Scottish philosopher and political economist of the Age of Enlightenment and a key figures in the Scottish Enlightenment.

He is widely cited as the father of modern economics, and sometimes as the father of modern Capitalism, and his magnum opus, “The Wealth of Nations”, is considered the first modern work of classical economics. His metaphor of the invisible hand of the free market has been of untold influence in the development of laissez faire economics and modern Capitalism and Individualism, but Smith’s work has been almost as influential in other areas of Political Philosophy, including Utilitarianism, Liberalism, Libertarianism, Socialism and Marxism.


Smith was born in early June 1723 in Kirkcaldy, Scotland. The exact date of his birth is unknown, but we known that he was baptized on 16 June 1723 (or 5 June in the old style Julian calendar). His father, also named Adam Smith, was a lawyer and civil servant, who died six months before Smith’s birth; his mother was Margaret Douglas. Few events from his early childhood are known, although he was reputedly abducted by gypsies at the age of four and eventually released without harm.

In the absence of his father, Smith was particularly close to his mother, and it was likely she who encouraged him to pursue his scholarly ambitions. He attended the well-regarded Burgh School of Kirkcaldy from 1729 to 1737, studying Latin, mathematics, history and writing. He entered the University of Glasgow when he was fourteen and studied Moral Philosophy under Francis Hutcheson (1694 – 1746), himself one of the founding fathers of the Scottish Enlightenment, and it was there that he developed an early passion for liberty, reason and free speech.

In 1740, he was awarded the Snell Exhibition Scholarship to attend Balliol College, Oxford, although he considered the teaching at Glasgow to be far superiorto that at Oxford, and he found his Oxford experience intellectually stifling (he was apparently punished at one point for being caught reading David Hume‘s “Treatise on Human Nature”). Although he did avail himself of Oxford’s excellent library, his time in Oxford was not a happy one, and at one point he developed shaking fits(perhaps symptoms of a nervous breakdown) and left the University in 1746, before his scholarship ended. He had originally intended to study theology and enter the clergy, but his subsequent learning (especially from the skeptical writings of David Hume), persuaded him to take a different route.

Smith began delivering public lectures (including his first pronouncements on “natural liberty”) in Edinburgh in 1748, under the patronage of Lord Kames (1696 – 1782). He also met the Scottish philosopher David Hume in 1750, and the two discovered much in common in their views, and were to share a close intellectual alliance and friendship. Smith had rejected Christianity while at Oxford, and it is generally believed that he returned to Scotland as a Deist, although religion was not an important part of his life, and he even had a grudging repect for Hume’s Atheism.

In 1751, Smith earned a professorship at Glasgow University, teaching Logic courses at first. The next year, he took over the University’s vacant Chair of Moral Philosophy, lecturing on Ethics, rhetoric, jurisprudence and political economy. He retained the position for the next thirteen years, among the busiest and happiest years of his life. He published his “The Theory of Moral Sentiments”in 1759 (based on his Glasgow lecture notes), and its popularity attracted students from home and abroad. The University of Glasgow conferred on Smith the title of Doctor of Laws (LL.D.) in 1762, but he nevertheless took up a lucrative offer to tutor the young Henry Scott, Duke of Buccleuch, and so resigned from the University at the end of 1763.

His new tutoring job entailed touring Europe with his charge, including trips to Toulouse, France (where they stayed for a year and a half) and then Geneva, Switzerland (where he met with the philosopher Voltaire), and then Paris (where he came to know intellectual leaders such as Benjamin Franklin, Anne-Robert-Jacques Turgot, Jean D’Alembert, André Morellet, Claude Adrien Helvétius and Francois Quesnay). Quesnay and Turgot were Physiocratics (a school of thought opposed to the dominant mercantilist tradition, which believed that wealth came from production and not from the attainment of precious metals, and from agriculture rather than merchants and manufacturers) and, while Smith did not embrace all of the physiocrats ideas, he considered it the nearest approximation to the truth then available.

After Henry Scott’s younger brother died in Paris in 1766, Smith’s tour as a tutor ended, and he returned home to Kirkcaldy, where he devoted much of the next ten years to his magnum opus, “The Wealth of Nations”, published in 1776. The book was an instant success, selling out the first edition in only six months, and in 1773 Smith was elected a fellow of the Royal Society of London, and then a member of the Literary Club two years later. In 1778, he was appointed to a post as Commissioner of Customs in Scotland, and he went to live with his mother in Edinburgh. In 1783, he became one of the founding members of the Royal Society of Edinburgh, and from 1787 to 1789 he occupied the honorary position of Lord Rector of the University of Glasgow.

Smith never married, and was looked on by people who knew him as an eccentricbut benevolent intellectual, comically absent-minded, with a habit of talking to himself. He was also an odd-looking character, with a large nose, bulging eyes, a protruding lower lip, a nervous twitch and a speech impediment.

After a painful illness, Smith died in Edinburgh on 17 July 1790, and was buried in the Canongate Kirkyard. On his death bed, he expressed regret that he had not achieved more. From the many notes and unpublished materials he left behind, a “History of Astronomy” and the “Essays on Philosophical Subjects” were published posthumously in 1795.



Smith published a large body of works throughout his life, beginning with his first book, “The Theory of Moral Sentiments”, written in 1759, and ending with the “Essays on Philosophical Subjects” which was published posthumously in 1795. His single most important book, though, was undoubtedly “The Wealth of Nations” (full title “An Inquiry Into the Nature and Causes of the Wealth of Nations”), published in 1776 and widely considered one of the most influential books on economics of all time.

“The Theory of Moral Sentiments” was Smith’s first published work, but he himself considered it his most important, and he continued to revise the work throughout his life, making extensive revisions to the final (6th) edition shortly before his death in 1790. It provided the ethical, philosophical, psychological and methodological underpinnings to his later works, and it was actually in this work that Smith first referred to the “invisible hand” to describe the apparent benefits to society of people behaving in their own interests.

In the book, he critically examined the moral thinking of the time, with the aim of explaining how mankind can form moral judgements in spite of its natural inclination toward self-interest. He concluded that conscience arises from social relationships, and proposed a theory of “sympathy” in which the act of observing others makes people aware of themselves and of the morality of their own behaviour. While at first glance this Altruism seems to contradict the Egoism and Individualism found in his later works (the so-called “Adam Smith Problem”), it should be noted that he was also suggesting that individuals would actually find it in their own self-interest to develop this sympathy.

“An Inquiry Into the Nature and Causes of the Wealth of Nations”, published in 1776, is a clearly written account of political economy at the dawn of the Industrial Revolution, and is widely considered to be the first and most influential modern work of economics. In it, he expands on three main concepts that together form the foundation of free market economics and Capitalism: the division of labour, the pursuit of self interest and freedom of trade.

He argued in the “Wealth of Nations” that, while human motives are often selfishness and greed, the competition in the free market would tend to benefit society as a whole by keeping prices low, while still building in an incentive for a wide variety of goods and services (“the study of his own advantage naturally, or rather necessarily, leads him to prefer that employment which is most advantageous to the society”). He further argued that a division of labour would effect a great increase in production and that, although the free market appears chaotic and unrestrained, it is actually guided to produce the right amount and variety of goods by a so-called “invisible hand” (the same analogy in a different form).

Jean-Jacques Rousseau (1712 – 1778)


-Jean-Jacques_RousseauJean-Jacques Rousseau (1712 – 1778) was a French philosopher and writer of the Age of Enlightenment.

His Political Philosophy, particularly his formulation of social contract theory (or Contractarianism), strongly influenced the French Revolution and the development of Liberal, Conservative and Socialist theory. A brilliant, undisciplined and unconventional thinker throughout his colourful life, his views on Philosophy of Education and on religion were equally controversial but nevertheless influential.

He is considered to have invented modern autobiography and his novel “Julie, ou la nouvelle Héloïse” was one of the best-selling fictional works of the 18th Century (and was important to the development of Romanticism). He also made important contributions to music, both as a theorist and as a composer.


Rousseau was born on 28 June 1712 in Geneva, Switzerland (although he spent most of his life in France, he always described himself as a citizen of Geneva). His mother, Suzanne Bernard, died just nine days after his birth from birth complications. His father, Isaac Rousseau, a failed watchmaker, abandoned him in 1722 (when he was just 10 years old) to avoid imprisonment, after which time Rousseau was cared for by an uncle who sent him to study in the village of Bosey. His only sibling, an older brother, ran away from home when Rousseau was still a child.

His childhood education consisted solely of reading the Plutarch’s “Lives” and Calvinist sermons in a public garden. His youthful experiences of corporal punishment at the hands of the pastor’s sister developed in later life into a predilection for masochism and exhibitionism. For several years as a youth, he was apprenticed to a notary and then to an engraver.

In 1728, at the age of 16, Rousseau left Geneva for Annecy in south-eastern France, where he met Françoise-Louise de Warens, a French Catholic baroness. She later became his lover, but she also provided him with the education of a nobleman by sending him to a good Catholic school, where Rousseau became familiar with Latinand the dramatic arts, in addition to studying Aristotle. During this time he earned money through secretarial, teaching and musical jobs.

In 1742, he moved to Paris with the intention of becoming a musician and composer. He presented his new system of numbered musical notation to the Académie des Sciences but, although ingenious and compatible with typography, the system was rejected.

He was secretary to the French ambassador in Venice for 11 months from 1743 to 1744, although he was forced to flee to Paris to avoid prosecution by the Venetian Senate (he often referred to the republican government of Venice in his later political work). Back in Paris, he befriended and lived with Thérèse Levasseur, a semi-literate seamstress who bore him five children all of whom were left at the Paris orphanage soon after birth.

Towards the end of the 1740s, he became friends with the French philosopher Denis Diderot (1713 – 1784) and contributed several articles to the latter’s “Encyclopédie”. However, the friendship soon became strained and Diderot later described Rousseau as being “deceitful, vain as Satan, ungrateful, cruel, hypocritical and full of malice”.

His 1750 “Discours sur les Sciences et les Arts” (“Discourse on the Arts and Sciences”) won him first prize in an essay competition (on whether or not the development of the arts and sciences had been morally beneficial, to which Rousseau had answered in the negative) and gained him significant fame. He also continued his interest in music and his popular opera “Le Devin du Village” (“The Village Soothsayer”) was performed for King Louis XV in 1752. He was outspoken in his defence of Italian music against the music of popular French composers such as Jean-Philippe Rameau (1683 – 1764). In 1754, he returned to Geneva where he re-converted to Calvinism and regained his official Genevan citizenship.

In 1755, Rousseau completed his second major work, the “Discours sur l’origine et les fondments de l’inegalite” (“Discourse on the Origin and Basis of Inequality Among Men”, usually known as the “Discourse on Inequality”), which was widely read and further solidified Rousseau’s place as a significant intellectual figure. However, it also caused him to gradually become estranged from his former friends such as Diderot and the Baron von Grimm and from benefactors such as Madame d’Epinay, although he continued to enjoy the support and patronage of one of the wealthiest nobles in France, the Duc de Luxembourg. In 1761, Rousseau published the successful romantic novel “Julie, ou la nouvelle Héloïse” (“Julie, or The New Heloise”).

In 1762, he published two major books, “Du Contrat Social, Principes du droit politique” (“The Social Contract, Principles of Political Right”) in April and then “Émile, ou de l’Éducation (or “Émile, or On Education”) in May. The books criticized religion and were banned in France and Geneva, and Rousseau was forced to flee. He made stops in Bern, Germany and in Môtiers, Switzerland, where he enjoyed for a time the protection of Frederick the Great of Prussia and his local representative, Lord Keith. However, when his house in Môtiers was stoned in 1765, he took refuge in England with the philosopher David Hume, although he soon began to experience paranoid fantasies about plots against him involving Hume and others.

He returned to the southeast of France, incognito and under a false name, in 1767. The following year, he went through a legally invalid marriage to his mistress Thérèse, and in 1770 he was finally allowed to return to Paris. One of the conditionsof his return was that he was not allowed to publish any books, but after completing his “Confessions”, Rousseau began private readings in 1771. He was ordered to stop by the police, and the “Confessions” was only partially published in 1782, four years after his death (all his subsequent works were only to appear posthumously).

His latter years were largely spent in deliberate withdrawal, although he continued to write, including the “Considérations sur le gouvernement de Pologne”(“Considerations on the Government of Poland”), “Rousseau: juge de Jean-Jacques” (“Rousseau: Judge of Jean-Jacques”) and “Les Rêveries du promeneur solitaire” (“Reveries of the Solitary Walker”), supporting himself by copying music.

Rousseau died on 2 July 1778 of a hemorrhage while taking a morning walk on the estate of the Marquis de Giradin at Ermenonville, near Paris. Sixteen years later, his remains were moved to the Panthéon in Paris (across from those of his contemporary, Voltaire).


Rousseau saw a fundamental divide between society and human nature and believed that man was good when in the state of nature (the state of all other animals, and the condition humankind was in before the creation of civilization), but has been corrupted by the artificiality of society and the growth of social interdependence. This idea of the natural goodness of humanity has often led to the attribution the idea of the “noble savage” to Rousseau, although he never used the expression himself and it does not adequately render his idea.

He did not, however, imply that humans in the state of nature necessarily acted morally (in fact, terms such as ‘justice’ or ‘wickedness’ are simply inapplicable to pre-political society as Rousseau understood it). For Rousseau, society’s negative influence on men centers on its transformation of “amour de soi” (a positive self-love which he saw as the instinctive human desire for self-preservation, combined with the human power of reason) into “amour-propre” (a kind of artificial pridewhich forces man to compare himself to others, thus creating unwarranted fear and allowing men to take pleasure in the pain or weakness of others).

In “Discourse on the Arts and Sciences” (1750) Rousseau argued that the arts and sciences had not been beneficial to humankind because they were not human needs, but rather a result of pride and vanity. Moreover, the opportunities they created for idleness and luxury contributed to the corruption of man, undermined the possibility of true friendship (by replacing it with jealousy, fear and suspicion), and made governments more powerful at the expense of individual liberty.

His subsequent “Discourse on Inequality” (1755) expanded on this theme and tracked the progress and degeneration of mankind from a primitive state of nature to modern society in more detail, starting from the earliest humans (solitary beings, differentiated from animals by their capacity for free will and their perfectibility, and possessed of a basic drive to care for themselves and a natural disposition to compassion or pity). Forced to associate together more closely by the pressure of population growth, man underwent a psychological transformation and came to value the good opinion of others as an essential component of their own well-being, which led to a golden age of human flourishing (with the development of agriculture, metallurgy, private property and the division of labour) but which also led to inequality.

Rousseau concluded from his analysis of inequality that the first state was invented as a kind of social contract, but a flawed one made at the suggestion of the rich and powerful to trick the general population and institute inequality as a fundamental feature of human society. In “The Social Contract” of 1762 (his most important work and one of the most influential works of Political Philosophy in the Western tradition), he offered his own alternative conception of the social contract. Opening with the dramatic lines, “Man is born free, and everywhere he is in chains. One man thinks himself the master of others, but remains more of a slave than they”, Rousseau claimed (contrary to his earlier work) that the state of nature was a primitive and brutish condition, without law or morality, which humans deliberately left for the benefits and necessity of cooperation.

He argued that, by joining together into civil society through the social contractand abandoning their claims of natural right, individuals can both preserve themselves and yet remain free, because submission to the authority of the general will of the people as a whole guarantees individuals against being subordinated to the wills of others, and also ensures that they themselves obey because they are (collectively) the authors of the law. It should be noted that Rousseau was bitterly opposed to the idea that the people should exercise sovereignty via a representative assembly; rather, he held that they should make the laws directly, which would effectively prevent the ideal state from becoming a large society, such as France was at the time.

Rousseau’s views on religion were highly controversial. His view that man is good by nature conflicted with the doctrine of original sin, and his theology of nature(as well as the claims he made in “The Social Contract” that true followers of Jesus would not make good citizens) led to the condemnation and banning of his books in both Calvinist Geneva and Catholic Paris.

Rousseau was one of the first modern writers to seriously attack the institution of private property, and therefore is considered to some extent a forebear of modern Socialism, Marxism and Anarchism. He also questioned the assumption that the will of the majority is always correct, arguing that the goal of government should be to secure freedom, equality and justice for all within the state, regardless of the will of the majority.

Rousseau set out his influential views on Philosophy of Education in his semi-fictitious “Émile” (1762). The aim of education, he argued, is to learn how to live righteously, and this should be accomplished by following a guardian (preferably in the countryside, away from the bad habits of the city) who can guide his pupil through various contrived learning experiences. He minimized the importance of book learning and placed a special emphasis on learning by experience, and he recommended that a child’s emotions should be educated before his reason. He took the subordination of women as read, however, and envisaged a very different educational process for women, who were to be educated to be governed rather than to govern.

David Hume (1711 – 1776)


David humeDavid Hume (1711 – 1776) was a Scottish philosopher, economist and historian of the Age of Enlightenment. He was an important figure in the Scottish Enlightenment and, along with John Locke and Bishop George Berkeley, one of the three main figureheads of the influential British Empiricism movement.

He was a fierce opponent of the Rationalism of DescartesLeibniz and Spinoza, as well as an atheist and a skeptic. He has come to be considered as one of the most important British philosophers of all time, and he was a huge influence on later philosophers, from Immanuel Kant and Arthur Schopenhauer to the Logical Positivists and Analytic Philosophers of the 20th Century, as well as on intellectuals in other fields (including Albert Einstein, who claimed to have been inspired by Hume’s skepticism of the established order).

Even today, Hume’s philosophical work remains refreshingly modern, challenging and provocative. In later life, however, he largely turned away from philosophy in favour of economics and his other great love, history, and it was only then that he achieved recognition in his own lifetime.


Hume was born on 26 April 1711 in a tenement on the Lawnmarket in Edinburgh, Scotland. His father was Joseph Home (an advocate or barrister of Chirnside, Berwickshire, Scotland), and the aristocrat Katherine Lady Falconer. He changed his name to Hume in 1734 because the English had difficulty pronouncing “Home” in the Scottish manner.

He was well read, even as a child, and had a good grounding in Greek and Latin. He attended the University of Edinburgh at the unusually early age of twelve (possibly as young as ten), although he had little respect for the professors there and soon threw over a prospective career in law in favour of philosophy and general learning. At the tender age of eighteen, he made a great “philosophical discovery” (which remains somewhat unexplained and mysterious) that led him to devote the next ten years of his life to a concentrated period of study, reading and writing, almost to the verge of a nervous breakdown.

In order to earn a living, he took a position in a merchant’s office in Bristol before moving to Anjou, France in 1734. It was there that he used up his savings to support himself while he wrote his masterwork, “A Treatise of Human Nature”, which he completed in 1737 (at only 26 years of age). Despite the disappointment of the work’s poor reception in Britain (it was considered “abstract and unintelligible”), he immediately set to work to produce an anonymous “Abstract” or shortened version of it.

After the publication of his “Essays Moral and Political” in 1744, Hume was refused a post at the University of Edinburgh after local ministers petitioned the town council not to appoint Hume due to his Atheism. For about a year he tutored the unstable Marquise of Annandale and became involved with the Canongate Theatre in Edinburgh, where he associated with some of the Scottish Enlightenment luminaries of the time.

From 1746, Hume served for three years as Secretary to a distant relative, Lieutenant-General St. Clair, including as an aide-de-camp on diplomatic missions in Austria and Northern Italy, and even at one point as a staff officer on an ill-fated military expedition as part of the War of the Austrian Succession. It was during this period that he wrote his “Philosophical Essays Concerning Human Understanding”, later published as “An Enquiry Concerning Human Understanding”, which proved little more successful than the “Treatise”. He was charged with heresy (although he was defended by his young clerical friends, who argued that, as an atheist, he was outside the Church’s jurisdiction), and was again deliberately overlooked for the Chair of Philosophy at the University of Glasgow.

In 1752, the Faculty of Advocates employed him as their librarian, for which he received little or no emolument, but which gave him access to a large library, and which enabled him to continue historical research for his “History of Great Britain”. This enormous work, begun in 1745 and not completed until 1760, ran to over a million words and traced events from the Saxon kingdoms to the Glorious Revolution. It was a best-seller in its day and became the standard work on English history for many years. Thus, it was as a historian that Hume finally achieved literary fame.

From 1763 to 1765, Hume was Secretary to Lord Hertford in Paris, where he was admired by Voltaire and was friends (briefly) with Jean-Jacques Rousseau. For a year from 1767, he held the appointment of Under Secretary of State for the Northern Department in London, before retiring back to Edinburgh in 1768.

He died in Edinburgh on 25 August 1776, aged 65, probably as a result of a debilitating cancer he suffered from in his latter years, and was buried, as he requested, on Calton Hill, overlooking his home in the New Town of Edinburgh. He remained to the end positive and humane, well-loved by all who knew him, and he retained great equanimity in the face of his suffering and death.


Most of Hume’s philosophical work dates from his earlier years, in particular stemming from a mysterious intellectual revelation he appears to have experienced at the age of just eighteen. He spent most of the next ten years frantically trying to capture these thoughts on paper, resulting in “A Treatise of Human Nature”which he completed in 1737 at the age of just 26 (and published two years later). This book, which he subtitled “An Attempt to Introduce the Experimental Method of Reasoning into Moral Subjects”, is now consider to be Hume’s most important work and one of the most important books in the whole of Western philosophy, despite its poor initial reception. He refined the “Treatise” in the later “Philosophical Essays Concerning Human Understanding” (actually published as “An Enquiry Concerning Human Understanding” in 1748), along with a companion volume “An Enquiry Concerning the Principles of Morals”(1751), although these publication proved hardly more successful than the original “Treatise” on which they were based.

Hume was a thorough-going Empiricist, the last chronologically of the three great British Empiricists of the 18th Century (along with John Locke and Bishop George Berkeley), and the most extreme. He believed that, as he put it, “the science of manis the only solid foundation for the other sciences”, that human experience is as close are we are ever going to get to the truth, and that experience and observation must be the foundations of any logical argument. Anticipating the Logical Positivist movement by almost two centuries, Hume was essentially attempting to demonstrate how ordinary propositions about objects, causal relations, the self, etc, are semantically equivalent to propositions about one’s experiences.

He argued that all of human knowledge can be divided into two categories: relations of ideas (e.g. mathematical and logical propositions) and matters of fact(e.g. propositions involving some contingent observation of the world, such as “the sun rises in the East”), and that ideas are derived from our “impressions” or sensations. In the face of this, he argued, in sharp contradistinction to the French Rationalists, that even the most basic beliefs about the natural world, or even in the existence of the self, cannot be conclusively established by reason, but we accept them anyway because of their basis in instinct and custom, a hard-line Empiricist attitude verging on complete Skepticism.

But Hume’s Empiricism and Skepticism was mainly concerned with Epistemology and with the limits of our ability to know things. Although he would almost certainly have believed that there was indeed an independently existing world of material objects, causally interacting with each other, which we perceive and represent to ourselves through our senses, his point was that none of this could be actually proved. He freely admitted that we can form beliefs about that which extends beyond any possible experience (through the operation of faculties such as custom and the imagination), but he was entirely skeptical about any claims to knowledge on this basis.

Central to grasping Hume’s general philosophical system is the so-called “problem of induction”, and exactly how we are able to make inductive inferences (reasoning from the observed behaviour of objects to their behaviour when unobserved). He noted that humans tend to believe that things behave in a regular manner, and that patterns in the behaviour of objects will persist into the future and throughout the unobserved present (an idea sometimes called the Principle of the Uniformity of Nature). Hume argued forcefully that such a belief cannot be justified, other than by the very sort of reasoning that is under question (induction), which would be circular reasoning. Hume’s solution to this problem was to argue that it is natural instinct, rather than reason, that explains our ability to make inductive inferences, and many have seen this as a major contribution to Epistemology and the theory of knowledge.

Hume was a great believer in the scientific method championed by Francis Bacon, Galileo Galilei (1564 – 1642) and Sir Isaac Newton (1643 – 1727). However, the application of the problem of induction to science suggests that all of science is actually based on a logical fallacy. The so-called induction fallacy states that, just because something has happened in the past, it cannot be assumed that it will happen again, no matter how often it seems to happen. However, this is exactly what the scientific method is built on, and Hume was forced to conclude, rather unsatisfactorily, that even though the fallacy applies, the scientific method appears to work.

Closely linked to the problem of induction is the notion of causality or causation. It is not always clear how we know that something is actually caused by another thing and, although day always follows night and night day, there is still no causal link between them. Hume concluded that it is the mental act of association that is the basis of our concept of causation (although different commentators differ in their interpretation of Hume’s words on the matter, varying from a logical positivist interpretation to a skeptical realist or quasi-realist position).

Hume’s views on personal identity arose from a similar argument. For Hume, the features or properties of an object are all that really exist, and there is no actual object or substance of which they are the features. Thus, he argued, an apple, when stripped of all its properties (colour, size, shape, smell, taste, etc), is impossible to conceive of and effectively ceases to exist. Hume believed that the same argument applied to people, and he held that the self was nothing but a bundle or collection of interconnected perceptions linked by the properties of constancy and coherence, a view sometimes known as “bundle theory”, and one in direct opposition to Descartes‘s “I think therefore I am” assertion.

Hume’s anti-Rationalism, however, was not confined to his theory of belief and knowledge, but also extended into other spheres, including Ethics. He asserted that “reason is, and ought only to be, the slave of the passions, and can never pretend to any other office than to serve and obey them”. Thus, he severely circumscribed reason’s role in the production of action, and stressed that desires are necessary for motivation, and this view on human motivation and action formed the cornerstone of his ethical theory. He conceived moral or ethical sentiments to be intrinsically motivating, and to be the providers of reasons for action. Thus, he argued, given that one cannot be motivated by reason alone (given that motivation requires the additional input of the passions), then reason cannot be behind morality. His theory of Ethics, sometimes described as sentimentalism, has helped to inspire various forms of non-cognitivist and moral nihilist ethical theories including emotivism, ethical expressivism, quasi-realism, error theory, etc.

In his “A Treatise of Human Nature”, Hume definitively articulated the so-called “is-ought problem”, which has since become so important in Meta-Ethics, noting that claims are often made about what ought to be on the basis of statements about what is. However, Hume pointed out, there are significant differences between descriptive statements (about what is) and prescriptive or normative statements (about what ought to be), and it is not at all obvious how we can get from making descriptive statements to prescriptive. In line with his ingrained Skepticism, he advised extreme caution against making such inferences, and this complete severing of “is” from “ought” is sometimes referred to as “Hume’s Guillotine”.

As an Empiricist, Hume was always concerned with going back to experience and observation, and this led him to touch on some difficult ideas in what would later become known as the Philosophy of Language. For instance, he was convinced that for a word to mean anything at all, it had to relate to a specific idea, and for an idea to have real content it had to be derived from real experience. If no such underlying experience can be found, therefore, the word effectively has no meaning. In fact, he drew a distinction between thinking (which concerns clear ideas which have a real source in experience) and just everyday talking (which often uses confused notions with no real foundation in experience).

This reasoning also led him to develop what has become known as “Hume’s Fork”. For any new idea or concept under consideration, he said, we should always ask whether it concerns either a matter of fact (in which case one should then ask whether it is based on on observation and experience), or the relation between ideas (e.g. mathematics or Logic). If it is neither, then the idea has no value and no real meaning and should be discarded.

Like Thomas Hobbes before him, Hume sought to reconcile human freedom with the mechanist (or determinist) belief that human beings are part of a deterministic universe whose happenings are governed by the laws of physics. Hume’s reconcilation of freedom and determinism (a position known as compatibilism) involves a more precise definition of Liberty (“a power of acting or not acting, according to the determinations of the will”) and Necessity (“the uniformity, observable in the operations of nature; where similar objects are constantly conjoined together”), and the argued conclusion that not only are the two compatible, but that Liberty actually requires Necessity. Furthermore, he argued that, in order to be held morally responsible, it is required that our behaviour be caused or necessitated.

Hume wrote a great deal on religion, although, due to the rather repressive religious climate of the day, he deliberately constrained his words (as it was, the Church of Scotland seriously considered bringing charges of infidelity against him). He never openly declared himself to be an atheist, and did not acknowledge his authorship of many of his works in this area until close to his death (and some were not even published until afterwards).

However, it is certainly true that, in works such as “An Enquiry concerning Human Understanding” (1748) and “Dialogues Concerning Natural Religion” (written between about 1750 and his death in 1776, and published posthumously in 1779), he attacked many of the basic assumptions of religion and Christian belief, and he found the idea of a God effectively nonsensensical, because there was no way of arriving at the idea through sensory data. Some consider it his best work, and many of his arguments have become the foundation of much of the succeeding secular thinking about religion. Having said that, though, it is likely that Hume was, true to his most basic inclinations, skeptical both about religious belief (at least as demanded by the religious organizations of his time) and of the complete Atheism of such contemporaries as Baron d’Holbach (1723 – 1789), and his position may best be characterized by the term “irreligious”.

Hume argued that it is impossible to deduce the existence of God from the existence of the world because causes cannot be determined from effects. Although he left open the theoretical possibility of miracles (which may be defined as singular events that differ from the established laws of Nature), he cautioned that they should only be believed if it were less likely that the testimony was false than that a miracle did in fact occur, and offered various arguments against this ever having actually happened in history.

He gave the classic criticism of the teleological argument for the existence of God (also known as the argument from design, that order and apparent purpose in the world bespeaks a divine origin – see the Arguments for the Existence of God section of the Philosophy of Religion page for more details), arguing that, for the design argument to be feasible, it must be true that order and purpose are observed only when they result from design (whereas, on the contrary, we see order in presumably mindless processes like the generation of snowflakes and crystals). Furthermore, he argued that the design argument is based on an incomplete analogy (that of the universe to a designed machine), and that to deduce that our universe is designed, we would need to have an experience of a range of different universes. Even if the design argument were to be successful, he questioned why we should assume that the designer is God, and, if there is indeed a designer god, then who designed the designer? Also, he asked, if we could be happy with an inexplicably self-ordered divine mind, why should we not rest content with an inexplicably self-ordered natural world?

When faced with Leibniz‘s contention that the only answer to the question “why is there something rather than nothing?” was God, and that God was a necessary being with no need of explanation, Hume responded that there was no such thing as a necessary being, and that anything that could be conceived of as existent could just as easily be conceived of as non-existent. However, he was not willing to propose a convincing alternative answer to the riddle of existence, taking refuge in the argument that any answer to such a question would be necessarily meaningless, as it could never be grounded in our experience.

Hume’s Political Philosophy is difficult to pinpoint, as his work contains elements of both Conservatism and Liberalism, and he resisted aligning himself with either of Britain’s two political parties, the Whigs and the Tories. His central concern was to show the importance of the rule of law, and stressed, in his “Essays Moral and Political” of 1742, the importance of moderation in politics (particularly within the turbulent historical context of 18th Century Scotland). In general, he thought that republics were more likely than monarchies to administer laws fairly, but the important point for Hume was that society be governed by a general and impartial system of laws, based principally on the “artifice” of contract (Contractarianism). He supported freedom of the press; he was sympathetic to elected representationand democracy (when suitably constrained); he believed that private property was not a natural right (as John Locke held), but that it was justified because resources are limited; he was optimistic about social progress arising from the economic development that comes with the expansion of trade; and he counselled strongly against revolution and resistance to governments except in cases of the most egregious tyranny.

Although best known today as a philosopher, Hume also developed many of the ideas that are still prevalent in the field of economics, and Adam Smith, among others, acknowledged Hume’s influence on his own economics and Political Philosophy. Hume believed in the need for an unequal distribution of property, on the grounds that perfect equality would destroy the ideas of thrift and industry, and thus ultimately lead to impoverishment. He was among the first to develop the concept of automatic price-specie flow, and proposed a theory of beneficial inflation, which was later to be developed by John Maynard Keynes (1883 – 1946).

Hume was also famous as a prose stylist, and pioneered the essay as a literary genre, publicly engaging with contemporary intellectual luminaries such as Jean-Jacques Rousseau, Adam Smith, James Boswell (1740 – 1795), Joseph Butler(1692 – 1752) and Thomas Reid (1710 – 1796).

But it was as a historian that Hume finally achieved literary fame. His immense 6-volume “History of England” (subtitled “From the Invasion of Julius Caesar to the Revolution in 1688”), written between 1745 and 1760, is a work of immense sweep, running to over a million words. It became a best-seller in its day and became the standard work on English history for many years.


Voltaire (1694 – 1778)


voltaireVoltaire (real name François-Marie Arouet) (1694 – 1778) was a French philosopher and writer of the Age of Enlightenment. His intelligence, wit and style made him one of France’s greatest writers and philosophers, despite the controversy he attracted.

He was an outspoken supporter of social reform(including the defence of civil liberties, freedom of religion and free trade), despite the strict censorship laws and harsh penalties of the period, and made use of his satirical works to criticize Catholic dogma and the French institutions of his day. Along with John LockeThomas Hobbes and Jean-Jacques Rousseau, his works and ideas influenced important thinkers of both the American and French Revolutions.

He was a prolific writer, and produced works in almost every literary form (plays, poetry, novels, essays, historical and scientific works, over 21,000 letters and over two thousand books and pamphlets).


Voltaire was born on 21 November 1694 in Paris, France, the youngest of five children in a middle-class family. His father was François Arouet, a notary and minor treasury official; his mother was Marie Marguerite d’Aumart, from a noble family of Poitou province.

Voltaire was educated by Jesuits at the Collège Louis-le-Grand in Paris from 1704 to 1711, where he showed an early gift for languages, learning Latin and Greek as a child, and later becoming fluent in Italian, Spanish and English as well. He, however, claimed that he learned nothing but “Latin and the Stupidities”.

By the time he left college, Voltaire had already decided he wanted to become a writer. However, his father very much wanted him to become a lawyer, so Voltaire pretended to work in Paris as an assistant to a lawyer, while actually spending much of his time writing satirical poetry. Even when his father found him out and sent him to study law in the provinces, he nevertheless continued to write.

Voltaire’s wit soon made him popular among some of the aristocratic families of Paris and he became a favourite in society circles. When Voltaire’s father obtained a job for him as a secretary to the French ambassador in the Netherlands, Voltaire fell in love with a French refugee named Catherine Olympe Dunoyer, but their scandalous elopement was foiled by Voltaire’s father and he was forced to return to France.

From an early age, Voltaire had trouble with the French authorities for his energetic attacks on the government and the Catholic Church, which resulted in numerous imprisonments and exiles throughout his life. In 1717, still in his early twenties, he became involved in the Cellamare conspiracy of Giulio Alberoni against Philippe II, Duke of Orléans (then Regent for King Louis XV of France), and his writings about the Regent led to him being imprisoned in the infamous Bastille for eleven months. While there, however, he wrote his debut play, “Oedipe”, whose success established his reputation. In 1718, following this incarceration, he adopted the name “Voltaire” (a complex anagrammatical play on words), both as a pen-name and for daily use, which many have seen as marking his formal separation from his family and his past.

When he offended a young nobleman, the Chevalier de Rohan, in 1726 a lettre de cachet was issued to exile Voltaire without a trial and he spent almost three years in England from 1726 to 1729. The experience greatly influenced his ideas and experiences, and he was particularly impressed by Britain’s constitutional monarchy, its support of the freedoms of speech and religion, as well as the philosophy of John Locke and the scientific works of Sir Isaac Newton (1642 – 1726) on optics and gravity. After he returned to Paris, he published his views on British government, literature and religion in a collection entitled “Lettres philosophiques sur les Anglais” (“Philosophical letters on the English”), which met great controversy in France (including the burning of copies of the work), and Voltaire was again forced to leave Paris in 1734.

His second exile, from 1734 until 1749, was spent at the Château de Cirey (near Luneville in northeastern France). The Château was owned by the Marquis Florent-Claude du Châtelet and his wife, the intellectual Marquise Émilie du Châtelet (1706 – 1749), although Voltaire put some of his own money into the building’s renovation. He began a fifteen year relationship with the Marquise, both as lovers and as collaborators in their intellectual pursuits, during which they collected and studied over 21,000 books and performed experiments in the natural sciences in a laboratory. He continued to write, often in collaboration with the Marquise, both fiction and scientific and historical treatises, as well as on more philosophical subjects (especially Metaphysics, the justification for the existence of God and the validity of the Bible). He renounced religion, and called for the separation of church and state and for more religious freedom. Nevertheless, he was voted into the Academie Francaise in 1746.

After the death of the Marquise in 1749 (and continuing disputes over his work “Zadig” of 1747), Voltaire moved to Potsdam (near Berlin) to join Frederick the Great (1712 – 1786), a great friend and admirer of his, with a salary of 20,000 francs a year. After a promising start, Voltaire attracted more controversy in 1753 with his attack on the president of the Berlin Academy of Science, which greatly angered Frederick. Once again, documents were burned and he fled toward Paris to avoid arrest, but Louis XV had banned him from returning to Paris, so instead he turned to Geneva, Switzerland, where he bought a large estate. Although he was welcomed at first, the law in Geneva banned theatrical performances and the publication of his works and Voltaire eventually left the city in despair.

In 1759, he finally settled at an estate called Ferney, close to the Swiss border, where he lived most of his last 20 years until just before of his death, and where he continued to receive all the intellectual elite of his time. His frustrating experiences of recent years inspired his best-known work, “Candide, ou l’Optimisme” (“Candide, or Optimism”) of 1759, a satire on the philosophy of Gottfried Leibniz and on religious and philosophical optimism in general.

Voltaire returned to a hero’s welcome in Paris in 1778, at the age of 83. However, the excitement of the trip was too much for him and he died on 30 May 1778 in Paris. His last words are said to have been, “For God’s sake, let me die in peace”. Because of his criticism of the church, he was denied burial in church ground, although he was finally buried at an abbey in Champagne and, in 1791, his remains were moved to a resting place in the Panthéon in Paris. His heart was removed from his body and now lies in the Bibliotheque Nationale in Paris, and his brain was also removed (although, after a series of passings-on over 100 years, it apparently disappeared after an auction).


Voltaire was a prolific writer, and produced works in almost every literary form(plays, poetry, novels, essays, historical and scientific works, over 21,000 letters and over two thousand books and pamphlets). Many of his prose works and romances were written as polemics, and were often preceded by his caustic yet conversational prefaces. “Candide” (1759), one of the best known and most successful, for example, attacked the philosophy of Gottfried Leibniz and his religious and philosophical optimism in a masterpiece of satire and irony. However, Voltaire also rejected Blaise Pascal‘s pessimistic philosophy of man’s depravity, and tried to steer a middle course in which man was able to find moral virtue through reason.

Voltaire’s largest philosophical work was the “Dictionnaire philosophique”(“Philosophical Dictionary”), published in 1764 and comprising articles contributed by him to the “Encyclopédie, ou dictionnaire raisonné des sciences, des arts et des métiers” (“Encyclopedia, or a systematic dictionary of the sciences, arts and crafts”) (1751 – 1772) and several minor pieces. It directed criticisms at French political institutions, Voltaire’s personal enemies, the Bible and the Roman Catholic Church.

He is remembered and honoured in France as a courageous polemicist who indefatigably fought for civil rights (the right to a fair trial, freedom of speechand freedom of religion) and who denounced the hypocrisies and injustices of the Ancien Régime, which involved an unfair balance of power and taxes between the First Estate (the clergy), the Second Estate (the nobles), and the Third Estate(the commoners and middle class, who were burdened with most of the taxes). Voltaire saw the French bourgeoisie as too small and ineffective, the aristocracy as parasitic and corrupt, the commoners as ignorant and superstitious, and the church as a static force useful only to provide backing for revolutionaries.

Although he argued on intellectual grounds for the establishment of a constitutional monarchy in France, suggesting a bias towards Liberalism, he actually distrusted democracy, which he saw as propagating the idiocy of the masses. He saw an enlightened monarch or absolutist (a benevolent despotism, similar to that advocated by Plato), advised by philosophers like himself, as the only way to bring about necessary change, arguing that it was in the monarch’s rational interest to improve the power and wealth of his subjects and kingdom.

Voltaire is often thought of as an atheist, although he did in fact take part in religious activities and even built a chapel at his estate at Ferney. The chief source for the misconception is a line from one of his poems (called “Epistle to the author of the book, The Three Impostors”) which is usually translated as: “If God did not exist, it would be necessary to invent Him”. Many commentators have argued that this is an ironical way of saying that that it does not matter whether God exists or not, although others claim that it is clear from the rest of the poem that any criticism was more focused towards the actions of organized religion, rather than towards the concept of religion itself.

In fact, like many other key figures during the European Enlightenment, Voltaire considered himself a Deist, and he was instrumental in Deism’s spread from England to France during his lifetime. He did not believe that absolute faith, based upon any particular or singular religious text or tradition of revelation, was needed to believe in God. He wrote, “It is perfectly evident to my mind that there exists a necessary, eternal, supreme, and intelligent being. This is no matter of faith, but of reason”. Indeed, his focus on the idea of a universe based on reason and a respect for nature reflected the Pantheism which was increasingly popular throughout the 17th and 18th Centuries.

While not an atheist as such, he was however, opposed to organized religion. Certainly, he was highly critical of the prevailing Catholicism, and in particular he believed that the Bible was an outdated legal and/or moral reference, that it was largely metaphorical anyway (although it still taught some good lessons), and that it was a work of Man and not a divine gift, all of which gained him somewhat of a bad reputation in the Catholic Church. His attitude towards Islam varied from “a false and barbarous sect” to “a wise, severe, chaste, and humane religion”. He also showed at one point an inclination towards the ideas of Hinduism and the works of Brahmin priests.

Voltaire is known for many memorable aphorisms, although they are often quoted out of context. “If God did not exist, it would be necessary to invent Him”, as has been mentioned, is still hotly debated as to its meaning and intentions. “All is for the best in the best of all possible worlds”, from his novella “Candide”, is actually a parody of the optimism of Leibniz and religion. The most often cited quotation of Voltaire is actually totally apocryphal: “I disapprove of what you say, but I will defend to the death your right to say it” was actually written by Evelyn Beatrice Hall in her 1906 biography of Voltaire and others, although it does capture the spirit of Voltaire’s attitude.

Bishop George Berkeley (1685 – 1753)


berkeleyBishop George Berkeley (1685 – 1753) was an Irish philosopher of the Age of Enlightenment, best known for his theory of Immaterialism, a type of Idealism (he is sometimes considered the father of modern Idealism). Along with John Locke and David Hume, he is also a major figure in the British Empiricism movement, although his Empiricism is of a much more radical kind, arising from his mantra “to be is to be perceived”.

He was a brilliant critic of his predecessors, particularly DescartesMalebrancheLocke and Hobbes, and a talented metaphysician capable of defending the apparently counter-intuitive theory of Immaterialism. He also had some minor influence on the development of mathematics (and calculus in particular).


George Berkeley (pronounced BARK-lee) was born on 12 March 1685 at his family home, Dysart Castle, in County Kilkenny, southern Ireland. He was the eldest son of William Berkeley, a member of the junior branch of the noble English family of Berkeley. He was educated at local Kilkenny College and then, in 1700, at Trinity College, Dublin, where he completed his undergraduate degree in 1704, went on to became a Junior Fellow in 1707. He was ordained in the Anglican Church in 1710, but he remained associated with Trinity College until 1724 (after completing his doctorate, he became a Senior Fellow in 1717, and then became a tutor and lecturer in Greek), although he was not continuously in residence.

His most widely-read works (“A Treatise Concerning the Principles of Human Knowledge” of 1710, and “Three Dialogues between Hylas and Philonous”of 1713) were published at a relatively early age, during his Trinity College years, and he spent much of the rest of his life defending them. In 1713, he went to London to arrange publication of the second of these, and there he befriended some of the intellectual lights of the time, including Jonathan Swift (1667 – 1745), Joseph Addison (1672 – 1719), Richard Steele (1672 – 1729) and Alexander Pope (1688 – 1744). From 1714 to 1720, he interspersed his academic endeavours with periods of extensive travel throughout Europe.

In 1721, he took Holy Orders in the Church of Ireland, earned his doctorate in Divinity, and once again chose to remain at Trinity College, Dublin, lecturing on Divinity and Hebrew. In 1724, he was made Dean of Derry and moved away from Trinity, but in 1725 he gave up this position to pursue plans to found a seminary for training missionaries in Bermuda. In 1728, he married Anne Forster, daughter of the Lord Chief Justice of Ireland, and together they moved to Rhode Island in America and bought Whitehall Plantation, where he wrote the bulk of “Alciphron” (his defence of Christianity against free-thinking). But, when the money for his proposed missionary college did not materialize, he moved back to London in 1732, where he was one of the original governors of the Foundling Hospital, a home for the city’s abandoned children.

In 1734, he was appointed Bishop of Cloyne in Ireland, an economically poor Anglican diocese in a predominantly Roman Catholic country, where he remained for the next 18 years (and during which time he produced a work on mathematicsand calculus, and two popular books on the medical benefits of pine tar). In 1752, he retired to Oxford to live with his son, George, (one of his seven children, although only three lived to adulthood). However, but he died soon afterwards (on 14 January 1753) and was buried in Christ Church Cathedral, Oxford.


Berkeley’s earliest published works were on mathematics and on optics (the latter, dealing with matters of visual distance, magnitude, position and problems of sight and touch, was controversial at the time, but became an established part of the theory of optics). But all the philosophical works for which he has become famous were also written while he was still a young man in in his 20s.

In 1710, still only 25 years old, his “Treatise concerning the Principles of Human Knowledge” was published, his first exposition of the then revolutionary theory that objects exist only as perception and not as matter separate from perception, summed up in his dictum “Esse est percipi” (“To be is to be perceived”). The work is beautifully written and dense with cogent arguments, no matter how counter-intuitive the system may appear at first sight .

He called the theory Immaterialism (conceived as it was in opposition to the prevailing Materialism of the time), although it was later referred to by others as Subjective Idealism. The theory propounds the view that reality consists exclusively of minds and their ideas, and that individuals can only directly know sensations and ideas, not the objects themselves. The position that the mind is the only thing that can be known to exist (and that knowledge of anything outside the mind is unjustified) is known as Solipsism, and forms the root of the later doctrine of Phenomenalism. It can also be seen as an extreme type of Empiricism, whereby any knowledge of the empirical world is to be obtained only through direct perception.

Berkeley, recognizing the possible theological loopholes in his theory, argued that if he or another person saw a table, for example, then that table existed; however, if no one saw the table, then it could only continue to exist if it was in an infinite mindthat perceives all, i.e. God. He further argued that it is God who causes us to experience physical objects by directly willing us to experience matter (thus avoiding the extra, unnecessary step of creating that matter).

So, Berkeley’s view of reality might be summed up as follows: there exists an infinite spirit (God) and a multitude of finite spirits (humans), and we are in communication with God via our experience. Thus, what we take to be our whole experience of the world is analogous to God’s language, God’s way of talking to us, and all the laws of science and Nature we see around us are analogous to the grammar of God’s language. There is, then, in this theory, no need to postulate the existence of matter at all, as all reality is effectively mental.

Although usually counted among the British Empiricists, Berkeley’s Empiricism is of a much more radical and tenuous kind than that of Locke or Hume. Berkeley believed that, for an idea to exist, and for someone to be aware of it, were essentially the same thing (“to be is to be perceived”), and that it was only through experience that we can know about these ideas. A Rationalist would suggest that it is our intellect that enables us to penetrate beyond these surface experiences, and to grasp the underlying substance to which all the various qualities adhere. Berkeley, however, declared unequivocally “Pure Intellect I understand not”, and maintained that the sensible qualities of bodies and things are all that we can know of them. In that respect, then, he was an Empiricist, although he differed from Locke or Hume in believing that what we were “experiencing” were only ideas (or perceptions or qualities) sent from God and not the things themselves, and he effectively chose to make knowledge of self and knowledge of God specific exceptions from the Empiricist mantra that experience is the source of all knowledge.

Although Berkeley insisted that his theory was not skeptical in nature, and that he was not actually denying the existence of anything, it was largely received with ridicule at the time, and even those few who recognized the genius of the arguments were unconvinced by them (Dr. Samuel Johnson is reputed to have kicked a heavy stone and exclaimed, “I refute it thus!”). His “Three Dialogues between Hylas and Philonous” of 1713 was published as a defence against the criticisms his first work received. In it, the characters Philonous and Hylas represent Berkeley himself and his contemporary .

In 1734, Berkeley published “The Analyst”, a direct attack on the logical foundations and principles of calculus and, in particular, the notion of fluxion or infinitesimal change which Sir Isaac Newton (1643 – 1727) and Gottfried Leibniz had used to develop calculus. Berkeley saw this as part of his broader campaign against the religious implications of Newtonian mechanics and against Deism. It was arguably as a result of this controversy that the foundations of calculus were rewritten in a much more formal and rigorous form, using the concept of limits.

Interestingly, and perhaps ironically, the 20th century philosopher Karl Popper(1902 – 1994) published a paper in 1953 called “A Note on Berkeley as a Presursor to Mach and Einstein” in which he described 21 theses from Berkeley’s work and showed how they mirrored concepts in modern physics.

In political economy, Berkeley was a thorough pessimist, perhaps explained by the miserable economic state of the Ireland of his time. He argued for government and Church intervention in creating the social climate for economic development in Ireland, and the doctrine of John Law (1671 – 1729) that “easy money is the engine of trade” was central to his policy arguments. His economics are perhaps best found in his “Querist” of 1737.