Critique of Pure Reason

John Locke was a 17th-century British philosopher, physician, and political theorist. His political works include the famed Second Treatise on Government (1688), which presents a social contract theory of influence in the formation of western liberal democracies, like the United States, and the Letter Concerning Toleration (1689) wherein Locke proposes the separation of church and state. Locke was also a rights theorist who claimed that life, liberty, and property are fundamental natural rights.

For Kant, Locke’s most relevant contributions were to empiricist epistemology. Locke is engaged in the Critique of Pure Reason as the central figure of modern empiricism. In his most important work, An Essay Concerning Human Understanding (1689), Locke sought to determine the limits of human knowledge, just as Kant would a century later.

Unlike Kant, Locke’s empiricism includes the view that the human mind is born as a blank slate. All the ideas that the mind comes to identify with itself are originally derived from experience. Kant’s transcendental philosophy is, in part, a response to the deficiencies of such a view. Locke also held a theory of personal identity that was of some import in the development of modern philosophy. This self amounts to the empirical self on the Kantian model, not the transcendental self.

Locke had a long and prestigious medical career. He was also politically active. Strongly opposed to absolute monarchy, he was suspected of involvement in a plot to assassinate the king of England, Charles II. In 1683 he fled to the Netherlands where he lived in exile for five years before returning to England. Locke’s most important works were all published very quickly upon his return. He was 72 at the time of his death in 1704.

In the first half of the 18th century, Wolff produced an enormous amount of philosophical literature in the German language, something previously unachieved. Now he is remembered predominantly as an important link between the rationalism of Gottfried Leibniz and the transcendental idealism of Kant. In 18th-century Germany his systematization of Leibnizian style philosophy was very highly regarded, and Kant thought him “the greatest among all the dogmatic philosophers” (35). His completist, academic attempt at a system of philosophy may have served as an ideal model for Kant.

Wolff was born into a Lutheran family and studied theology, physics, and mathematics at university. He engaged in a long correspondence with Leibniz who was instrumental in supporting Wolff’s career. At the behest of Wolff’s pietist rivals, King Frederick-Wilhelm I exiled Wolff from Prussia in 1723 for his controversial philosophy. In 1740, Wolff returned from exile thanks to the initiative of Frederick the Great, the son of Frederick-Wilhelm I, and a ruler for whom Kant had the utmost respect and admiration. There is no one single of his that is now widely read, though he published on a great variety of philosophical and mathematical topics.

Hume was a controversial Scottish philosopher whose works are of continued importance. At a young age he wrote his masterpiece, A Treatise of Human Nature (1739-1740), the views of which were refined in later works like An Enquiry Concerning Human Understanding (1748). As a librarian, he wrote a massive, six volume History of England (1754-1761) through which he achieved literary fame in his lifetime. Among other things, Hume is remembered for the problem of induction, which states that inductive reasoning always illegitimately goes beyond the observations given in experience when it infers that the future will resemble the past.

For Kant, Hume is the great figure of skepticism. In fact, Kant once wrote that it was Hume’s work that awoke him from his “dogmatic slumber.” This is not to say that Kant ever accepted Hume’s skeptical empiricist approach. Rather, Kant saw that Hume’s skeptical challenge to dogmatic philosophies required a revolutionary answer out of which Kant’s transcendental idealism emerged. Hume believed that morality was based on sentiment, that the self is no more than a bundle of perceptions, and that reason is the servant of passion. His religious opinions bordered on atheism and were radical at the time. Along with Adam Smith and Thomas Reid, Hume is one of the most influential figures of the Scottish Enlightenment. He died in Edinburgh, Scotland, the city of his birth at the age of 65.

Newton is the most esteemed English natural philosopher of the Enlightenment. During his long life, he contributed to an array of different disciplines. Most notable among these include the development of calculus (a credit he shares with Leibniz), and the development of “classical mechanics,” a physical theory of the natural world that has been profoundly influential in the history of physics. His mechanical theory, which includes the still extremely relevant concept of gravity, is most notably elucidated in Mathematical Principles of Natural Philosophy (1687), the book for which he is most widely remembered.

Newton’s philosophy of space is a relevant counter position to Kant’s theory as he articulates it in the transcendental aesthetic. Whereas Kant took space to be an intuition of the mind that structures our perception of the external world, Newton thought space was an absolute magnitude. It exists independently of the mind and of the objects inside of it.

Newton shared a friendship with Locke and many other luminaries and was also involved in heated controversies with Leibniz regarding credit for the invention of calculus. He was a devout Christian whose religion informed his work. When he died in 1724, he was buried in Westminster Abbey.