David Hume, a Scottish philosopher and historian, thrived during the Enlightenment era. In this segment of history, which is also known as the Age of Reason, European scholars attempted to find the root of knowledge, often by working through one of two prevalent schools of thought, empiricism and rationalism. Hume, an empiricist, suggested that knowledge is gained from sensory experiences. Yet Rene Descartes, a French rationalist, advanced the thought that knowledge is based on reason and intellect. These two ideologies differ foundationally, and Hume’s arguments promoting empiricism in his work An Enquiry Concerning Human Understanding justify his suggestion that we should disregard Descartes’ work. While it should not be assumed that Hume wished to literally “commit [Descartes’ work] then to the flames,” Hume made clear that he did not see truth in Descartes’ method of epistemology. In addition to the pointing out the logical fallacies that Descartes’ work possesses, Hume’s critique is premised on his methodology of proving certainty, sense of self, and existence of God.
In his work Discourse on Method, Rene Descartes suggested that one should utilize methodological doubt to question the surrounding world. On page 11, he said, “the first [step] was never to accept anything as true that I did not plainly know to be such; that is to say, carefully to avoid hasty judgement and prejudice; and to include nothing more in my judgements than what was presented to itself to my mind so clearly and so distinctly that I had no occasion to call it in doubt.” Hume, too, acknowledged that a foundation of basic truths such as principles of mathematics is a key step towards solidifying knowledge. In the Enquiry, Hume argued, “to begin with clear and self-evident principles, to advance by timorous and sure steps, to review frequently our conclusions, and examine accurately all their consequences; though by these means we shall make both a slow and a short progress in our systems; are the only methods, by which we can ever hope to reach truth, and attain a proper stability and certainty in our determinations” (pg. 103). Where he disagrees, however, is in the radicalness of doubt that Descartes utilized. Hume wrote that there is no “original principle, which has a prerogative above others, that are self-evident and convincing: or if there were, could we advance a step beyond it, but by the use of those very faculties, of which we are supposed to be already different.” He also claimed that “the CARTESIAN doubt, therefore, were it ever possible to be attained by any human creature (as it plainly is not) would be entirely incurable; and no reasoning could ever bring us to a state of assurance and conviction upon any subject” (pg. 103). These statements suggest that Hume believes in a more moderate form of skepticism, and believes that Cartesian methods are of no benefit.
In regard to one’s sense of self, Descartes argued for the concept of the “cogito,” which posits that if he could think and subsequently doubt, then he certainly existed. This concept led him to the statement “I think, therefore I am,” which in and of itself completely contradicts his method of arriving at knowledge: doubting everything, including the term “I” and the sense of self (pg.18). Hume believed that Descartes’ method was of no use. On page 5 of the Enquiry, Hume contended that metaphysics was an “abstract philosophy” that is “objected to, not only as painful and fatiguing, but as the inevitable source of uncertainty and error.” On the same page, he claimed that that metaphysics was not even a true science and that it arose from either “the fruitless efforts of human vanity, which would penetrate into subjects utterly inaccessible to the understanding, or from the craft of popular superstitions, which, being unable to defend themselves on fair ground, raise these entangling brambles to cover and protect their weakness.” This refutation of Descartes’ sense of self stems from Hume’s belief that genuine knowledge is gained empirically, from experience. For Hume, Descartes’ philosophical reasoning is not adequate evidence to prove a true self awareness.
On the topic of an omnipotent figure, Descartes stated in the Discourse, “since I knew of some perfections that I did not at all possess,” that “there must be something else more perfect, upon which I depended, and from which I had acquired all that I had” (pg. 19-20). This logic that reason itself can justify the existence of a God runs counter to the argument of empiricism. Tied into Hume’s general disapproval of metaphysics is this denial of a God-like figure. For Hume, there was a firm demarcation between impressions and ideas. Impressions, based on first-hand experience, are vivid and lively. Ideas, on the other hand, are copies of impressions that can be developed through resemblance, contiguity, or cause and effect. In the Enquiry, Hume wrote that if it is true that a God exists and can, for example, cause light to appear by giving a simple command, “it requires as certain experiences, as that of which we are possessed, to convince us, that such extraordinary effects do ever result from a simple act of volition” (pg. 45-46). Thus, Hume’s statements in the Enquiry serve as stark evidence that he denounced Descartes’ concept of a God.
Though Hume and Descartes shared a similar view of creating an initial foundation of basic truths on which one should build knowledge, it is clear from An Enquiry Concerning Human Understanding that Hume wished that all would disregard Descartes’ school of thought. Hume believed that the most desirable way to gain knowledge was to utilize a more moderate form of Descartes’ skepticism. To Hume, certainty resided in the senses and, to Descartes, certainty resided in the mind. Overall, the statements opposing Descartes in the Enquiry outweigh the statements that support his methodology.