If this is so, then Hume is an exception. Although Hume did produce works that are arguably better, such as his Dialogues Concerning Natural Religion (written 1751, published posthumously), which to this day remains probably the best and easily the most influential book in natural theology (i.e., theology not based on revelation or scripture) ever written, it is the Treatise that is rightly regarded, by others if not by himself, as Hume’s magnum opus. The first two books of the Treatise were published anonymously in 1739 when Hume was twenty-eight, and the final book appeared a year later.

The three books of the Treatise can be read separately, though books one and two are best read together. An understanding of the terminology of impressions and ideas articulated in book one is also necessary, as Hume cautions, for book three. In the Treatise, Hume says, “The subjects of the understanding and passions make a compleat chain of reasoning by themselves; and I was willing to take advantage of this natural division, in order to try the taste of the public. If I have the good fortune to meet with success, I shall proceed to the examination of morals, politics, and criticism; which will compleat this Treatise of human nature.”

It is difficult not to ponder what led Hume to France and what formed the personally problematic background against which the Treatise was written. Hume’s underlying emotional motivations and the nature of the problems that led him to seek medical help at the time he started writing the Treatise lead the reader to question the relevancy of its autobiographical elements. Surely it must have been love or another emotion rather than intellect that impassioned Hume to write the Treatise. It is, after all, Hume himself who argues that action is motivated by emotion and passion rather than reason: “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.” At any rate, one will look in vain in the Treatise for clues to any motivating disturbance in Hume’s life, just as one will find it difficult to see much direct influence that the Treatise may have had on his six-volume History of England (published 1754-1761), or on some of his other writings, philosophical and otherwise, that met with greater success during his lifetime.

 

The Treatise can be contextualized, philosophically speaking, by being read against the background of the great British Empiricists, Locke and Berkeley, and others such as Nicolas Malebranche, Pierre Bayle, and Francis Hutcheson, who preceded and influenced Hume. The literature on who did or did not, or may or may not have, influenced Hume is, as one would expect, considerable. The empirical cornerstone of the Treatise—the supposition that with a few classes of exceptions, ideas are copies of sensory impressions, is found in Locke’s Essay Concerning Human Understanding, “while many of Hume’s arguments concerning the nature of objects and abstract ideas are taken almost directly from Berkeley.” Eric Steinberg says:

Unlike both [Locke and Berkeley], Hume broke completely from the orthodox philosophical assumptions then in vogue. Hume’s departure is not a matter of degree, a matter of having gone further than his two predecessors on the continuum from the often-dogmatic rationalism of the seventeenth century to the more open-minded empiricism of the eighteenth century. Instead, it is a major break with some of the underpinnings of all these systems, Locke’s and Berkeley’s included—most notably, their appeal to God and the acceptance of venerable and well-entrenched philosophical distinctions. Hume recognized this when he wrote to Henry Home in 1739, “My principles . . . would produce almost a total alteration in philosophy: and you know, revolutions of this kind are not easily brought about.”6

In the first instance however, the Treatise should be read in contrast to those Hume sees as his principal adversaries. These are the non-empirical “dogmatic rationalists,” with the “sophistry and illusion” found in their “divinity and school metaphysics.” To read it in this latter way one need only read the Treatise itself, since Hume discusses those positions he wishes to refute.

Hume’s theory concerning impressions and ideas is crucial to just about every central argument in the Treatise, and it is arguably here, in the very first pages of the book, that basic difficulties with Hume’s arguments about, for example, causation, personal identity, reasoning based on experience (a posteriori reasoning), scepticism and the external world, inductive reasoning, and even the foundations of ethics and nature of morality are to be traced—as they were, for example, by Thomas Reid. Hume carefully and ingeniously traces out the implications of his theory of impressions and ideas in the Treatise—this is what the Treatise is. He contends that some of our most common and central beliefs about things like God are held dogmatically rather than on the basis of reason or valid rational inference. Beliefs in causal connections and in personal identity are different, however. They are not a matter of dogmatism, but of human nature; they are the philosophical fictions we cannot help but form and whose origins Hume analyzes in some depth. But the idea of God is not among these fictions. This is why Hume saw the Treatise as so “revolutionary.” Commonly held beliefs about these matters cannot be found to be rationally grounded in experience because we have no sense “impressions” and hence no corresponding “ideas” or concepts for the entities or relations to which they allegedly refer. Belief in an independent external world, as well as in objective causal necessity, and even in a continuing personal self, is based on imagination. They are fictions of the imagination that are fostered by an association of ideas and by resemblance, contiguity in space and/or time, and constant conjunction. It is these “natural” relations that underlie the way we happen to naturally judge things. We believe in causal necessity, and those other things, not on the basis of reason and argument, but due to what Hume terms “custom.” They are the result of feelings and imagination that naturally occur and provide us with the illusion of something not actually experienced.

One of the most attractive things about Hume in relation to his own work is the conundrums he sometimes finds himself in when following a line of reasoning to its logical conclusion. These are sometimes conclusions that he sees himself as compelled to accept, but cannot accept because they are so antithetical to the natural way one is inclined to think and believe as a matter of course. Among the best known of these are his views about personal identity.