Hume, I and many others think, was the greatest philosopher to have written in English, and this is the book to pick up if you want to introduce yourself to Saint David's distinctive brand of classical empiricism. This is a must-read for anyone with even a passing interest in philosophy, and it's hard for me to see how anyone interested in the history of modern thought can avoid reading this book or the corresponding sections of Hume's Treatise.As is well-known, the Enquiry concerning Human Understanding was intended as an encapsulation and popularization of the views Hume defended in Book I of his magnum opus, A Treatise of Human Nature. Hume assumed that book's commercial failure could be accounted for by its length, difficulty, and lack of accessibility, and so, being a man who desired literary fame, he hoped to acquire commercial success by presenting the same ideas in a more appealing and accessible manner. Unfortunately, it seems Hume misunderstood what the literati of his day were looking for in a philosophical treatise. For the Enquiry, like the Treatise before it, didn't bring him the fame he sought. Still, Hume did understand what goes into writing excellent philosophical prose, and consequently this book is a much easier read than Book I of the Treatise. Indeed, this book constitutes an excellent introduction to Hume's thought, and, except for maybe Berkeley's Three Dialogues, I can't think of another primary source that would serve as a better introduction to classical British empiricism.
Now, let's get to the ideas here. Hume, like the other classical empiricists, was primarily concerned with the psychological question of the origin of our concepts. About the answer to this question, the empiricists were all agreed--our concepts are furnished by experience, which includes both sensory experience and introspection (i.e., the experience of our own mental states). And the empiricists also agreed about the way we can justify our beliefs. Some beliefs are true (or false) in virtue of the ideas they contained, and we can know their truth (or falsity) simply by thinking about them; other beliefs are true (or false) in virtue of how the external world is, and we can know their truth (or falsity) only by drawing on our experiences of the world. According to Hume, all substantial conclusions about the world fall into this second category. That is, the truth (or falsity) of all substantial claims about the existence and nature of things in the external world can be discovered only by checking those claims against the evidence of our senses.
The traditional way of placing Hume within the story of empiricism goes something like this. Hume takes up the empiricism of Locke and Berkeley and pushes it to its logical conclusion. Whereas Locke and Berkeley hadn't been wholly consistent empiricists, Hume, the true believer, demonstrates that classical empiricism leads to a pretty thoroughgoing skepticism. Since he's wholly convinced of the truth of his empiricist premises, Hume is willing to accept the skepticism that goes along with them. However, those who aren't convinced of that his empiricism is obviously correct think that Hume has actually demonstrated the implausibility of his empiricism. If this is where empiricism leads, they think, then it's clear that we need to reject empiricism. Indeed, some, like Thomas Reid, view Hume's arguments as constituting a reductio ad absurdum of his sort of empiricism. On this interpretation, Hume's philosophy essentially presents a dilemma for all future thinkers: abandon empiricism, or accept empiricism along with Humean skepticism.
But a different view of Hume, one of Hume as proposing a wholly naturalistic account of the human mind, has recently emerged as a competitor to the general conception of Hume's place within philosophy sketched in the previous paragraph. This interpretation downplays Hume's skepticism and emphasizes his professed intentions to provide a positive account of the operation of the human mind that appealed to nothing beyond the evidence of our senses. According to proponents of this interpretation, Hume is most interested in a description of the operation of the human mind. He's describing what human nature allows us to know and what it doesn't allow us to know. Furthermore, he argues that our nature is such that, where it fails to provide us with the resources to acquire the knowledge we might want, it provides us with a natural habit of forming the right conclusions anyway. Even though our nature limits our knowledge of the world, it ensures that we possess the habits of mind needed to make our way in the world. Hume dubs all these habits of mind "custom."
If this view is correct, then Hume has abjured many of the normative aims of traditional epistemological inquiry. He isn't attempting to show how we can answer a skeptic or why we have good reason to believe what we think we know. Instead, he wants us to stand back from our everyday beliefs and think about the natural processes that result in them. How, exactly, do our minds operate? How do we come to think what we do about the world? Hume thinks that this sort of inquiry will lead us see that, at some point, the explanation of why we think what we think reaches certain brute facts about the operation of the human mind. When we reach these points, there is nothing more to be said. We simply can't help thinking in these ways, and we lack the resources to demonstrate that these ways of thinking constitute an accurate way to represent the operation of the external world. And, Hume claims, it turns out that many of the fundamental elements of our conception of the world--the belief that things stand in causal relations to one another, the belief that we can know that there is a world outside our minds, the belief the future will resemble the past--end up not being open to ratification by experience. With respect to beliefs of these sorts, we ultimately have to appeal to custom in order to explain their existence and popularity. Hume, then, can be seen as demolishing the pretensions of reason in order to make room for a wholly naturalistic account of human thinking.
