An Enquiry Concerning Human Understanding

David Hume·1777

Hume's recasting of the first book of his Treatise: where our ideas come from, why our expectations from experience rest on custom rather than reason, what necessary connexion and liberty amount to, why testimony can never establish a miracle, and what a mitigated scepticism leaves us with.

Contents

1. Section I. Of the different Species of Philosophy

   Moral philosophy can be easy and obvious, painting virtue to move us to act, or accurate and abstruse, seeking the principles of human nature. Hume defends the second: it lends exactness to the first and to every art, and only a careful study of the understanding can drive out the false metaphysics that shelters superstition.

2. Section II. Of the Origin of Ideas

   All the contents of the mind are either impressions, the lively perceptions of sense and feeling, or ideas, their fainter copies. Every idea is copied from some impression, so the way to test a philosophical term is to ask from what impression its idea is derived.

3. Section III. Of the Association of Ideas

   Ideas are joined in the mind by only three principles of connexion: resemblance, contiguity in time or place, and cause or effect.

4. Section IV. Sceptical Doubts concerning the Operations of the Understanding

   Reasonings about matters of fact rest on cause and effect, and our knowledge of causes comes wholly from experience, not reason. But no argument shows that the future will resemble the past, so our conclusions from experience are not founded on reasoning at all.

5. Section V. Sceptical Solution of these Doubts

   What leads us from past experience to expect the like in future is custom, or habit, the great guide of human life. Belief is a more vivid and steady conception of an idea, produced by custom, and the mind's connexions of ideas work in the same way.

6. Section VI. Of Probability

   Where chances or causes are mixed, the mind leans towards the side with more instances, and the strength of our expectation follows the proportion of past experience.

7. Section VII. Of the Idea of necessary Connexion

   We never perceive any power or necessary connexion between causes and effects, in bodies or in our own wills. The idea arises from the feeling of the mind's customary transition from one event to its usual attendant, and Hume offers two definitions of cause.

8. Section VIII. Of Liberty and Necessity

   The dispute between liberty and necessity is merely verbal. All men have always believed in the regularity of human actions, which is all necessity amounts to, and liberty, properly understood as acting according to our will, is consistent with it and required by morality.

9. Section IX. Of the Reason of Animals

   Animals, like us, learn from experience and infer effects from causes. Since they plainly do it without reasoning, by custom, this confirms that our own inferences from experience rest on custom too.

10. Section X. Of Miracles

    A wise man proportions his belief to the evidence. A miracle is a violation of the laws of nature, against which experience is as complete as it can be, so no testimony can establish one unless its falsehood would be more miraculous than the fact it relates; and no actual testimony has ever met that standard.

11. Section XI. Of a particular Providence and of a future State

    In a dialogue with a friend who speaks for Epicurus, Hume argues that from the order of the world we can infer a cause only as great as the effect shows, and never a providence or a future state of rewards and punishments beyond what we already see.

12. Section XII. Of the academical or sceptical Philosophy

    Hume rejects excessive Pyrrhonian scepticism as unliveable, and recommends a mitigated scepticism that confines enquiry to common life and experience. Books that contain neither abstract reasoning about quantity nor experimental reasoning about fact should be committed to the flames.