Hume: Ideas are imitations of sense perceptions

David Hume believed that the most direct, "lively" mental images are those caused by sensory impressions, and that the gyrations of the imagination and intellect are weak imitations or hybrids. "All the colours of poetry, however splendid," he wrote, "can never paint natural objects in such a manner as to make the description be taken for a real landscape. The most lively thought is still inferior to the dullest sensation." I am unsure whether I agree with this, particular as, during my morning meditation, my opinions on Hume's book nearly succeeded in crowding out my attention to a bird chirping outside my window. He also applied this to emotion, pointing out that we can recognize or imagine emotion in ourselves and others without actually feeling that emotion: "A man in a fit of anger, is actuated in a very different manner from one who only thinks of that emotion. If you tell me, that any person is in love, I easily understand your meaning, and form a just conception of his situation; but never can mistake that conception for the real disorders and agitations of the passion." One might add--I wish to point out--that when we hear of others' fortunes and misfortunes we often have our own emotional responses. Thus, when we hear about someone's unjust punishment, we actually become angry on her behalf, and when we watch the hero kiss his beloved on a movie screen, we actually feel the love we imagine he feels. Many of our mental creations are hybrids in the simplest and most literal sense. "What never was seen, or heard of, may yet be conceived...When we think of a golden mountain, we only join two consistent ideas, gold, and mountain..." And yet, these ideas ultimately must be rooted in experience. He wrote, "A blind man can form no notion of colours, a deaf man of sounds." He also applied this to virtue: "A man of mild manners can form no idea of inveterate revenge or cruelty, nor can a selfish heart easily conceive the heights of friendship and generosity." Though it feels depressing to say so, this seems true to some degree. Why is it that deeply felt impulses and ethical commitments are so difficult to sympathize with in other people who experience them differently? If we were capable of understanding each other better, surely this would promote peace.

Source: David Hume. Enquiry Concerning Human Understanding. (1772) Section II: Of the Origin of Ideas.

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Bonus: An adaptation of a short paper I wrote for college c. 2000. Revised 2022.

Hume's Enquirey into Knowledge of Matters of Fact

Hume, in Section IV of his Enquiry Concerning Human Understanding, divides the objects of knowledge into two kinds: relations of ideas (whose truth we can prove) and matters of fact (which could always be different). So, how can we be certain about facts? Hume claimed that philosophers had yet explored it to his satisfaction.

First: We know some facts by immediate sense perception or by memory. Others, we know because we assume that an effect has an appropriate cause. A friend sends us a letter about a trip to France; this suggests to us that the friend is in France. The cause-and-effect relationship isn't known a priori but rather from experience.

Next: When we draw conclusions from experience, they aren't purely rational. We simply can't reason that the future will be exactly like the past. We've eaten bread in the past, but what is this breadlike meal before us now? Is it also bread? Will it nourish us? Hume questions the rationalist tradition that knowledge gained from experience is ultimately founded on reason.

In Section V, Hume offers a "sceptical solution" to his doubts. We have "natural instincts" to draw conclusions. It's custom or habit. Our reason is powerless to alter our conclusion. We see one action followed by another. The pattern repeats. We begin to believe it is cause and effect, though we have no rational explanation. And our experience does become "useful to us" when we draw the conclusion.

Logic is limited, he observes. Logic manipulates "relations of ideas" but not "matters of fact." That's why the scientific method involves experimental testing of a hypothesis. Scientists don't always work out their answer with pencil and paper alone, not only because it's hard, slow work to do it that way, but because it might not even be possible to do it that way. Repeated observations may be a better method. With the assurance attained through observation, our beliefs become pragmatically useful to us. We acquire knowledge. This is applicable not only to scientific ventures but to all of human life.

Hume acknowledges our beliefs are never certain.

Neither should we. After all, theories are only hypotheses that have been confirmed multiple times, and "natural laws" are only theories that have stood the test of time. If a contradictory event is ever observed, the theory or natural law will shatter. We can never prove matter of fact beyond doubt. Theories and beliefs are subject to factual observation. We are only certain of our beliefs insofar as they have not yet been proven wrong and our certainty remains useful to us.

Hume is aware that, starting with our observations, we must make an irrational, explicable leap to gain knowledge of cause and effect. After all, we could not function in the world without knowing anything about cause and effect. Though we gain this knowledge from custom and habit rather than from reason, we have no choice, he says, but to trust it.

Hume recognizes that some components of human knowledge are so fundamental that we cannot investigate them. At some point, we can no longer reason about our reasoning process or observe our process of observation. Hume's skepticism about the foundation of knowledge manifests intellectual humility. His conclusion that we gain knowledge through "custom or habit" is satisfactory for a non-scientific approach to human understanding.

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