David Hume Philosopher on The origin of ideas

SECTION II: the Origin of Ideas

11. Everyone agrees that there is a difference between the present perceptions of the mind (as in feeling pain of excessive heat and the pleasure of warmth) and the later memories of these sensations or anticipation of them in his memory. The latter lack the force of the original sentiment. And only a diseased or mad mind cannot know the difference. Even a poet cannot convey the real thing. The most lively thought is always inferior to the dullest sensation.

To be in a fit of anger is different from thinking of that emotion. I can create a conception about another person you say is in love, but my conception is different from his emotion. Our reflections on our past emotions may make copies (as a faithful mirror makes copies), but they will be faint in contrast to the original perceptions.

12. Thus we may divide all perceptions of the mind into two classes: Impressions and Thoughts or ideas. Impressions (and here the meaning is different from the usual) are all our more lively perceptions when we hear, see, feel, love, hate, desire or will. Ideas are all our less lively perceptions when we reflect on these sensations.

13. We may conceive of what we have not seen (monsters and strange shapes) and nothing is beyond our thought except what implies an absolute contradiction [e.g. a square circle]. But all our self-created conceptions (such as a gold mountain or a virtuous horse) are from our faculty of compounding, transposing, augmenting or diminishing materials of thought afforded us by the senses and experiences. All our ideas or more feeble perceptions are copies of our impressions or more lively perceptions.

14-15. I offer two arguments to prove this. First, when we analyse our thoughts we can reduce them to simple ideas that were copied from previous feelings or sentiments. Thus, the idea of the mind of God comes from reflecting on the operations of our own mind and extending, without limit, the qualities of goodness and wisdom. Ask anyone to show an idea that has not been derived from an impression and he cannot offer one. [Our idea of God’s love comes from rationally extending our experience: e.g. our mother’s love.]

The second argument to prove that all our ideas are copies of impressions is this: if a person has a defect in an organ that causes him to lack a sensation, he will also lack the corresponding ideas. A blind man can have no notion of colour or a deaf man of sounds. But restore ability to receive the sensation, and you open the way for the idea. If a Laplander has never applied his taste organ to wine, he will have no idea of it. To a lesser degree, a man of mild manners has no idea of revenge or cruelty; and a man with a selfish heart cannot conceive of good friendship and generosity. In this way others may have ideas of which we have no conception because we have not had the required feelings or sensations.

16. There is, however, one contradictory phenomenon. The sensations of colours which enter the eye and the sensations of sound which enter the ear are distinct from each other. And yet if they are laid out in order, with one shade of colour or sound omitted, one would perceive a blank where the shade or sound is missing. And one should be able to fill in the blank. But this exception should not cause us to question our general maxim: ideas come from sensations.

17. Here is a simple but significant proposition: all ideas (especially abstract ones) are faint and obscure and are apt to be confused with other ideas. But all impressions (that is, all sensations) are strong and difficult to mistake. Therefore if we want to know if a philosophical term has any meaning or idea (and often it does not), all we need to ask is, from what impression is that supposed idea derived. If there is none, then the term has no meaning. To enquire after the impression behind an idea is the way to remove disputes concerning nature and reality.