David Hume: Impressions and Ideas

Guest Contributor: Gerald Brunell

Published on December 12, 2010


In conjunction with our meet-up on August 20th to discuss the philosopher, David Hume, this is the fourth post in a series about his philosophy as it relates to empiricism and skepticism.

There is a distinction between two different perceptions made by David Hume. The first is the root of all ideas called an impression. Impressions as described by Hume are, “all our more lively perceptions, when we hear, or see, or feel, or love, or hate, or desire, or will.”(II 3). Off of these impressions we form our ideas which are, “…less forcible and lively…”(II 3) because all ideas to Hume are just copies of the impression of the first few times we sense something. Ideas must proceed from impressions because, “what never was seen or heard of, may yet be conceived.”(II 4) To do otherwise would be a contradiction to Hume.

[Hume’s] Ideas associate with each other in three ways.

1) Resemblance: This is when, “a picture naturally leads our thoughts to the original.” (III 3) By ‘original’ Hume means the impression of the picture. This is why every time I see a ’96 Black Volkswagen Jetta I think of the one I have and relate.

2) Contiguity of ideas: This is when, “the mention of an idea naturally introduces an inquiry or discourse concerning the others.”(III 3)  This is like the old saying, “I’ve seen them once, I have seen them all” – where our mind associates one idea as being true for all other ideas just like it. If you see one apartment in a building you want to contrast and compare it to the rest of them.

3) Cause and effect:  This is when we, “think of a wound, we can scarcely forbear reflection on the pain which follows it.”(III 3) This type of relation is the idea where we see an effect, and naturally assume the cause of that event. If you walk by a condemned house with burn marks and structural damage you think that a fire must be the cause of the damage.

Like John Locke, Hume believes in the distinction between simple ideas which aggregate into complex ideas.  Because all ideas come from impression, Hume concludes that all simple ideas come from simple impressions. To get the simple idea you abstract from a complex idea many impressions. Fire gives us the complex idea of fire but also the simple impressions of orange, hot, dangerous, burn.

To get to the core of all ideas, Hume implores you to do the simple thing and trace your ideas back to the impressions from which they come. “We shall always find that every idea which we examine is copied from a similar impression.” (II 6).