In “The Origin of Ideas” section Hume begins to lay out what is — as I understand it — the central notion of his philosophy: namely, that reason is beholden to the sentiments. Or, to put it another way, the passions are primary and reason is invoked secondarily. For him, direct perception comes first and memory or imagination are copies — representations — of original perceptions. For example, the fact that I’ve experienced pain after cutting my hand while removing the pit from an avocado has etched itself in my memory, and I take care to prevent it from recurring. However, as he will go on to explain later, this “learning” has nothing to do with reason.
Hume breaks these two types of perceptions into two classes: Impressions and Thoughts/Ideas. By impressions, he means “our more lively perceptions, when we hear, or see, or feel, or love, or hate, or desire, or will” (10). Ideas, on the other hand, are “less lively perceptions, of which we are conscious, when we reflect on any of those sensations or movements above mentioned” (10-11). Hume concludes by asserting that all the “materials of thinking” (Hobbes?) comes from sentiments — be they external and experienced sensually, or internal and experienced psychologically. Any synthesis between the materials occurs in the mind and through the will (I take “will” to both mean conscious thought and unconscious drives, a la Nietzche’s will to power or D&G’s desiring-production, but I’m unsure what exactly Hume means here).
By way of proving this assertion, Hume offers two arguments:
1) All thoughts can be resolved into simple ideas, which are copies of already-experienced feelings or sentiments.
2) If one suffers a physical defect an therefore cannot experience a particular sensation, then that person is not susceptible to the corresponding ideas.
I find these arguments to be both compelling and bit problematic, but I’m going to hold my doubts in abeyance and see where he goes with this. He does offer one anecdote about the possibility of someone imagining a never before-seen shade of blue that is absent from a spectrum of blues, but dismisses it as so singular that it isn’t worth mentioning. This seems a bit odd for an empiricist, but I’ll leave it at that for now.
Closing out Section II, he presents a question that we should always be asking. When confronted with any idea, we should ask “from what impression is that supposed idea derived?” (13).
Section III is barely over a page long, but in it he introduces the three ways in which our minds and wills can combine the materials of thought: though Resemblance, Continguity, and Cause or Effect. He insists that these are the foundational ways by which all mental associations are constructed and asserts — as a good empiricist — that any doubts can be allayed if we “run over several instances, and examine carefully the principle, which binds the different thoughts to each other, never stopping till we render the principle as general as possible” (15).
Postscript: Reading these sections — especially Section II — I make an immediate connection with Lefebvre’s notion of representational space, which he defines as “space as directly lived through its associated images and symbols” (38). It also “embraces the loci of passion, of action, and of lived situations, and thus immediately implies time” (42*). Both the images and passions that Lefebvre references are addressed by Hume’s two classes of perceptions, and I can’t help but wonder if Hume’s insights might enrich Lefebvre’s notion of directly lived space (note that Lefebvre does not mention Hume in The Production of Space; also note that I’m perpetually trying to find ways to make Lefebvre more useful: my most recent attempt was by invoking Marcuse.).
Lastly, here is a recent New York Times op-ed on Hume.
* Reminder that, via Bergson, Deleuze has a keen interest in time and duration.