Part 4/9:
Impressions vs. Ideas: A Philosophical Dichotomy
In Hume's framework, all perceptions are made up of these two types of experiences. For instance, looking at an apple provides an immediate impression, while recalling it later provides an idea. Hume argues there can be no idea without a corresponding impression, leading to the idea that our knowledge is derived from experience.
This leads to a prominent challenge within Hume's system, which is exemplified when considering the concept of a missing shade of blue. If someone had never experienced blue before but saw a gradient missing a particular shade, could they conceive of it? Hume believed affirmatively that they could not, as it clashes with his theory that simple ideas stem from prior impressions.