structural:scholar_edition, linguistic:paraphrasing, structural:reformatting, structural:summarization
Impressions and ideas

A central doctrine of Hume's philosophy, stated in the very first lines of the Treatise of Human Nature, is that the mind consists of perceptions, or the mental objects which are present to it, and which divide into two categories: "All the perceptions of the human mind resolve themselves into two distinct kinds, which I shall call impressions and ideas." Hume believed that it would "not be very necessary to employ many words in explaining this distinction", which commentators have generally taken to mean the distinction between feeling and thinking. Controversially, Hume, in some sense, may regard the distinction as a matter of degree, as he takes impressions to be distinguished from ideas on the basis of their force, liveliness, and vivacity — what Henry E. Allison (2008) calls the "FLV criterion." Ideas are therefore "faint" impressions. For example, experiencing the painful sensation of touching a hot pan's handle is more forceful than simply thinking about touching a hot pan. According to Hume, impressions are meant to be the original form of all our ideas. From this, Don Garrett (2002) has coined the term copy principle, referring to Hume's doctrine that all ideas are ultimately copied from some original impression, whether it be a passion or sensation, from which they derive.