Hume held that all that was meaningfully present to the mind consisted in matters of fact (impressions) and relations of ideas. But even ideas were faint impressions themselves, formed over time by associations. Epistemology, dealing with the nature of knowledge, is concerned with the nature of truth and error. For Hume, 'truth' and 'error', if they have meaning, would have to be something traceable to clear and distinct impressions and ideas. Hume himself held that truth consisted in the agreement of an impression or idea and error in the disagreement of an impression or idea. But as such, with impressions and ideas as the starting place of his epistemology, how can the truth about impressions and ideas be properly discussed and founded? Hume's analysis can deal with the notion of truth as it fits into the acceptance of his views about impressions and ideas, but it seems that such an analysis cannot deal with the nature of truth as applied to the question of the justification of such an analysis itself. The question 'what justifies the existence of impressions?' cannot rationally be answered by reference to impressions themselves, and thus, the principle that makes such impressions true must be in some way exterior to the impressions themselves, since it is impressions which are the object under investigation.
Since Hume gave little attention to questions of truth and error, and discussed such matters only in hindsight after assuming epistemological notions about truth and error which he applied to the arguments he provided for his psychological theories, is Hume's skeptic influence on epistemology today not somewhat unfounded? If not, then in what way is Hume redeemed of this oversight?