Two Meanings of the Term "Idea": Acts and Contents in Hume's Treatise

From the Treatise of Human Nature (completed in 1736) to the Appendix (to Book III, published in 1740) and to the Enquiry Concerning Human Understanding (1748) Hume appears to vacillate between two ways of accounting for the formation of belief. The doctrine in the Treatise is explicitly amended in the Appendix and then reversed again in the Enquiry. Hume is at pains to insist, first, that belief is no more than mere conception which is attended by a particular sentiment or feeling (read: impression), rather than by some idea of the existence per se of objects. ¹ Then he corrects himself in the Appendix, saying that conception is "modified" as belief but is not attended by any distinct impression (T 627). In the Abstract of the Treatise published the same year (1740) Hume refers to belief as "a different MANNER of conceiving" (T 653). Later, in the Enquiry, he reverts to his initial formulation: "the difference between fiction and belief lies in some sentiment or feeling, which is annexed to the latter, not the former." ²

This vacillation is a series of attempts to answer the question of how conception, if it is in itself indifferent to its object, can become lively, that is, become a belief in the existence of that object. ³ The fact that Hume appears torn between these two ways of explaining belief and that he was comfortable resting with the attendant model in the later expression of the theory in the Enquiry indicates, I believe, that both models are legitimate descriptions of the genesis of belief, considered from different points of view. ⁴ The attendant model he finds serviceable in the Enquiry is perfectly sound from the vantage of the science of moral human nature: a sensible dimension to belief is central to Hume's position here, a point to which I will return below. ⁵ The question of the different manner of conception is better suited to a discussion of the epistemological notion of belief, because it takes account of differences between acts beyond those differences in the way they feel to the mind. These two versions of the theory of belief, I argue, suggest that there are two distinct meanings for the term "idea": (a) understood as the act of conception, and (b) understood as the content of that act. I begin with this suggestion, taking up first the attendant and then the modification model. I then show that this distinction introduces clarity into three traditionally controversial aspects of Hume's position.

ALL the perceptions of the human mind resolve themselves into two distinct kinds, which I shall call IMPRESSIONS and IDEAS. (T 1)

Given this menu at the opening of the Treatise, we must ask whether the sentiment which attends the enlivened conception is annexed to an impression or to an idea. The attendant itself is an impression and thereby the source of the liveliness of the believing conception. By itself, we are told, conception has no force and vivacity. Throughout the Treatise Hume ranges "mere conception" on the side of thinking, in the easily perceivable division between feeling and thinking (T 2), and from this we can conclude at least provisionally that this conception is itself an idea, which is joined to an impression to produce our assent. In this light the conception and the idea are simply two names for the "parts and composition" (compare T 94-95, 628) of belief, or what I will call here the content of an act of the mind, by which I mean those elements of such an act which indicate the direction of the mind to an object. ⁶ It is this content which does not change in the transformation from mere conception to belief. The direction to a particular object persists. If belief is no more than conception which is annexed to or...