Hume on Memory and Causation

168 HUME ON MEMORY AND CAUSATION In the first part of this paper I shall argue that an examination of Hume's second criterion for distinguishing between ideas of the memory and ideas of the imagination shows that Hume's ideas of the memory are relative ideas corresponding to definite descriptions of the general form, "the complex impression that is the (original) cause of a particular positive idea m and which exactly (or closely) resembles m," where 'm' is a variable ranging over positive ideas (mental images). I shall show that if this is correct, there is a clear basis for distinguishing ideas of the memory both from ideas of the imagination and from beliefs regarding spatially and temporally located objects that are not based upon the memory. But since there is often a significant temporal distance between the impression remembered and the positive component of one's relative idea of the memory, it is incumbent upon me to explain how the remembered impression and the positive idea can be causally related even though they are not temporally contiguous. In the second part of the paper I shall argue that, contrary to his "definitions" of causation in the Treatise,2 Hume took neither spatial nor temporal contiguity to be essential to causation. In Book I, Part I, Section 3 and again in Book I, Part III, Section 5 of his Treatise of Human Nature, Hume provides two criteria for distinguishing between ideas of the memory and ideas of the imagination. I shall refer to these two criteria as "the phenomenal criterion" and "the formal criterion". In this section I shall show that while the phenomenal criterion 169 expresses the means one actually employs in distinguishing an idea of the memory from an idea of the imagination, the formal criterion provides one with insight into the complex structure of an idea of the memory, and therefore allows one to distinguish ideas of the memory from both ideas of the imagination and from other ideas of and beliefs regarding spatially and temporally located objects. In Book I, Part I,- Section 3 of the Treatise, Hume introduces the phenomenal criterion as follows: We find by experience, that when any impression has been present with the mind, it again makes its appearance there as an idea; and this it may do after two different ways: either when in its new appearance it retains a considerable degree of its first vivacity, and is somewhat intermediate betwixt an impression and an idea; or when it entirely loses that vivacity, and is a perfect idea. The faculty, by which we repeat our impressions in the first manner, is called the MEMORY, and the other the IMAGINATION. 'Tis evident at first sight, that the ideas of the memory are much more lively and strong than those of the imagination, and that the former faculty paints its objects in more distinct colours, than any which are employ'd by the latter. When we remember any past event, the idea of it flows in upon the mind in a forcible manner; whereas in the imagination the perception is faint and languid, and cannot without difficulty be preserv'd by the mind steddy and uniform for any considerable time. Here then is a sensible difference betwixt one species of ideas and another. (T 8-9; cf. T 85) It is clear that Hume took this to be a phenomenal criterion, i.e., to specify a sensible characteristic by which one can distinguish an idea of the memory from an idea of the imagination. Not only does he state that he has found "a sensible difference betwixt one species of ideas and another" (T 9), in the parallel 170 passage in Part III, Section 5 he claims to "search for the characteristic [of the idea], which distinguishes the memory from the imagination" (T 85, Hume's emphasis). The characteristic that allows one to "distinguish them in their operation" (T 85) is the difference in the force and vivacity of the ideas involved. Ideas of the memory are "much more lively and strong than those of the imagination," "the former faculty paints its objects in more distinct colours", and ideas of the memory...