What, in the World, Was Hume Thinking? Comments on Rocknak's Imagined Causes
- What, in the World, Was Hume Thinking?Comments on Rocknak's Imagined Causes
Stefanie Rocknak's stimulating, challenging, and highly original new book, Imagined Causes: Hume's Conception of Objects, is helpfully summarized on its back cover as follows:
This book provides the first comprehensive account of Hume's conception of objects in Book I of A Treatise of Human Nature. What, according to Hume, are objects? Ideas? Impressions? Mind-independent objects? All three? None of the above? Through a close textual analysis, Rocknak shows that Hume thought that objects are imagined ideas. But, she argues, he struggled with two accounts of how and when we imagine such ideas. On the one hand, Hume believes that we always and universally imagine that objects are the causes of our perceptions. On the other hand, he thought that we only imagine such causes when we reach a "philosophical" level of thought.
I will examine these two theses about Hume in turn: first, that he held that "objects are imagined ideas"; and second, that he "struggled with two accounts of how and when we imagine such ideas." In order to focus on these two theses, I will be forced to pass over without consideration a wealth of material on related topics that amply repays careful attention. My excuse is that, as Rocknak recognizes and as the back-cover summary goes on to proclaim, accepting even just these two central theses would involve fundamental alterations in our understanding of Hume's philosophy. I will argue that the truth of the two theses would carry major costs to the consistency of Hume's philosophy. I will also argue, however, that these are costs that we, and Hume, can avoid paying. [End Page 59]
I. The First Thesis: Objects as Imagined Ideas
Rocknak's first thesis, that "objects are imagined ideas" for Hume, has three main terms: "objects," "ideas," and "imagine." In order to understand the thesis, therefore, we must first understand how she uses each of these terms.
Objects. Rocknak holds that Hume employs the term "objects" in (by my count) at least five senses in the Treatise, but the sense she employs in the first thesis is what she regards as Hume's dominant sense of the term.1 This sense includes within its scope what he calls "bodies" (29, 75n) and carries the entailment that objects are the causes of our sense impressions (what Hume calls "impressions of sensation"). At the same time, however, this sense of the term does not carry any essential implication that objects have mind-independent existence—since on her view, Hume asserts that there are real bodies but does not "think that objects are mind-independent things; he is not a realist" (xiv).
Ideas. Rocknak grants that Hume uses the term "ideas" to designate mental particulars (xiv) that are either "copied" from impressions or composed of simpler ideas that are each "copied" from impressions (4, 10). She denies, however, that Hume holds "the replication theory" that, she reports, James Beattie, Lorne Falkenstein, and I attribute to him. This "replication theory," as she defines it, is the doctrine that "impressions and ideas must share the exact same [intrinsic] qualities (in differing degrees of vivacity)" (25). Thus, according to Rocknak, Humean ideas that are copied from visual impressions—unlike the visual impressions themselves—do not literally have such qualities as color (23, 65).
Imagine. To "imagine" something, in Hume's typical usage, is to form a non-memory idea of that thing,2 often by combining simpler ideas. To "imagine an idea," in this sense, would thus be to form an idea of an idea—that is, to form a second-order idea of the kind that Hume mentions in the Treatise3 (T 1.3.8.16; SBN 106) as making our thought about ideas possible. When Rocknak writes that objects are "imagined ideas," however, she does not mean that objects are ideas of ideas, but rather that objects simply are ideas constructed by a process of imagination—specifically, of what she calls the "transcendental imagination" (84). They are also imagined as being the causes of sense impressions.
Hence, in saying that "objects are imagined ideas...
