Constancy and Coherence in 1.4.2 of Hume's Treatise: The Root of "Indirect" Causation and Hume's Position on Objects Stefanie Rocknak* Abstract This article shows that in 1.4.2.15-24 of the Treatise of Human Nature, Hume presents his own position on objects, which is to be distinguished from both the vulgar and philosophical conception of objects. Here, Hume argues that objects that are effectively imagined to have a "perfect identity" are imagined due to the constancy and coherence of our perceptions (what we may call 'level 1 constancy and coherence'). In particular, we imagine that objects cause such perceptions, via what I call 'indirect causation.' In virtue of imagining ideas of objects that have a perfect identity, our perceptions seem to be even more constant and coherent (what we may call 'level 2 constancy and coherence'). Thus, in addition to seeing that Hume is presenting his own position on objects in this section of the Treatise, we see that he is working with a previously unrecognized kind of causation, i.e., indirect causation, and that he has two kinds of constancy and coherence in mind: level 1 and level 2. * 381⁄2 West End Ave., Oneonta, NY 13820, USA. Email: rocknaks@hartwick.edu Most Hume scholars think that Hume is presenting the vulgar (i.e., "everyday") account of objects in 1.4.2 of the Treatise-at least up until he discusses the philosopher's rejection of it.1 I disagree. In partial agreement with Kemp Smith,2 I argue that Hume's discussion of the constancy and coherence of impressions in 1.4.2 contains an implicit presentation of his own non-vulgar, and non-philosophical, position. In the course of doing so, I show that Hume employs a very unusual kind of causation; what I call "indirect causation." As a result, we are given an entirely new way to read Hume's position on objects in 1.4.2 of the Treatise. 1. Overview of the Beginning of 1.4.2 In the opening paragraph of Treatise, 1.4.2, Hume announces that his project is not metaphysical, assuring us that he will not attempt to give an argument for or against the existence of objects, or what he refers to here as "bod[ies]."3 Rather, he promises to give us an account of how we come up with our ideas of objects. In particular, he begins by claiming that a properly conceived-of object must have the properties of continuity and distinctness, where, he claims, if we think that continuity obtains of an object we will naturally think that distinctness obtains of the same object and vice versa (1.4.2.2). However, contrary to popular (vulgar) belief, we do not use our senses to come up with these ideas (1.4.2.3–13). Indeed, as far as this matter is concerned, we must be skeptical with regard to the senses, and thus, the title of this section. Nor though do we use reason to come with such ideas (1.4.2.14). Rather, our ideas of mind-independent objects are imagined. However, there are three ways that we can imagine ideas of objects: (1) We may properly imagine ideas of objects based on the constancy and coherence of our impressions (i.e., the process this essay is devoted to explaining); (2) We may imagine that objects are identical to impressions; this is the vulgar view, which is fraught with problems;4 and (3) Or we may, using reason and the imagination, mistakenly conclude that objects are mind-independent. This is the philosopher's position, where the philosophers think that they are using just reason to conclude that mindindependent objects exist. In all three cases we are presented with skeptical positions; we do not sense mind-independent objects, nor do we reason our way to them. We must, in all three cases, imagine them. In the course of 1.4.2.15–24, Hume discusses why the imagination is responsible for our ideas of objects that admit of continuity and distinctness in terms of a discussion of the "constancy and coherence" of impressions. Here is where our explication begins. However, we must first briefly explain what Hume meant by "perfect identity." 2. Perfect Identity Hume introduces perfect identity in Treatise, 1.4.2.24, which culminates in the statement in 1.4.2.30 that the two essential properties of identity are invariability and uninterruptedness (Hume repeats this claim in 1.4.6.6). Moreover, ideas admit of perfect identity, not impressions, and not mind-independent objects (1.4.2.29, 1.4.6.6). Also, Hume tells us in 1.4.2 that the properties of invariability and uninterruptedness are imagined (1.4.2.29–30). As a result, they could not be impressions-we do not imagine sense impressions (1.1.1–3). Nor could they be mind-independent properties since, by definition, such things are not imagined. Thus, uninterruptedness and invariability must be ideas, and so, squaring with Hume's explicit remarks to this effect, perfect identity must be an idea, particularly, an imagined idea. Hume proceeds to tell us that the vulgar conception of objects clearly "lacks" one of these essential qualities of perfect identity, i.e., the imagined property of uninterruptedness (1.4.2.31). He even makes this point a bit earlier in 1.4.2, where in the course of giving a preview of the vulgar position he writes: "this interruption [of the perceptions'] existence [in the case of the vulgar conception of objects] is contrary to their perfect identity" (1.4.2.24; emphasis added). Moreover, Hume specifically refers to the vulgar conception of objects as "improper" in 1.4.6.7. This is the case because all vulgar attempts to imagine an object as being invariable and interrupted are "ficti[cious]" as opposed to being properly imagined. As such, we should realize that there are correct and incorrect applications of the idea of perfect identity, where the vulgar engage in an improper application.5 Immediately, then, we know that at least Parts 2 and 3 of Hume's four-part system (where he explicitly discusses the vulgar position, i.e., 1.4.2.31–40) could not be an explanation of how we successfully come up with an idea of perfect identity. The reason for this is simple: the vulgar cannot effectively imagine an idea of an invariable and uninterrupted object.6 It must be noted however, that the vulgar may, very briefly, entertain an idea of perfect identity that is "confound[ed]" with a succession of resembling objects (1.4.2.34). This idea of perfect identity is a result of the vulgar "fixing their thought" (1.4.2.33) for an extended period of time. In turn, the vulgar (thanks to the help of the imagination) conceive of an idea that is uninterrupted and invariable. But because such ideas only occur in those rare cases where we "fix our thought," they are fleeting.7 And thus, Hume claims, the vulgar cannot effectively imagine an idea of perfect identity (1.4.2.36–37). But where in 1.4.2 does Hume discuss cases where we can effectively imagine an idea of perfect identity? If there are such places, then we know that they do not pertain to the vulgar position. Nor could they pertain to the philosophical position. For according to the philosopher, we allegedly use just reason (and not the imagination) to conclude that invariable and uninterrupted objects exist (1.4.2.43–57).8 Hume's discussion of the constancy and coherence of our impressions fits the bill. Here Hume does indeed explain how we can effectively imagine ideas that we think admit of perfect identity. In fact, the entire point of this portion of the Treatise is to show how the regularity of our impressions enables us to properly imagine such ideas. However, Hume's discussion of the constancy and coherence of our impressions involves a discussion of how we imagine ideas of objects that are continuous and distinct, not uninterrupted and invariable. Therefore, it might seem that Hume does not have perfect identity in mind. But for our purposes, we may overlook this discrepancy. For recall that Hume opens 1.4.2 by claiming that he wants to explain how we do effectively come up with certain ideas of objects, particularly "opinions" of continuous and distinct objects (1.4.2.14). Here, as explained above, he concludes that we neither sense such ideas nor reason our way to them. Rather, we imagine them. Meanwhile, as we just saw, we do not sense, nor reason our way to an idea that is thought to admit of invariability and uninterruptedness. Rather, we imagine it. Moreover, such an idea is the proper conception of identity. Thus, at least generally speaking, imagining an idea that is continuous and distinct seems to play the same role that imagining an idea that is invariable and uninterrupted does. Both seem to be cases of perfect identity.9 Thus, it is clear that Hume's account of constancy and coherence must not be conflated with Hume's account of the vulgar position. For again, the former account concerns how we may effectively imagine an idea of an object that seems to be continuous and distinct, i.e., is uninterrupted. And this is precisely what the vulgar can't do, at least not effectively. Nor, as explained above, should it be conflated with the philosopher's position. Thus, however implicitly, Hume is presenting a third position here, which, we may assume, represents his position since there is absolutely no indication that it belongs to some other school of thought or individual.10 The question now is what exactly is this third position, i.e., Hume's position? 3. Level 1 Constancy and Coherence First, we need to emphasize that, according to Hume, we never imagine impressions. However, in the initial stages of Hume's discussion of constancy and coherence, he repeatedly refers to a process where, if not read with extreme care, seems to suggest that we do imagine impressions that admit of continuity and distinctness: Since all impressions are internal and perishing existences, and appear as such, the notion of their distinct and continu'd existence must arise from a concurrence of some of their qualities with the qualities of the imagination; and since this notion does not extend to all of them, it must arise from certain qualities peculiar to some impressions. 'Twill therefore be easy for us to discover these qualities by a comparison of the impressions, to which we attribute a distinct and continu'd existence, with those, which we regard as internal and perishing. (1.4.2.15; emphasis added) Here, Hume seems to clearly be saying that impressions admit of the imagined properties of continuity and distinctness. In fact, and seemingly more damning still, he immediately continues: We may observe, then, that 'tis neither upon account of the involuntariness of certain impressions as is commonly suppos'd, nor of their superior force and violence, that we attribute to them a reality, and continu'd existence, which we refuse to others, that are voluntary and feeble. (1.4.2.16; emphasis added) We appear to "attribute a reality" (i.e., a distinctness from our perceptions) and "continu'd existence" to impressions, not ideas. By doing so, Hume seems to be endorsing some version of the vulgar position on objects (as opposed to his own position, as I argued above). For the vulgar mistakenly think that impressions are both uninterrupted and invariable, and so, they think that objects are impressions, i.e., objects are what we sense. The only difference is that here Hume is referring to a process where we attribute the properties of continuity and distinctness to impressions, not uninteruptedness and invariability. But this is not a significant difference. Rather, as we saw above, continuity and distinctness are, for our purposes, interchangeable with uninterruptedness and invariability. So, is Hume really discussing the vulgar position here after all, despite my claims to the contrary? No. To see why, we should first realize that immediately after these passages, he dismisses the "vulgar opinion" that the "involuntariness" and the "superior force" of certain impressions prompt us to "attribute to [impressions] a distinct and continu'd existence" (1.4.2.15). This means that he is rejecting at least part of the vulgar position here while appearing to retain another part of it, i.e., what appears to be his claim that we attribute the imagined properties of continuity and distinctness to impressions. We may conclude that he actually rejects all of the vulgar position. For, from here on out in his discussion of constancy and coherence, Hume stops referring to impressions that admit of continuity and distinctness, and instead consistently refers to "objects," or "bodies." In all instances in this portion of the Treatise, these words apply to ideas, not impressions. For throughout his discussion of constancy and coherence, Hume argues that we imagine that objects, i.e., bodies, admit of continuity and distinctness. But earlier in the Treatise, i.e., in 1.1.1–3, Hume makes it clear that we never imagine impressions. Rather, we imagine (and remember) ideas, which are always less "vivacious" than their corresponding impressions. Therefore, he must mean an idea when he mentions objects and bodies in this portion of the Treatise. Having removed what could be a major obstacle in our reading-i.e., the mistaken assumption that Hume thinks that we imagine that the properties of continuity and distinctness belong to impressions, not ideas-let's examine how Hume thought this imaginative process worked. Immediately after claiming that the "IMAGINATION . . . must now be the subject of our enquiry" (1.4.2.14), Hume explains that first, he must (1) determine what impressions enable us to imagine objects (i.e., ideas) that are continuous and distinct and following; and (2) determine just what it is about such impressions that allows us to imagine objects as being continuous and distinct. In particular, because the imagination grants continuity and distinctness to objects, based on some impressions and not others, it must be the case that this former set of 'some' impressions has certain qualities that the latter lack. What then, are these special qualities? As noted above, contrary to the vulgar opinion, Hume explains that it is not the "involuntariness" nor the "force and violence" (1.4.2.16) of certain impressions that causes us to imagine objects that are continuous and distinct. Although pains and pleasures are involuntary, as well as, occasionally, forceful and violent, we generally do not conceive of pains and pleasures as being objects, much less as being objects that admit of continuity and distinctness. Rather, we tend to think that pains and pleasures are just intermittent sensations (1.4.2.16). Having established as much, Hume concludes that all those objects that we do imagine as "continu'd" (1.4.2.18) and so, one may conclude, as distinct as well (1.4.2.2), are derivative of impressions that "have a peculiar constancy, which distinguishes them from the impressions, whose existence depends on our perceptions" (1.4.2.18). In other words, the properties of continuity and distinctness seem to presuppose the property of constancy in certain impressions. Thus, 'constancy' is one of the special qualities that we are looking for. As a result, if we imagine an object that is continuous and distinct, we must be basing our imagined idea of the object on impressions that are constant, where this constancy is not a function of our constantly having a certain impression. Instead, this 'constancy' obtains despite any interruptions that we may experience while we are having such impressions. This is what Hume means when he claims in the line cited above that there are certain constant impressions whose constancy is to be distinguished from those impressions whose "[constant] existence depends on our perception." For instance, Hume explains, no matter how often he turns away from certain objects (such as mountains, houses, trees, tables, books and papers), when he senses them again, they always appear the same (1.4.2.18). But are constant impressions sufficient for our imagined conception of objects that are continuous and distinct? No, Hume explains, impressions must be coherent as well. This is the case because, although certain bodies (i.e., objects) may change slightly over time, we nevertheless tend to think of such things as being the same body. For instance, I am certain that the brown rotting orange in my refrigerator is the same orange that was in the fridge last month, although the impressions that I have of it today are quite different from the impressions that I had of it last month. Hume sketches how and why this is case by introducing a "kind of reasoning from causation" (1.4.2.19): Bodies often change their position and qualities, and after a little absence or interruption may become hardly knowable. But here 'tis observable, that even in these changes they preserve a coherence, and have a regular dependence on each other; which is the foundation of a kind of reasoning from causation; and produces the opinion of their continu'd existence. (1.4.2.19; emphasis added) Despite the changes a body, say, an orange, may experience, these changes cohere in terms of having a "regular dependence on each other." This coherence provides a "foundation" for a "kind" of causal reasoning. In turn, this peculiar kind of causal reasoning enables us to imagine an object that has a continued existence. Moreover, this coherence is a property of certain impressions, for example, the multiple impressions of the rotting orange: "the opinion of the continu'd existence of body depends on the CONSTANCY and COHERENCE of certain impressions" (1.4.2.20; emphasis added). However, just what this mysterious kind of reasoning from causation is, and why Hume abruptly throws it into the mix here, is not yet clear. Why does he characterize this process in terms of a peculiar kind of causal reasoning, rather than causal reasoning simpliciter? 4. Level 2 Constancy and Coherence We can answer this question if we continue to work our way carefully through the text, beginning with an examination of Hume's account of external v. internal impressions. Hume explains that, although certain internal impressions (such as pains and/or emotions) are coherent, they are coherent in a way that is different from the impressions that seem to be derivative of those objects (i.e., ideas) that we imagine to be continuous and distinct (1.4.2.20). In particular, Hume explains, although our internal impressions do have a certain "mutual connexion with and dependence on each other," it is just not the same kind of connection and dependence that occurs with those impressions that we "discover in bodies" (1.4.2.20), i.e., those bodies that admit of continuity and distinctness. What then, is this special dependence and connection that impressions discovered in bodies enjoy, but internal impressions do not? To answer this, Hume explains that in the case of internal impressions, we do not need to "suppose" (1.4.2.20), i.e., imagine,11 that they continue to exist in virtue of obtaining of some internal 'object' that continues to exist when we are not perceiving it. However, in the case of those impressions that we discover in bodies, we do need to suppose that the object that we find them in does. For instance (thankfully enough), I need not suppose that after my headache has been wiped-out by the appropriate medicine-such that I am no longer having headache impressions-that it still exists somewhere, ready and waiting to attack at the most inopportune moment. However, "the case is not the same with external objects" (1.4.2.20). For instance, I generally do assume that my car continues to exist when I am not having impressions of it. As a result, Hume argues, external objects must be imagined as being continuous (and so, distinct as well), despite our interrupted perceptions of them; "[External objects] require a continu'd existence, or otherwise lose, in a great measure, the regularity of their operation" (1.4.2.20; emphasis added). Thus, because we need not imagine that internal impressions occur as a result of some continuous (and so, distinct) object (e.g., a headache that continues to exist somewhere when I am not having it), such internal impressions do not enjoy the same kind of special dependence and connection-or in other words, the coherence-that impressions that appear to be caused by external objects enjoy. My impressions of my car cohere in a manner that is different from the manner in which my headache impressions cohere, in virtue of the fact that I imagine my car to be continuous (and thus, distinct as well), while I do not do so with my headache. Speaking of headaches, Hume seems to have abruptly reversed his position here. For earlier, as explained in §3, we saw that the coherence that obtains of certain impressions "is the foundation of a kind of reasoning from causation, and produces the opinion of a continu'd existence [and thus a distinct existence]" (1.4.2.19; emphases added). According to this line of thought, continuity (and thus distinctness) presupposes coherence. Yet here, in regard to the distinction he sets up between internal and external impressions, Hume claims that the special coherence obtaining of impressions that we discover in bodies is a function of our thinking of such objects as being continuous (and thus, distinct). So, according to this line of thought, coherence presupposes continuity (and thus distinctness). Which is it, then? The answer to this puzzle, as we will see shortly, is both, although at this point in the text, Hume is not nearly as explicit in these matters as he could be. 5. The Porter in the Room and Mail on the Desk To work our way towards Hume's more explicit account of how continuity (and thus distinctness) could both presuppose and be presupposed by the coherence that obtains of certain impressions, we need to examine three examples that Hume presents pertaining to causality and reality. Here Hume returns, although in a roundabout manner, to that mysterious kind of causal reasoning mentioned above (recall §3 of this essay). I say 'roundabout' because in the course of explaining these three examples, he presents instances of causal reasoning that are meant to stand in contrast to the kind of reasoning from causation introduced earlier in regard to coherence. At this point in the text, Hume is still concerned with the continuity (and thus, distinctness) that we must ascribe to external objects in order to think of their impressions as being coherent in a way that internal impressions are not. For although by this point he has located the two special properties that belong to impressions (constancy and coherence) that enable us to imagine an object (i.e., an idea) as continuous and distinct, he is nevertheless certain that these properties could not be fully responsible for the idea that the objects around him afford a continued (and thus distinct) existence (1.4.2.20). So what else is needed? Hume's answer is reasoning from cause and effect, although the reasoning from causation that he discusses here turns out to be fundamentally distinct from the kind of reasoning from causation brought up in regard to the coherence that obtains of impressions. To see why, consider the underlying point of all three examples presented in 1.4.2.20. Based on past experience, or what he refers to here as "common experience," he comes to believe in certain causal relationships. More specifically, if p then q, where if he has a present impression p-or in terms of the examples he gives here, respectively, the noise of a door moving (X1), a porter in his room (X2), and a letter on his desk (X3)-he may conclude q and concomitantly, believe in q's continuous (and thus distinct) existence. Or in terms of the examples he gives here, q would be, respectively, the door existing, (Y1), the stairs existing (Y2), and posts and ferries existing (Y3). As a result, to believe that, e.g., the posts and ferries do not continue to exist when he receives a letter on his desk, would be a "contradict[ion] to common experience" (1.4.2.20; emphasis added). 12 However, Hume immediately infers that this brand of reasoning from causation, which is necessarily based on "common experience," is simply not enough to grant us the idea of an object that admits of continuity (and thus distinctness). For, the implication is, although it certainly reassures us of the continued (and thus distinct) existence of such objects, it is the mysterious kind of reasoning from causation mentioned earlier that enables us to initially think of objects as being continuous and distinct. Thus, we might conclude that this special kind of causal reasoning is epistemologically prior to the reasoning from causation that is based on common experience. For, if we did not first imagine objects, say X and Y, as being continuous and distinct, we could not conceive of X and Y as being mind-independent objects, existing distinct from our thought, and, it seems, from each other. Concomitantly, we could not conceptualize them in terms of a causal relationship, i.e., if X then Y. However, in regard to these examples, Bennett claims that "the notion of 'contradiction' has no place here unless I already accept a large body of theory: the proposition that I inhabit a world of objects, many hypotheses about their general behavior, and some hypotheses of the form 'I have perceptions of kind K only when in the presence of objects of kind K'." In fact, Bennett concludes, "This is the greatest case yet of Hume's failure [to properly] set the scene for an analysis of objectivity-concepts."13 However, as suggested above, Hume surely does seem to have a "large body of theory" in place regarding the nature of objects; this is precisely why he must introduce the notion of a special "kind of reasoning from causation" (1.4.2.19) to explain how and why we believe we live in a world of mind-independent objects. In fact, the remainder of 1.4.2 is meant to illustrate just how this unusual reasoning from causation properly takes place versus (1) how it does not take place, specifically, in terms of a "vulgar" misconception of objects, where impressions are identified with objects; and (2) how it is misunderstood by the philosophers. 6 . A Kind of Reasoning from Causation: More Detail To see that Hume thinks that reasoning from causation that is based on common experience is not capable of providing us with our initial notion of a continued (and thus distinct) object, note that immediately after his discussion of the three examples mentioned above, he writes: But tho' this conclusion from the coherence of appearances may seem to be of the same nature with our reasonings concerning causes and effects; as being deriv'd from custom, and regulated by past experience [as illustrated by the three examples given above]; we shall find upon examination that they are at the bottom considerably different from each other, and that this inference arises from the understanding, and from custom in an indirect and oblique manner. (1.4.2.21; emphases added) Indeed, this "conclusion from the coherence of appearances" does seem to be like the causal reasoning derived from custom explained above in terms of the three examples. However, it is not. In fact, this conclusion from the coherence of appearances is, Hume clearly states, "considerably different" from causal reasoning that is derivative of custom. In particular, although this conclusion does "arise" from custom, it does so in a decidedly "indirect and oblique manner." In fact, this strange "conclusion derived from the coherence of appearances" is a direct reference to the kind of reasoning from causation mentioned earlier in regard to the coherence that admits of impressions (§3). This must be the case for two reasons: (1) such a "conclusion" could not be a reference to the causal reasoning that takes place in terms of the three examples summarized above in §5. This is because, as noted, all three of these examples illustrate cases where the causal reasoning at hand is directly derivative of custom, while the "conclusion" noted above is clearly not; (2) Nevertheless, this conclusion derived from the coherence of appearances must constitute some kind of causal reasoning because Hume specifically refers to it here as an "inference." According to Hume, there are only two kinds of inference, demonstrative and causal. Since there is no evidence to suggest that Hume has a demonstrative inference in mind here, he must, by default, have a causal inference in mind. Finally, we saw in §3 that a certain kind of reasoning from causation, has a "foundation" (1.4.2.19) in the coherence that we discover in impressions. When supported in this manner, causal reasoning, allows us, somehow, to think of an object as continued (and thus distinct). In other words, this peculiar kind of reasoning from causation is in fact a conclusion that is based on the coherence that admits of certain impressions, which is precisely what Hume seems to be referring to in the paragraph cited above, namely, "this conclusion from the coherence of appearances" (1.4.2.21; emphasis added). Consequently, it is clear that Hume has decisively switched gears in the paragraph cited above. He moves from discussing causal reasoning based on experience that allows us to think of an object as being continuous and distinct to a kind of reasoning from causation that is not directly based on experience, and as such, allows us to imagine an object (i.e., an idea) as being continuous and distinct. And so, as noted, I suggest that the former process presupposes the latter process, which, contrary to Bennett's claim, does seem to "set the scene for an analysis of objectivity-concepts."14 For ease of reference, we may refer to this latter peculiar kind of causal reasoning as 'indirect' causal reasoning. However, Hume immediately tells us that some might complain that it seems that we could never come up with any kind of "regularity" that goes beyond the regularity of our perceptions. For "'twill readily be allow'd that . . . nothing is ever really present to the mind, besides its own perceptions" (1.4.2.21). Because all ideas are ultimately derivative of impressions, any regularity that impressions admit of, must, it seems, originate in those impressions. To argue otherwise, it seems, would be a contradiction (see also 1.2.6.8-9, 1.4.2.3). As a result, it seems that this special kind of reasoning from causation (or, in other words, what we may identify with "this conclusion from the coherence of appearances") which is not directly derivative of custom, is a non-starter. But Hume immediately continues: 'tis evident, that whenever we infer the continu'd existence of the objects of sense from their coherence, and the frequency of their union, 'tis in order to bestow on the objects a greater regularity than what is observ'd in our mere perceptions. We remark a connexion betwixt two kinds of objects in their past appearance to the senses, but are not able to observe this connexion to be perfectly constant, since the turning about of our head, or the shutting of our eyes is able to break it. (1.4.2.21; emphasis added) Based on the constancy (which Hume refers to here as a kind of "frequency") and coherence that we do glean from impressions-which is not perfect, i.e., is not "perfectly constant,"15-we imagine an object to be continuous (and thus distinct). By using that special kind of reasoning from causation which is not directly based on experience, we "infer" that some continuous and distinct object must be the source or, in other words, the cause of our impressions, in order to explain the constancy and coherence that our impressions do clearly admit of. For how else could my impressions of say, a mountain, be constant and coherent (no matter how many times they are interrupted), unless there is some continuous and distinct object causing those impressions? Here then, is the "conclusion from the coherence of appearances."16 And this, as we saw above, is equivalent to a certain unusual kind of causal reasoning. Or, in other words, what Hume refers to in the line just cited, as an "infer[ence]." In turn, in virtue of imagining an object to be continuous (and thus distinct), such objects simultaneously admit of a "greater regularity than what is observ'd in our mere perceptions." In the immediately following passage, Hume claims that we must imagine that "insensible" objects continue to exist (1.4.2.21; emphasis added), despite our interrupted sensations of them. Thus, Hume could not be clearer that this continuous (and thus distinct) insensible object that we imagine could not be a function of custom. By definition, we never have an impression of an insensible object. Moreover, we never have an impression or impressions of an object that is continuous and distinct (recall §1 of this essay). So, naturally, when we imagine a continuous and distinct object to be the cause of our constant and coherent impressions, we are imagining a cause that we have never actually experienced. Thus, it simply follows that this kind of causal reasoning is, as Hume warned us above, "considerably different" from the causal reasoning that is directly a function of custom (see also 1.3.2.2). As a result, Hume tells us, this special kind indirect causal reasoning takes place thanks to the "co-operation of some other principles" (1.4.2.21; emphasis added). To help explain what these other principles are, particularly in terms of how they may be driven by an indirect and oblique kind of custom, Hume writes: I have already observ'd, in examining the foundation of mathematics, that the imagination, when set into any train of thinking, is apt to continue, even when its object fail it, and like a galley put in motion by the oars, carries on its course without any new impulse. This I have assign'd for the reason, why, after considering several loose standards of equality, and correcting them by each other, we proceed to imagine so correct and exact a standard of that relation, as is not liable to the least error or variation. (1.4.2.22; emphases added) Mathematics has an epistemological "foundation" just as the notion of continuity (and thus distinctness) does.17 In particular, although we might-evidently by way of impressions-have certain "loose standards of equality," we may, after comparing a number of such loose standards, imagine "a[n] exact standard of that relation [of equality]." Thus, we may think of our "loose standards of equality" in terms of our newly-minted "precise" standards; the former are evaluated in terms of the latter. And so, our "exact" notion of equality is, in an indirect manner, based on our impressions; it is just that the imagination has elevated our notion of equality to a level that we never actually experience in the world. Having established this, Hume explains that an analogous process occurs when it comes to imagining an object to be continuous (and thus distinct): The same principle makes us easily entertain this opinion of the continu'd existence of body. Objects have a certain coherence even as they appear to our senses; but this coherence is much greater and more uniform, if we suppose the objects to have a continu'd existence; and as the mind is once in the train of observing an uniformity among objects, it naturally continues, till it renders the uniformity as compleat as possible. The simple supposition of their continu'd existence suffices for this purpose, and gives us a notion of a much greater regularity among objects, than what they have when we look no farther than our senses. (1.4.2.22; emphases added) Just like equality, coherence is initially perceived somewhat "loose[ly],"18 or as Hume puts it here: "objects have a certain coherence even as they appear to our senses." However, as a result of supposing, or, in other words, imagining that insensible continuous and distinct objects cause our impressions, these impressions take on a "greater and more uniform coherence." Our impressions seem more "compleat." For instance, in virtue of imagining a continuous and distinct mountain (which I have never had an impression of), as the cause of my impressions, my impressions subsequently seem even more constant and even more coherent. They take on a greater regularity. 7. Summary: Hume's Position At this point, it should be clear that Hume does not have the vulgar in mind throughout his discussion of the constancy and coherence of impressions. Not only does this discussion concern a case where we may effectively imagine perfect identity, but the process that enables us to do so is entirely different from the process that occupies the vulgar mind. In particular, no assumption is made that sense perceptions are objects, an assumption that the vulgar are deeply committed to. Second, objects, via indirect causation, are imagined to be causes. However, the vulgar never imagine that objects are causes, much less employ indirect causation. Third, the vulgar are only mentioned once in this discussion, where Hume specifically distances himself from their position (1.4.2.15; recall §3 of this essay). Thus, the text simply does not support the assumption that Hume has the vulgar in mind here. Nor could Hume be discussing the philosophical position. This is the case for two reasons. First, the philosophical position only comes about via a rejection of the vulgar position. But there is no evidence that thinking in terms of indirect causation is motivated by such a rejection. Second, the philosophers mistakenly think that reason alone justifies their conclusion that mind-independent objects actually exist. However, in the constancy-coherence portion of 1.4.2, we see that we must imagine that mind-independent objects exist. Thus, Hume must be presenting a third position here, although he never explicitly says as much. In particular, we may characterize the "loose" (1.4.2.22) or "imperfect" (1.4.2.21) constancy and coherence that we initially apprehend in impressions as Level 1 constancy and coherence. Meanwhile, the more "regular" (1.4.2.22) way in which impressions appear to us in virtue of imagining continuous and distinct objects, may be characterized as Level 2 constancy and coherence. Having established this, the puzzle raised in §4 of this essay may finally be answered: continuity (and thus distinctness) does indeed presuppose Level 1 coherence (as well as constancy). For it is the initial and incomplete constancy and coherence of our impressions that somehow inspires us to imagine continuous and distinct objects as being the "insensible" causes of such initial impressions (1.4.2.22).19 In fact, it is in precisely the respect that such Level 1 constancy and coherence prompts us to imagine continuous and distinct objects as the cause of our impressions that this special kind of reasoning from causation is "indirect[ly] and oblique[ly]" rooted in experience (4.2.21). It is guided by Level 1 constancy and coherence. Meanwhile, Level 2 coherence (and constancy) does indeed presuppose our imagined notions of continuous and distinct objects. For in virtue of imagining continuous and distinct objects as being the respective causes of external impressions, such external impressions admit of a more "uniform" (1.4.2.22) coherence (and constancy) than internal impressions. And so, in this qualified respect, constancy and coherence both presupposes and is presupposed by continuity (and thus distinctness). In fact, it seems clear enough that, according to Hume, and contrary to Bennett, this special kind of reasoning from causation must be epistemologically prior to the reasoning from causation that is a function of custom, which, at best, reassures us of an object's continuous and distinct existence. For, it seems, if we did not first imagine objects, say X and Y, as being continuous and distinct, we could not conceptualize causal relations as obtaining between separate, mind-independent things. Notes Earlier versions of this essay were presented at New Philosophical Perspectives on Hume, University of San Francisco, San Francisco, CA (2007), NY/NJ Consortium in the History of Modern Philosophy, New York (2006), and at Upstate New York Early Modern Workshop, Syracuse University, Syracuse, NY (2005). Portions of an earlier version of this article appear in Stefanie Rocknak, Imagined Causes: Hume's Conception of Objects. 1 See, for instance, H. H. Price, Hume's Theory of the External World (Oxford: Oxford University Press, 1940); Jonathan Bennett, Locke, Berkeley, Hume: Central Themes (Oxford: Oxford University Press, 1971); Barry Stroud, Hume (London: Routledge, 1977); Mark Collier, "Filling in the Gaps: Hume and Connectionism on the Continued Existence of Unperceived Objects," Hume Studies 25.1–2 (1999): 155–70; and Peter Kail, Projection and Realism in Hume's Philosophy (Oxford: Clarendon Press, 2007). 2 Kemp Smith, The Philosophy of David Hume: A Critical Study of its Origins and Central Doctrines (New York: Macmillan, 1964), 473. 3 David Hume, A Treatise of Human Nature, ed. D. F. Norton and M. J. Norton (Oxford: Oxford University Press, 2002), 1.4.2.1; hereafter references to the Treatise are cited in the text. 4 Cf. Stefanie Rocknak, "The Vulgar Conception of Objects in 'Of Skepticism with Regard to the Senses'," Hume Studies 33.1 (2007): 67–90. 5 Moreover, any idea that we imagine to be invariable and uninterrupted is not actually invariable and uninterrupted, we just imagine that this is the case; recall §1 of this essay. 6 Cf. Rocknak, "The Vulgar Conception of Objects." 7 Cf. Rocknak, "The Vulgar Conception of Objects." 8 Although, Hume points out, the philosophers do unknowingly appeal to the imagination (1.4.2.52). 9 For a more nuanced explanation of the relationship between these two pairs of properties, see Stefanie Rocknak, Imagined Causes: Hume's Conception of Objects, The New Synthese Historical Library, vol. 71 (Dordrecht: Springer, 2012). 10 Cf. Smith, The Philosophy of David Hume, 473. 11 We may conclude that 'suppose' is interchangeable with 'imagine,' given Hume's earlier claim that the properties of continuity and distinctness must be imagined (1.4.2.14). 12 In more detail, the first example proceeds as follows: Hume explains that he may conclude that the noise of a door indicates that someone (probably a porter) is on the other side of it, pushing it, although he did not actually see the door move: "I have never observ'd that this noise cou'd proceed from anything but the motion of a door; and therefore conclude, that the present phaenomenon is a contradiction to all past experience, unless the door, which I remember on t'other side of the chamber be still in being" (1.4.2.20; emphasis added). This claim is equivalent to the claim: If it is not the case that the door still exists, then what I have just experienced, and concluded as result of that experience, namely, the door existing, contradicts my past experience (recall that 'unless' can be interpreted as 'if not'). Thus, in short, the causal relation derivative of Hume's "past experience" here is: If I hear the sound of the door in my room moving, then there is a door moving, and so, the door exists. The second example proceeds as follows, in so many words: If it is the case that the stairs have been annihilated, then the porter must have somehow floated up to his room, an event that contradicts Hume's past experience. Thus, the causal relationship that is derivative of Hume's past experience here is: If the porter is in my room, then he must have used the stairs to do so, and so, these stairs exist. Third, Hume explains that in order for him to be reading a letter from a friend in a distant location, according to what is "comfortable to my experience in other instances" (1.4.2.20), it must be the case that posts and ferries brought him that letter, and so, these posts and ferries exist. 13 Bennett, Locke ,Berkeley, Hume, 324. 14 Bennett, Locke, Berkeley, Hume, 324. 15 Nor, we must assume, perfectly coherent, although Hume does not explicitly say as much here. However, he does just a bit further on (1.4.2.22). 16 And constancy; see 1.4.2.23. 17 Recall §3, where we discussed Hume's claim that the coherence that admits of impressions "is the foundation of a kind of reasoning from causation" (1.4.2.19; emphasis added). 18 Granted, Hume only mentions coherence here. But shortly after this passage, he includes constancy as well (1.4.2.23). 19 Hume is admittedly vague here in regard to just how this inspiration works; however, he does write that "the explication of [this process] will lead into a considerable compass of very profound reasoning" (1.4.2.23), where that explication is given in Part 1 of his system.