MOVING CARTESIAN BODIES Tyler Doggett•tdoggett@uvm.edu Draft of 7/14 There is a simple argument that Descartes is committed to the thesis that bodies move bodies. The argument runs: MINDS-Descartes is committed to the thesis that minds move bodies.1 PARITY-If Descartes is committed to the thesis that minds move bodies, he is committed to the thesis that bodies move bodies. Hence, BODIES-Descartes is committed to the thesis that bodies move bodies. If the argument is sound, the common view that MINDS is true and BODIES is false it itself false and unstable. If the argument is sound, it illuminates Descartes's views on the role of the senses in justifying metaphysical theses and protecting the mind-body union and illuminates his rationalism and its limits. I argue it is sound. 1 What Descartes is committed to if MINDS and BODIES are true is not that any mind moves any body or that any body moves any other body. He is just committed to the claim that there is some mind that moves some body and that some body moves some body. The claim that some body moves some body is stronger than the claim that bodies have causal powers or that bodies exercise those powers. There are causal powers other than the power to move a body: the power to produce a sensation, the power to hold another body still, etc. Hence, that bodies have causal powers is weaker than the claim that bodies move bodies. I defend that Descartes commits to the stronger claim. 1 I mean "human minds" by "minds" unless otherwise noted. 2 Furthermore, I focus on a certain type of causing to move, namely, initiating motion, as when one billiard ball smashes into and, as a result, moves a stationary one. There are other ways of getting bodies to move: deflecting, channelling, etc.2 I argue for BODIES, largely, by arguing that Descartes commits to bodies initiating motion in other bodies. So, unless otherwise noted, when I use "body-body causation," I mean bodies moving bodies and, more particularly, doing so by initiating motion. And, unless otherwise noted, the bodies I have in mind are medium-sized dry goods and not, for example, the universe. Finally, I say that Descartes "commits" to the theses that minds move bodies and that bodies move bodies. I choose the word advisedly. It raises two issues: a. What does Descartes say about what moves what? b. What does his system imply about what moves what? On (a): I think that what he says quite clearly implies that minds and bodies move bodies. But formidable scholars disagree and I won't place much emphasis on this. The issue comes up mainly when I take up occasionalism, the view that God alone causes effects, at the end of the paper. What I am mainly interested in is (b) and what Descartes's system-his overall metaphysics and epistemology-implies about minds and bodies moving bodies. I argue that Descartes allows certain evidence for certain claims and that evidence implies that minds and bodies move bodies. I also concede that there is a powerful case that the Cartesian system implies that bodies do not move bodies. I argue that the case, mutatis mutandis, implies that minds do not move bodies. 2 Elisabeth highlights ways other than impulsion that a body might move a body. See AT III 660. Descartes, discussing the laws of motion in the Principles, discusses rebounding and deflecting at II.39, 3 In what follows, I defend each of the two premises in my argument for BODIES. The case for MINDS, for Descartes's commitment to the thesis that minds move bodies, is handled first and handled quickly. Although I am convinced that premise is true, it is relatively unimportant. The focus of the paper is on PARITY and those who insist Descartes is an occasionalist-and hence deny the first premise-might accept PARITY. At the end of the paper, I evaluate the case for an occasionalist interpretation of Descartes. The bulk of the paper comes in between. In it, I go through the case for PARITY and some objections to it, showing how none quite succeeds. 2 Descartes says many times and very clearly that minds move bodies and says many times and very clearly things that imply they do. When pressed by commentators to explain how minds move bodies, he never denies that they do; he just asserts that they do. Moreover, he claims to have good evidence that minds move bodies. For example, he writes to Arnauld, That the mind, which is incorporeal, can set a body in motion is...shown to us...by the surest and plainest everyday experience. It is one of those selfevident things which we only make obscure when we try to explain...in terms of other things. (AT V 222; CSMK: 358) That is, minds can move bodies. And the evidence we have that they do is that we perceive cases of minds moving bodies. When Burman asks, "How can the soul be affected by the body and vice versa, when their natures are completely different?" Descartes responds, "This is very difficult II.40 and what follows. 4 to explain; but here our experience is sufficient, since it is so clear on this point that it just cannot be gainsaid" (AT V 163; CSMK: 346).3 Among the ways we experience our minds affecting our bodies is feeling our minds move our bodies. This is the case for MINDS-Descartes is committed to the thesis that minds move bodies: Descartes says that minds move bodies repeatedly. He has what is, by his own lights, good evidence for it. Whenever he is challenged about how minds move bodies, he never denies that they do, which is what you would expect from him if he denies or is unsure of the thesis that minds move bodies. (Garber (1992a) and (1993) and Gorham (2004) argue similarly.)4 3 MINDS is slightly controversial. Norman Kemp Smith, Gary Hatfield, and Jorge Secada, for example, have denied it in Kemp Smith (1953), Hatfield (1979), and Secada (2000). In Machamer and McGuire (2009) and Ott (2009), Peter Machamer, J.E. McGuire, and Walter Ott deny that, in his later works, Descartes goes for the thesis that minds move bodies. Though I disagree with them about MINDS, much of the argument of the paper is acceptable to them. Almost all of the rest of the paper is a defense of PARITY-If Descartes is committed to the thesis that minds move bodies, 3 See, too, this bit of a letter to Elisabeth: "What belongs to the union of the soul and the body [including the mind's power to move a body]...is known very clearly by the senses. That is why people who never philosophize and use only their senses have no doubt that the soul moves the body.... Everyone feels that he is a single person with both body and thought so related by nature that the thought can move the body and feel the things which happen to it" (AT III 691-692 and 694; CSMK: 227-228). 4 There might be another case for the thesis that minds move bodies, namely, that minds' ability to move bodies is crucial for protecting the union of mind and body and, because of this, a good God would have set the world up so that each of our minds moves its own body. For reasons that will become clear in §4, I believe an analogous, equally plausible case can be made for the thesis that bodies move bodies. 5 he is committed to the thesis that bodies move bodies. Kemp Smith, et al. can accept PARITY. They might well endorse it since it can be used to support their own view. Whereas I think MINDS is true and, with PARITY, it implies BODIES-Descartes is committed to the thesis that bodies move bodies, Kemp Smith, et al. think BODIES is false and, with PARITY, that implies MINDS is false. Defending PARITY, I argue The sort of evidence Descartes has supporting the thesis that minds move bodies supports that bodies move bodies. The sort of evidence Descartes has telling against the thesis that bodies move bodies tells against the thesis that minds move bodies. Hence, PARITY The case for-and against-the second premise will be detailed at length. First, the first premise, the case for which is brief and straightforward: The evidence Descartes has for minds moving bodies is sense evidence. That evidence also supports that bodies move bodies. Just as the surest and plainest everyday experience gives us evidence that minds move bodies, so it gives us evidence that bodies move bodies: You feel your finger scratching your bug bite, moving it back and forth. You feel your face pushing into a pillow as you fall asleep.5 It might be objected that this evidence is not, by Descartes's lights, good evidence. The plainest everyday experience, after all, seems to show that the ocean is blue or that some space is empty, and Descartes does not think we have good evidence 5 Gorham accepts MINDS on the basis that Descartes endorses that minds move bodies repeatedly and claims that sensory evidence establishes that they do (Gorham (2004): 390, 403, 405). Gorham denies BODIES but, I think, acknowledges the prima facie case for PARITY. 6 that the ocean is blue or that space is empty. There is no problem for PARITY here or my argument for it. Which isn't to say there is no problem. In some cases, Descartes denies that the senses provide good evidence; in others, he accepts they provide good evidence: What's the difference? This is a real problem-a problem with no obvious solution-precisely because Descartes does seem to think that the senses provide evidence for the thesis that minds move bodies. Descartes is clear on what grounds he holds that minds move bodies-it is evident, thanks to the senses. It might be that these are bad grounds and Descartes should give them up. But in the correspondence with Arnauld (AT V 222; CSMK: 358), Burman (AT V 163; CSMK: 346), and Elisabeth (AT III 691-692 and AT III 694; CSMK: 227 and 228) and elsewhere, it is clear that he doesn't give them up. And those grounds support the thesis that bodies move bodies. So the sort of evidence Descartes has for the thesis that minds move bodies-sense evidence-is equally well evidence for the thesis that bodies move bodies. That is, the first premise in the argument for PARITY is true. 4 Arguing for PARITY-If Descartes is committed to the thesis that minds move bodies, he is committed to the thesis that bodies move bodies. I claimed The sort of evidence Descartes has supporting that minds move bodies supports that bodies move bodies. And noted that sense perception supports both. I then noted it's possible that, by 7 Descartes's lights, sense perception supports neither since, by Descartes's lights, it is no evidence at all. But that is no problem for PARITY or my argument for it. It would show that, by Descartes's lights, sense evidence gives the same support-none-to the theses that minds move bodies and bodies do. More troubling for my argument is the claim that although you feel mind-body causation-feel your desire to raise your arm moving your arm, say-you do not feel body-body causation. You do not, for example, feel billiard balls moving each other about or bumper cars bumping into each other. So Descartes's evidence supporting that minds move bodies does not support that bodies move bodies. Hence, my argument for PARITY is unsound. The billiard ball and bumper car points are of course correct but just establish that some body-body causation is not sense-perceptible. That is consistent with our having sense evidence for other instances of body-body causation. For example, consider a needle pushing into your arm as you get a shot. You can feel the needle-that body- moving your body. Descartes insists on this in Meditation Six when he claims that, to protect ourselves, each person senses whether her body is being "affected by various beneficial or harmful bodies which surround it" (AT VII 81; CSM II: 56). That is, he thinks we feel what external bodies do to our body. He is explicit about these feelings in the Elisabeth correspondence, writing, "everyone feels that he is a single person with both body and thought so related by nature that the thought can move the body and feel the things which happen to [the body]" (AT III 694; CSMK: 228; my emphasis). That is, things happen to the body. Through sense perception, our minds pick up on these things. As long as some of these things happening are bodies moving our bodies, this is a clear 8 statement that we sense bodies moving bodies.6 So there is no difference having to do with our feeling causation between the evidence for minds moving bodies and the evidence for bodies moving bodies. Descartes holds that we feel causation in neither case or we feel it in both. But this sets up a further objection to my argument for PARITY. I claimed that Descartes's evidence for minds moving bodies is sense evidence and sense evidence supports that bodies move bodies. I have responded to objections that we feel causation in neither case and that we feel it only in the mind-body case. But consider the objection that though we feel mind-body and body-body causation, only the former is evidence that minds move bodies or maybe only former is good evidence. The idea is that Descartes makes plain-in Meditation Six, Principles II.3, and elsewhere-that the senses are designed to preserve the mind-body union, not to discover 6 I think the Elisabeth letter makes the important phenomenological point that our minds perceive bodybody interactions as well as mind-body interactions. Compare with Margaret Wilson who writes, How does the experience of pain demonstrate that the body of man is closely united to the mind? In the Meditations Descartes argues that our sensible perceptions must be caused by bodies...But if this line of reasoning shows anything, it shows only that there are bodies that act on our mind; it does not by itself show that we are embodied, 'have bodies.'" ((1999): 218) I think this gets the phenomenology of sense perception wrong. You step on a tack. This hurts. But that is not all we perceive-we don't simply perceive a tack affecting our mind. (What would that feel like?) We perceive that something is damaging our foot-that is, that one body is affecting another body-and pain is the representation of damage. What we perceive is that certain body-body causation is painful. And see Principles II.38's claim that "The fact that air offers resistance to other moving bodies may be confirmed either by our own experience, through the sense of touch if we beat the air with a fan." (AT VIIIA 63; CSM I: 241). That is, we feel one body resisting some other body. And see, too, with Simmons (2008) which points out Descartes holds that that we sense ownership of our bodies ((2008): 90) and need perception of body-body interactions-e.g. flexings of muscles-to perceive this ownership (91). Another phenomenological point: In Meditation Six, the Elisabeth letter, and elsewhere, Descartes insists that our mind can move the body and we are aware of our mind doing so. In some cases, I think, perception of mind-body causation is filtered through perception of body-body causation. Sometimes when you feel your mind moving your body around, what you feel is partly bits of your body moving other bodies around. For example, when you raise your arm underwater, you feel your arm pushing against the water. This is how you know your desire to move your arm is in fact moving your arm. 9 the truth about, say, the nature of bodies or minds. Perhaps, then, Descartes believes that they are especially good at figuring out whether minds move bodies since this talent would be crucial to preserving the mind-body union. It is crucial to preserve your mindbody union, for example, that you be able to figure out whether your mind has pulled your hand-or your head-out of a flame. Perhaps, also, Descartes believes that the senses are not especially good at figuring out whether bodies move bodies since this talent is not crucial to preserving the mind-body union. It is not crucial to preserve your mind-body union, for example, to know that dogs move dirt when digging or that that billiard ball moved this one. If so, the sensory evidence we have for the thesis that minds move bodies is better than the sensory evidence we have for the thesis that bodies move bodies: When the senses attest to mind-body causation, they are doing their job. Not so when they attest to body-body causation. If so, the first premise in my argument for PARITY, namely, The sort of evidence Descartes has supporting that minds move bodies supports that bodies move bodies. is wrong. Partly, the foregoing objection is correct: Descartes holds that to protect the mindbody union, the senses have to figure out whether minds move bodies.7 Partly, it's 7 As Malebranche points out, Descartes is wrong about this. To protect the union, minds needn't perceive causation. They could do so simply by knowing which events follows which. So, for example, to protect your union your mind needn't be aware that fire is burning your hand but only be aware that there's some fire and your hand is in it and, when that happens, bad results follow. Malebranche agrees with Descartes that the senses are designed to protect the mind-body union (Search After Truth I.5.1). Yet they do this job, Malebranche holds, in spite of occasionalism being true (Search After Truth VI.2.3). Whether they need to perceive causation to do a good job is less clear. To be clear, there is no problem for PARITY here, though there might be a problem for the claims that we have good sensory evidence for causation and the claim that perceiving causation is useful to protect our unions. Whether Descartes or Malebranche is right about these claims raises a couple of subtle 10 incorrect: Descartes also holds that to protect the mind-body union, the senses have to figure out whether bodies move bodies. As noted earlier, Meditation Six makes the point clearly: Descartes holds that to protect yourself, you have to be able to tell whether your body is being "affected by various beneficial or harmful bodies which surround it" (AT VII 81; CSM II: 56). When you are in pain, you need to know not just that your body is damaged, you need to know what is causing the damage and how. For example, you need to know whether you are being hurt by external bodies-tacks, flames, bears-or internal ones-dropsy drying out your throat (AT VII 84; CSM II: 58).8 The senses might be quite good at determining that bodies move bodies: That thesis follows from facts the senses are adept at detecting, namely, that a body is harming or benefitting our body. And they might be quite good at determining that bodies move bodies even if, as Descartes routinely insists, they are lousy at metaphysics. 5 Of course, this case for BODIES-Descartes is committed to the thesis that bodies move bodies issues-what it is to perceive causation and whether Malebranche's view is consistent with a nondeceptive, good God-but Descartes doesn't engage with these issues, they are irrelevant to my argument for PARITY, and I put them aside. For more on the relations between Descartes's and Malebranche's views on the role of the senses in protecting the mind-body union, see Simmons (2008). Simmons (1999) contains extended discussion of Descartes's views on the topic. 8 Principles IV.197 supports this, claiming that we perceive body-body causation as when we perceive a sword cutting our body (AT VIIIA 321; CSM I: 284). See, too, Principles I.71 on how sense perception makes us aware of external bodies-and leads us to make erroneous judgments about them (AT VIIIA 3536; CSM I: 218-219). And note that though Descartes singles out various ways in which the senses lead us astray here, he fails to note that they lead us astray when they lead us to judge that bodies affect our bodies, including moving our bodies. Principles IV.191 describes our sensations of touch as an awareness of how other bodies are rubbing nerves near the skin (AT VIIIA 318; CSM I: 281-282). Similar descriptions of our perception of body-body causation are in The Treatise on Man. For example, AT XI 143-144; CSM I: 102103. 11 is defeasible. It might be that Descartes is committed to theses that imply that bodies do not move bodies and that those commitments are stronger or more plausible than his commitment to the theses that bodies do move bodies. If so, then perhaps we shouldn't go for BODIES. Is it so? There are several reasons to think it is. First, the thesis that bodies move bodies seems inconsistent with Descartes's theory of God's role in the material world. Most clearly, that bodies move bodies seems inconsistent with the way that theory is developed in Principles 2:36-45 (AT VIIIA 6167; CSM I: 240-244). In Principles II.36, for example, Descartes writes God is the primary cause of motion....In the beginning...he created matter, along with its motion and rest; and now, merely by his regular concurrence, he preserves the same amount of motion and rest in the material universe as he put there in the beginning. (AT VIIIA 61; CSM I: 240) So far, no problem for the thesis that bodies move bodies. There is a problem for the thesis that bodies are a primary cause of motion, but BODIES doesn't claim that.9 There would be a problem for BODIES if the commitment to God as a primary cause ruled out there being other causes of motion. But it doesn't. In fact, Descartes goes on to single out the laws of nature as causes of motion.10 But that's the rub: He does not single out bodies and, so the objection to BODIES goes, would have if BODIES were true. Moreover, the explanation Descartes gives of the laws of motion show that there is no room for bodies in the causation of motion. For example, explaining the third law of motion, 9 Schmaltz (2007) thoroughly, helpfully discusses Descartes's concept of a primary cause. For interesting criticism, see Platt (2011a): 642-643. 10 The idea of laws as causes is strange. Hattab (2007) and Ott (2009) helpfully spell the idea out, differing on some key points. 12 Descartes writes, [I]t is clear that when he created the world in the beginning God did not only impart various motions to different parts of the world, but also produced all the reciprocal impulses and transfers of motion between the parts. Thus, since God preserves the world by the selfsame action and in accordance with the selfsame laws as when he created it, the motion which he preserves is not something permanently fixed in given pieces of matter, but something which is mutually transferred when collisions occur... (AT VIIIA 66; CSM I: 243) And this echoes II.36: God imparted various motions to the parts of matter when he first created them, and he now preserves all this matter in the same way, and by the same process by which he originally created it... (AT VIIIA 62; CSM I: 240 The objection to BODIES here is that these passages show that God does all the moving of bodies that seems to be done by bodies. Crucially, there is no problem for the thesis that minds move bodies here since the Principles explicitly-see Principles II.40-limits its scope to the material world. So when I argued for PARITY-If Descartes is committed to the thesis that minds move bodies, he is committed to the thesis that bodies move bodies by claiming that The sort of evidence Descartes has telling against the thesis that bodies move bodies tells against the thesis that minds move bodies I was mistaken. The metaphysics of causation Descartes develops in the Principles tells against the thesis that bodies move bodies without telling against the thesis that minds do. About Principles 2:36-45, Garber writes, The picture in [these passages] is reasonably clear: God stands behind the world of bodies and is the direct cause of their motion....[I]n Descartes' 13 new philosophy, the characteristic behavior of bodies is explained in terms of an immutable God sustaining the motion of bodies. I think it is reasonably clear, then, that in the material world, at least, God is the only causal agent. (Garber (1993): 207-208; cf. Garber (1992a): 280-293, Gorham (2004): 402, and Machamer and McGuire (2009): 136) I disagree with Garber's reading. There is another way to read the relevant bit of the Principles so it is consistent with the thesis that bodies move bodies. Consider five pictures of God's place in a pool hall: 1. Deism-God creates a pool table and the laws of motion, gives the balls an initial shove, then the balls do the rest. 2. Conservationism-God creates the pool table and the laws of motion, gives the balls an initial shove, keeps the balls and table from falling out of existence, and then the balls do the rest. 3. Concurrentism-God creates the pool table and the laws of motion, gives the balls an initial shove, keeps the balls and table from falling out of existence, and then knocks the balls against each other. That is, the God pushes the balls and the balls then push other balls. 4. Divine Shovism-God creates the pool table and the laws of motion, gives the balls an initial shove, keeps the balls and the table from falling out of existence, and then pushes each ball Himself. No ball pushes another. ("Divine shove" is from Garber (1993): 208.) 5. Cinematism-God creates the pool table and the laws of motion. The world keeps falling out of existence and God keeps remaking it. But he remakes slightly differently each time. So someone watching the pool table might get the impression that a ball is moving but, really, what's happening is that God makes that ball first in one place, then in another, then in another, etc. Obviously, these pictures are sketches of caricatures. But they needn't be any more detailed since the point I want to make is just that the passages from the Principles that are supposed to tell against BODIES are clearly inconsistent with Deism but also not inconsistent with any of the other positions. Recently, Schmaltz (2007) makes at length the case that Descartes endorses the second option; Platt (2011a) and (2011b) at length makes the case that Descartes goes for the third. If Descartes goes for either, then BODIES is true. I am neutral as to which of those two Descartes goes for or should go for. 14 Defending BODIES doesn't require taking a stand. It just requires rebutting the argument against body-body causation stemming from the Principles.11 To do that, it is enough to show that that case can't come from the Principles alone. The three crucial passages quoted above do not show that the second or third pictures fail to capture Descartes's view. The case against those pictures capturing Descartes's view will have to come at least partly from elsewhere. I will consider some possibilities in the next couple sections. As far as the Principles itself, I think it is not only consistent with the second or third picture but in fact endorses one or the other. For consider the heading of Principles II.43, "The nature of the power which all bodies have to act on, or resist, other bodies." This heading clearly presupposes that bodies have a power to act on other bodies. If the power were God's entirely, wouldn't this article be the place to say so? It doesn't say that. It turns out in Principles II.43 that this power derives from God but not in a way that undermines the thesis that bodies move bodies. Descartes writes, ...[W]e must be careful to note what it is that constitutes the power of any body to act on...another body. This power consists simply in the fact that everything tends, so far as it can, to persist in the same state, as laid down in the first law. (AT VIIIA 66; CSM I: 243) Introducing that first law of motion in Principles II.37, Descartes writes that it follows from God's immutability (AT VIIIA 62; CSM I: 240). So, again, my interpretation of the Principles is that God does "stand behind" the world of bodies in that he created the world of bodies and motion and rest, that world depends on him for its continued existence, and its laws follow from his nature. This is all consistent with BODIES and 11 Compare: We could defend MINDS without deciding whether Descartes goes for the mental analogs of conservationism or concurrentism. 15 MINDS, though, and consistent with God being the primary cause of all motion, that caused by bodies and that caused by minds.12 Support for this interpretation comes from Principles II.40 in which Descartes claims that "all the particular causes of the changes which bodies undergo are covered by [the] third laws-or at least the law covers all the changes which are themselves corporeal" (AT VIIIA 65; CSM I: 242). Della Rocca argues this passage should in fact be translated so it finishes "all the particular causes of changes which are themselves corporeal," and since Descartes is clearly presupposing that there are such changes, this strongly supports BODIES ((1999): 53). But even using the CSM translation, the passage seems to be to be endorsing not just that bodies change but that bodily changes are produced by other bodies. So long as some of these changes are changes in movement, BODIES is true. And the contents of the laws themselves spell out that bodies move bodies: they halt them, deflect them, rebound off them. When he glosses the laws to Clerselier in a 1645 letter, there is no mention of God (AT IV 183-188; CSMK: 248). When he proves the first part of the third law of motion, Descartes writes, "If one body collides with a 12 Della Rocca argues that close textual analysis of the Principles, especially II.37, II.40, II. 43, II.45, and III.56, supports BODIES even more strongly than I have suggested here. See Della Rocca (1999), especially pp. 52-62. Della Rocca (2007) summarizes the argument. Platt (2011b) comes to the same conclusion- that the passages from the Principles that supposedly tell against BODIES in fact support it-but takes a different path to it. In The World, Descartes lays out laws of motion that also seem to me to imply that bodies move bodies (AT XI 37-46; CSM I: 92-97). Machamer and McGuire accept that those laws do imply that bodies move bodies. They differ from me when they claim that Descartes's changed his view about whether bodies move bodies during the span from The World to The Principles. Engaging with Machamer and McGuire's extremely subtle argument would make this paper twice as long. The face-value reading of The Principles is endorsed in Cottingham (1997): 163. The similarity between Descartes's views on body-body causation in The World and The Principles is endorsed in Platt (2011b): 864. Ott notes that The World explicitly says that bodies are particular causes of motion in its second law and notes that the Principles does not. Ott puts this difference to work in his argument that Descartes is an occasionalist ((2009): 58). 16 second, hard body in its path which it is quite incapable of pushing..." It is very hard to resist that idea that Descartes believes some bodies are capable of pushing others. If so, BODIES is true. But significantly better scholars than I have resisted that Descartes holds that bodies can push other bodies. Consider this bit from Garber, One way or another Descartes holds that it is an immutable God whose divine sustenance is responsible for the various laws Descartes posits, for the conservation of quantity of motion, for the persistence of motion, for the orderly exchange of motion in collision. This suggests that the force Descartes appeals to in [the third law, namely imparted in collisions], and the tendency a body has in its state derive from God, from the immutable way in which he sustains the world he creates, in particular, from the way in which he sustains the bodies in motion in that world. In this way force is not in bodies themselves (Garber (1992a): 320). I agree with all of the first sentence. Descartes holds that, in some way or other, God- due to His simplicity and immutability-is responsible for the laws of nature and, because of this, responsible for the conservation of quantity of motion, etc. And I agree that if bodies move bodies, their power to do so derives in some way from God. What I disagree with is that it follows from this-or is even particularly good evidence-that bodies don't move bodies. To be clear, I have been arguing so far that the Principles-based case against BODIES is not particularly strong. As far as PARITY is concerned, that is neither here nor there. But what I have argued so far has the following upshot: A case just like the Principles-based case against BODIES can be made against MINDS. And, I think, that case against MINDS-just as PARITY predicts-is no stronger than the case against BODIES. My interpretation of Descartes's view of God's role in body-body causation can be adapted to resolve a tension in Descartes's views about the thesis that minds move 17 bodies. On the one hand, he clearly seems to hold that thesis and plainly asserts it in the correspondence with Elisabeth. On the other, he also writes to Elisabeth, All the reasons that prove that God...is the first and immutable cause of all effects that do not depend on human free will prove similarly, I think, that he is also the cause of all the effects that do so depend.... [G]od is the universal cause of everything in such a way as to be the total cause of everything... (AT IV 314; CSMK: 272)13 This looks to deny that minds move bodies because it looks to say God is the cause of all effects that (seem to) depend on our minds. If by "first cause," though, Descartes means what I think he means by "primary cause," there is no problem here. (AT uses the same expression "la cause premiere" in both this letter and Principles II.36.) I read this passage to Elisabeth as a reminder that what happens in the world goes according to God's plans, not a denial of mind-body causation. In fact, I believe Descartes is assuming that minds move bodies in the passage. Its first sentence claims that God is "the cause of all the effects that do depend [on human free will]." This assumes that there are effects of free will and, hence, with the plausible assumption that some effects of free will are bodily movements, it assumes the thesis that minds move bodies is true. This reading gets support from the 1645 letter in which Descartes insists to Elisabeth that mind-body causation is consistent with finite beings depending for their continued existence on God. Geoff Gorham reads these bits of the Elisabeth correspondence similarly: It is consistent with-and, in fact, endorses-that minds move bodies while also giving God an important causal role ((2004): 416-420). I differ from Gorham in holding that the Principles should be read in the same way: They are consistent with- 13 Clatterbaugh notes that this passage supports the claim that Descartes is an occasionalist ((1999): 41). For if the passage shows that there is no mind-body causation, it would also show that there is no mindmind causation (as when your present mental state produces some later one) or body-body causation. 18 and, in fact, endorse-that bodies move bodies while also giving God an important causal role.14 But the truly important thing for this part of my argument isn't the endorsement of bodies moving bodies or minds moving minds-that is important in §7-but, rather, the case for PARITY: In the Elisabeth correspondence, God is given a large role, a role that perhaps threatens to show minds don't move bodies just as, in the Principles, God is given a large role, a role that perhaps threatens to show bodies don't move bodies. This is what my argument for PARITY predicts: The case stemming from Descartes's metaphysics against the thesis that bodies move bodies is only as strong as the case against the thesis that minds move bodies. 6 I should be more cautious: The case stemming from God's role in Descartes's metaphysics is as strong against the thesis that bodies move bodies as against the thesis that minds move bodies. But there are other aspects to Descartes's metaphysics. Descartes thinks that the nature of body is merely being extended and that all the other intrinsic properties of bodies are modifications of extension. Being shaped like a square, for example, is a modification of extension. Being six feet tall, for example, is a modification of extension. If bodies move bodies, bodies have the power to move bodies. Let us assume is an intrinsic property (but see footnote 16 for a case against the 14 Relatedly, see Descartes's 1643 letter to Mersenne in which he claims that the laws of nature follow from God's perfection and also claims that bodies impel each other. See, too, Descartes's 1645 letter to the Marquess of Newcastle in which he asserts that God is the sole general cause of all things just after detailing several instances of body-body causation (AT IV 328; CSMK: 274-275). Ott reads the letter as supporting Descartes's occasionalism ((2009): 74), as supporting not just that BODIES is false but MINDS is, too. But that reading makes Descartes's letter bafflingly disjointed: He at first is asserting that bodies cause this and that and then, all of a sudden, is insisting that bodies cause nothing. I think occasionalist readings of the Elisabeth correspondence are similarly 19 assumption). So, if Descartes is right, it is a modification of extension. A case against BODIES now suggests itself: It is hard (impossible?) to see how something the nature of which is merely being extended can move a body. So Descartes thinks bodies cannot move bodies. So BODIES is false and Descartes denies that bodies move bodies. The argument is clearly invalid. From the premises that it is hard to see how an essentially merely extended thing moves bodies, nothing follows about Descartes's views. From the premise that Descartes found it hard to see how an essentially merely extended thing moves bodies you could build a better case that BODIES is false. Did Descartes find it hard to see how bodies move bodies? There is some reason to think not.15 In Principles IV.198, Descartes contrasts our inability to understand how bodies could have substantial forms or scholastic real qualities with our ability to understand how one body can move another. We understand very well how the different size, shape, and motion of the particles of one body can produce various local motions in another body. But there is no way of understanding how these same attributes (size, shape, and motion) can produce...substantial forms and the real quality which many philosophers suppose to inhere in things. (AT VIIIA 322; CSM I: 285) In other words, not only do bodies move bodies but we understand how they do so. What we don't understand is how bodies can have, say, the real quality of heaviness. This is some evidence that Descartes thought it was not mysterious how bodies move bodies. And nowhere that I know of does he puzzle over an essentially merely extended disjointed. 15 Gabbey (1980), Guerolt (1980), and Schmaltz (2007) defend at length that Descartes had an explanation of body-body causation with all three providing detailed accounts of force. Della Rocca (2000), Hattab (2007), Pessin (2003), and Platt (2011a and 2011b) defend this at length with detailed accounts of 20 thing having the power to move another extended thing. Compare that with an essentially merely extended thing being colored or having a form or thinking, all of which properties he explicitly denies that extended things have. For argument's sake, though, assume that Descartes did find it puzzling how bodies move bodies. Even if he did think there is such a mystery, however, there is no problem here for PARITY-If Descartes is committed to the thesis that minds move bodies, he is committed to the thesis that bodies move bodies To see there is no problem, consider the following: Descartes holds that the nature of minds is merely thinking. So all the intrinsic properties of minds are modifications of thinking. Having the power to move bodies is an intrinsic property of minds. So it is a modification of thinking. To see how something the nature of which is merely being a thinking thing can move bodies is hard (impossible?). If it were not hard to see how minds move bodies, then Descartes would have explained how it happens to all of the many people who asked him how it happens. So there is no problem for PARITY. If it is hard to see how bodies move bodies, it is hard to see how minds do. If unintelligibility considerations are evidence against body-body causation, so too are they evidence against mind-body causation.16 Descartes's metaphysics of body-body causation. 16 An objection to my claims here: It might be that the difficulty in seeing how minds move bodies is not evidence against mind-body causation since the power of mind to move bodies is a feature not of mind but, rather, of the mind-body union and we make no sense of the powers of the union. In the correspondence with Elisabeth, Descartes concedes that it is unintelligible how minds move bodies. This is, however, unsurprising to him since the notion of mind-body causation falls under the notion of the mind-body union: "we have...the notion of [the mind-body] union, on which depends our notion of the soul's power to move the body" (AT III 665; CSMK: 218), and the notion of the mind-body union is, if not unintelligible, then close to it (AT III 692; CSMK: 227). By contrast, the power of body to move bodies is a feature of body and such features, Descartes 21 Fair enough. But the previous objection to PARITY, though unpersuasive, is onto something. Minds are at least active things, whereas bodies are passive. So body-body causation is even less intelligible than mind-body causation-there is more of a case against the former than the latter. So there is a case against body-body causation that is not a case against mind-body causation. So one premise of my argument for PARITY is false. Slightly more explicitly, the argument goes: According to Descartes, bodies are essentially merely extended. Extension is passive. Causal power, by contrast, is active. How could something essentially merely extended, then, have causal power?17 Commentators have, largely, been unable to answer this question. Body, they say, is holds, "can...be known by the intellect alone, but much better by the intellect aided by the imagination" (AT III 691; CSMK: 227). So whereas we ought not expect it to be intelligible how minds move bodies, we ought to expect it to be intelligible how bodies move bodies. Since it is not intelligible how bodies move bodies, this is sufficient to reject that bodies do so. This might make for an objection to PARITY since the unintelligibility of body-body causation would be evidence against BODIES but the unintelligibility of mind-body causation would be no evidence against MINDS. This line of thought is mistaken. One response, as I have emphasized, is to deny that Descartes finds body-body causation unintelligible. Another response comes from the view defended by Della Rocca (1999), Clarke (2000), and Pessin (2003) according to which causal powers are extrinsic properties of bodies derived from the will of God. Unlike, say, shape, such properties needn't be explained entirely in terms of extension and, hence, the difficulty in doing so is no problem. A third response goes as follows: Descartes was in two minds about whether the mind's power to move bodies falls under the notion of the mind-body union. On the one hand, he says, in correspondence with Elisabeth and in Meditation Six, that it does. On the other, he says things implying it doesn't. For the minds of angels and God have the power to move bodies (see AT V 347; CSMK: 375; see Schmaltz (2007): 142 on disembodied mental causation). Theirs is simply a mental property, falling under the notion of mind, a notion that, unlike the notion of body, is best comprehended without help from the imagination (AT III 691; CSMK: 227). So Descartes seems to me to be leaving it open that the power to move bodies is a feature of mind and not (merely) the mind-body union. Doing so seems the more tenable position since it allows a human soul retains the power to move bodies after death; it just lacks a body to move. But, if mind's power to move bodies is a feature of mind rather than (merely) the union, and if it is hard to see how it has such a power, we shouldn't brush this difficulty off on account of it stemming from the mysterious mind-body union. 17 A question raised more or less pointedly by La Forge (I rely on Nadler (1998)), Le Grand (1694) (I rely on Clatterbaugh (1999)), Malebranche (1992), Hatfield (1977), Garber (1992), Simmons (2001), Schmaltz (2002), Machamer and McGuire (2009), and Hattab (2010). Cottingham (1997) notes-and I wholeheartedly agree with this-that though Descartes's commentators are quite skeptical of the idea that something that is essentially merely extended could move 22 passive. By contrast, "How could something essentially merely thoughtful have causal power?" is not a hard question. Thinking is an activity. From all this, the objection goes, there is a Cartesian case against body-body causation that is clearly not applicable to mind-body causation. Therefore, my argument for PARITY is unsound.18 But what is meant by "active" and "passive" here? The most straightforward way to understand the argument would be if all 'active' meant was 'having causal power' and all 'passive' meant were 'lacking causal power.' But then the argument against the thesis that bodies move bodies would be question-begging against those who hold that bodies move bodies and, hence, have causal power. Furthermore, the argument relies on the idea that the mind's activity makes answering the question, "How do minds move bodies?" easier to answer than, "How do bodies move bodies?" I think that's a mistake. For in trying to make sense of how minds move bodies, the issue is not whether minds can be active. The issue is whether we can make sense of the idea that minds engage in a certain activity, moving bodies. An example can make this point. Say that my mind has a certain causal power-it produces inferences-that we can make perfect sense of. Say that we now discover that my mind can also bend spoons from a distance. How it can do this would be completely baffling. Noting that my mind is an active thing, I think, would not make seeing how my mind can bend spoons any less baffling. What is wanted is an explanation for how minds engage in a certain activity; noting that they engage in some other activity doesn't provide help to provide one. And insisting that activity is a necessary condition for being able to move a body and, further, that minds meet that condition, bodies don't just begs the question something else that is merely extended, there is little evidence that Descartes himself thought this (164). 23 against proponents of BODIES. Descartes had nothing helpful to say about how minds move bodies. He asserts, rightly, I think, that minds do move bodies and so it seems that MINDS is true. If things are as they seem and MINDS is true and Descartes thinks it is mysterious how minds move bodies, then it cannot be sufficient reason to deny BODIES that Descartes thinks it is mysterious how bodies move bodies. Again, the cases against BODIES and MINDS are equally powerful. Hence, Descartes can hold that having the power to move bodies is a modification of extension and he can hold that it is a modification of thinking and, in both cases, we do not understand how this can be. No one, by contrast, wonders how being square can be a modification of extension or the property of drawing an inference can be a modification of thinking. The power to move a body, unlike the properties being square or drawing an inference, is a brute modification of extension and thinking, one where we do not understand how the one property is a modification of the other. Now there is a problem. I believe there is a very strong case for BODIES and also a case-less strong but not negligible-that the power to move bodies would be a brute modification of extension.19 Say that he thinks the power to move bodies is a brute modification of extension. Why allow just that one brute modification? Why not say that being a thinking thing is a brute modification of being extended? Why not say that being yellow is a brute modification of being extended? Or that heaviness is a brute modification of it? Descartes does not say any of these things. He has good reason for 18 Cf. Platt (2011b): 850-852 which formulates the argument and compellingly replies. 19 Clatterbaugh makes a case for ascribing a belief in brute causal powers to Descartes though he stops short of endorsing it ((1999): 42). Cf. Clarke (2006): 269. 24 not saying them, but what he says instead-minds are immaterial, no bodies are colored, there is no real quality of heaviness-leads to mystery. At any rate, whether or not Descartes thinks the power to move bodies is a brute modification of extension, if he accepts that minds move bodies, he at least accepts that the power to move bodies is a brute modification of thought. Otherwise, when Elizabeth or More or whomever asked how mind can move body, he would have explained. So, if MINDS is true, there is at least one brute modification. This is a problem for Descartes. BODIES doesn't make it worse.20 The argument of this section has been byzantine so it is worth summarizing it here at the end. I considered a final objection to my argument for PARITY-If Descartes is committed to the thesis that minds move bodies, he is committed to the thesis that bodies move bodies That argument included this premise: The sort of evidence Descartes has telling against the thesis that bodies move bodies tells against the thesis that minds move bodies. The objection to this premise goes: It is hard to see how essentially merely extended things move bodies. It is not hard to see how essentially merely thinking things move bodies. Hence, 20 Does it make it better? Descartes could accept brute modifications having to do with causal powers- and only causal powers-in general. The limits of our conceptual powers when it comes to understanding causation are flagged in the conversation with Burman (AT V 163; CSMK: 346). This bit of correspondence is important for two additional reasons: When Descartes says "it is very difficult to explain" how minds move bodies, this is an evasive way of saying he has no idea. (He'd have said so otherwise.) So he is denying the validity of this implication: It is hard to see why X. Hence, X isn't the case. To boot, he explicitly accepts that bodies have effects on minds. So, if the claim that bodies are "passive" includes the claim that bodies lack causal powers, Descartes is rejecting that claim. (He does so, too, in the Meditations.) 25 Descartes has a sort of evidence against body-body causation-evidence from unintelligibility-that isn't evidence against mind-body causation. Hence, It's not true that the sort of evidence Descartes has telling against the thesis that bodies move bodies tells against the thesis that minds move bodies. This objection is obviously hopeless. It's invalid: From what is hard to see-hard for us or in general-nothing follows about the evidence Descartes has. He might not have found it hard to see how essentially merely extended things move bodies and, in fact, there is evidence that that is the case. Also, the second premise is quite obviously not true: For Descartes, for me, for Descartes's correspondents, in general, it is hard to see how essentially merely thinking things move bodies. Nevertheless, the objection is on to something important, something like: It is harder for Descartes to see how bodies move bodies than to see how minds do. Hence, Descartes has a sort of evidence against body-body causation that isn't evidence against mind-body causation. Hence, It's not true that the sort of evidence Descartes has telling against the thesis that bodies move bodies tells against the thesis that minds move bodies. And the case for the first premise here is something like: Bodies are inert. Minds are active. Since activity is a necessary condition for moving a body, it is at least in that way easier to see how minds move bodies than bodies do.21 First, again, the evidence in 21 Even if in one way it is easier to see how minds move bodies, there might be other ways that make it easier to see how bodies move bodies. And in some ways it is easier. Reiterating something that came up in §1, I have been defending not just that bodies have causal powers and not just that they have effects on other bodies and not just that these effects include moving other bodies. I have been defending that Descartes allows bodies to initiate motion. All that is needed to defend the thesis that bodies move bodies is an instance of a body moving another. Such an instance needn't involve initiating motion. It could simply be deflecting, blocking, glancing, and so on. These instances of body-body causation seem much easier to explain in terms of extension, than, say starting the chain of motion in the first place. But if bodies deflect bodies, then that bodies move bodies is true. Is it really so hard to see how something 26 support of the alleged difficulty is not typically from considerations about what was hard for Descartes to see. Second, most importantly, the objection-the italicized "inert," really-begs the question against those who endorse BODIES. What they hold is precisely that Descartes holds that bodies aren't inert insofar as that claim just amounts to bodies not have causal power. Merely extended? Of course. But that, they hold, is compatible with being able to move other bodies about. 7 Those who ascribe occasionalism to Descartes can accept PARITY. They can then reject BODIES-He is committed to the thesis that bodies move bodies, and, hence, reject MINDS-Descartes is committed to the thesis that minds move bodies. Indeed, part of my case for PARITY might seem to support occasionalism since I have drawn attention to several aspects of Descartes's case for minds moving bodies and against bodies moving bodies that make the thesis that minds move bodies fit uncomfortably in Descartes's system. And there is a powerful consideration I have left out: Descartes believes that the world persists because God continually preserves it. It is unclear how the preservation works, but one idea is that God constantly recreates the world, constantly making anew my body, mind, computer keyboard, and each of yours, and so on. An argument against the thesis that bodies move bodies now suggests itself. The argument has been discussed extended could deflect something else? (There is an issue about solidity here, but in the debate about Descartes and BODIES that issue is typically left to the side.) 27 in detail in many places.22 If the world is constantly being recreated, then "motion" is really just God (re)creating bodies in different places at different times. Take what seems to be a billiard ball pushing another billiard ball. At t1, the first approaches the second. At t2, they collide, the first seeming to push the second. At t3, they veer off. What is really going on is that, at t1, God creates the first ball at p1 and the second at p2. At t2, he creates both at p2. At t3, he creates the first at p3, the second at p4. And so on. Inasmuch as this is motion at all, it is caused only by God. Hence, bodies do not move bodies. Hence, if Descartes goes for the divine recreation theory of divine preservation, then, so long as he saw its implications for causation, BODIES is false. Whether Descartes holds the divine recreation theory is controversial,23 but let us assume that he does. If so, the claim that the motion of the billiard balls is caused only by God comes from the claim that all motion is caused by God because all motion is really just God (re)creating bodies in different places at different times. From that premise, though, it follows that minds don't move bodies. Each putative case of a human mind moving a body is really just a case of God creating a mind in some state and then creating a body in some state. For example, at t1, God creates a mind willing an arm to rise. At t2, he creates the arm rising. Insofar as this is motion at all, it is caused only by God. So if the argument shows that bodies fail to move bodies, it equally well shows that minds fail to do so, too. It tells equally against the two views and so obviously that it is incredible that Descartes could have 22 See, among others, La Forge's views (reported in Nadler (1998)), Kemp Smith (1953), Hatfield (1977), Garber (1987), Garber (1992a) and (1992b), Bennett (2001), Gorham (2004), Machamer and McGuire (2009), and Ott (2009). Kemp Smith, La Forge, and Ott, at least, think the argument leads to occasionalism. 23 Garber (1992a) explains and assesses the controversy. 28 missed it. This is further support for PARITY and, in particular, the premise in the argument for it according to which the sort of evidence that tells against the thesis that bodies move bodies tells against the thesis that minds move bodies. Those who think Descartes goes for occasionalism think Descartes endorses the argument, sees it tells against mind-body and body-body causation, and, hence, hold that MINDS and BODIES are false. Having established PARITY and ignoring the possibility that BODIES is true but MINDS is false, I prefer MINDS and BODIES to neither BODIES nor MINDS just because the texts are overwhelmingly supportive of the former, I think. This is evidence that Descartes's system makes room for both. Just as Descartes says many times and very clearly that minds move bodies, he says many times and very clearly that bodies move bodies. He says throughout his scientific work but also in passages from metaphysical work and correspondence on causation.24 I think the best explanation of this is that Descartes saw that his system implies that bodies move bodies and, hence, commits to that thesis. Some of the texts endorsing or implying that bodies move bodies-selections from the Principles, the Meditations, and the correspondence-have been mentioned. There are more. In correspondence with More, Descartes, immediately after claiming that 24 Margaret Wilson and John Cottingham take Descartes's repeated assertions that bodies move bodies at face value and, hence, go for BODIES. See Wilson (1999): 68, fn. 70 and Cottingham (1997): 160, 161-162. Compare with Rozemond (1999) on whether Descartes believes that bodies have mental effects. Rozemond cogently argues that Descartes's claims that they do should be taken at face value and not reconstrued as loose talk. "Descartes's use of causal language could perhaps be dismissed if he ever denied that the body serves as a cause in sensation (or that it served as a cause under any circumstance). After all, Malebranche spoke of occasional causes in the created world but he argues that the creation has no genuine causal powers. But Descartes never does anything of the sort" (459). Neither does he in the body-body 29 everything about bodies can be explained mechanically, holds that it is no disgrace to think that immaterial minds move bodies. What he is getting at is that we understand how bodies move bodies, and, though we don't understand how minds do it, we can be confident that they do, too (AT V 344 and 347; CSMK: 374-375).25 Writing to More, Descartes explains the movements of animals by positing animal spirits that force the bodies of animals about. This contrasts, Descartes thinks, with our own movements which are caused not entirely by spirits-by bodies-but partly by our minds (AT V 276; CSMK: 365).26 The passage exemplifies a type of maneuver Descartes uses elsewhere. He frequently endorses that minds move bodies while at the same time endorsing that bodies do so. The thrust is that just as bodies move bodies, so, too, do minds do so. He does so more than once to More. Not only in the above passage but also when he claims that some motions of our limbs "are caused not by the soul but simply by the machinery of the body" (AT V 344; CSMK: 374).27 case. The texts against BODIES aren't explicit denials of the thesis that bodies move bodies. 25 More himself may have rejected BODIES. In "Responsio ad Fragmentum Cartesii," he asserts that Descartes's view is that "there is some external power, whether from God or from some incorporeal substance created by God, whereby matter is aroused into motion" (AT V 646-647; my emphasis). That the only external forces More singles out are immaterial suggests he denies BODIES. Gabbey (1982) is a dazzling account of More's views on Descartes. 26 Descartes writes, "Since we believe there is a single principle within us that causes these movements- namely, the soul...-we do not doubt that such a soul can be found in animals. I came to realize, however, that there are two different principles causing our movements. The first is purely mechanical and corporeal, and depends solely on the force of the spirits and the structure of the organs, and can be called the corporeal soul. The other, an incorporeal principle, is the mind..." (AT V 276; CSMK: 365) 27 These passages from the More correspondence are important, I think, because they counterbalance another passage in that correspondence that supports the denial of BODIES. Descartes writes, explaining the movement of bodies, "[a body] receives an impulse from God" (AT V 404; CSMK: 381) and then singles out other things that can impel bodies-our minds and unnamed other causes, probably angels-but doesn't single out bodies. (This is the only passage I know of in the correspondence that provides evidence that Descartes holds that God shoves matter around (cf. Cottingham (1997)).) About this passage, Garber writes, "If Descartes really thought bodies could be causes of motion like God, us, and probably angels, I suspect he would have included them explicitly in the answer to More; if bodies could be genuine causes of motion, this would be too important a fact to pass unnoticed" (Garber (1992b): 321). 30 So, too, he tells Gibieuf that animal bodies cause in animals what imagination causes in us (AT III 479-480; CSMK: 203-204). He tells Hyperaspistes that, just as bodies affect our brain, so, too, do our minds (AT III 424-425; CSMK: 190). In the Description of the Human Body, Descartes's purpose is to "enable us to know distinctly what there is in each of our actions which depends only on the body and what there is which depends on the soul" (AT II 227; CSM I: 316). The dependence here is causal dependence, and Descartes is clearly assuming that some actions depend on the body, some on the mind. If PARITY is false and Descartes holds that minds move bodies but bodies don't, the above are somewhat bizarre passages since Descartes truly means that minds move bodies but is speaking loosely when he says that bodies move bodies. Also, they are trouble for the occasionalist interpretation of Descartes since endorsing occasionalism would be a satisfactory response to some of the worries Descartes is responding to. But in none of these letters does he endorse it. Finally, Descartes writes that Elizabeth falls into error by trying "to conceive the way in which the soul moves the body by conceiving the way in which one body is moved by another" (AT III 666; CSMK: 218). A few lines later, he complains that "We have hitherto confused the notion of the soul's power to act on the body with the power Unsurprisingly, my view is that the failure to single out bodies as movers of bodies is not particularly important. I think Descartes is taking that bodies move bodies for granted since the rest of the correspondence has established it. Even several lines later, I think, Descartes does mention that bodies can be genuine causes of motion since he reminds More that "force is applied [to bodies] at different times to different parts of matter in accordance with the laws set out in [Principles II]" (AT V 405; CSMK: 382). Since I think those laws endorse that bodies move bodies, I think Descartes is singling out bodies as causes here. Of course, since Garber reads the Principles differently, this won't persuade him. 31 one body has to act on another" (AT III 667; CSMK: 219). If BODIES is false, these quotations are extremely misleading since the first presupposes that there is some way in which one body moves another, the second that bodies have power to act on one another. When Elisabeth asks Descartes how minds or an incorporeal God move bodies, he does not question her presupposition that bodies can move bodies.28 Garber argues that Descartes made a mistake in not doing so (Garber (1983): 186-188). That Descartes didn't say what Garber thinks he ought to have said seems to me to be evidence that BODIES is true. Further evidence against Garber's interpretation is that the mistake Garber thinks Descartes makes here is one he also makes with More. He responds to More's question about how an incorporeal substance can move a body (AT V 404-405; CSMK: 381-382). More implies that he understands how bodies can move bodies. The stress in his question is on how an incorporeal thing can move a corporeal thing. If More thought he did not understand how bodies move bodies, his question would just have been: how does anything move a body? That is not what More asks, though, and to his actual question Descartes just insists that incorporeal things can move bodies. This is some support for BODIES. If Descartes denies that bodies move bodies, this response to More is misleading and needlessly weak. He should point out that More has a false presupposition, namely, that there is no problem understanding how bodies move bodies, and, thus, More's position is just as mysterious as that an incorporeal mind moves a body. And note that the response Descartes gives Elisabeth seems to be one he is reasonably happy with. At least, in a 1641 letter to Hyperaspistes, Descartes says that 32 immaterial minds, like material bodies, move bodies, just as he says this in his later correspondence with Elisabeth. He then, in the letter to Hyperaspistes, uses the same imagery to make mind-body causation acceptable that he uses with Elisabeth (AT III 424-425 and 434; CSMK: 190 and 197). In sum, Descartes's texts-largely, almost wholly-support BODIES.29 Unlike Malebranche on causation, there is almost no evidence that Descartes's repeated assertions of the claim that bodies move bodies or of theses that imply it are not to be taken at face value. The only evidence I know of is the material from the Principles and the correspondence with Elisabeth, More, and Regius flagged above. Again, the point isn't that Descartes's talk of bodies moving bodies guarantees BODIES. Malebranche clearly denies that bodies move bodies while also going in for much talk of bodies moving bodies. However, Malebranche clearly denies that bodies move bodies. Descartes never does.30 Moreover, while those who hold that Descartes is an occasionalist are in position to argue that Descartes's causal talk is not to be taken at face value, those who hold MINDS, reject PARITY, and deny BODIES should be wary of doing so. Doing so leaves them open to the charge that the textual evidence in favor of MINDS is misleading. 8 28 See the letters of May 21, 1643 (AT III 665; CSMK: 218) and June 28, 1643 (AT III 691-694; CSMK: 227-228). 29 Besides the Principles passages and letters to More quoted earlier, I believe the best textual evidence that BODIES is false is a 1641 letter to Regius in which Descartes claims, "Length, breadth, and depth, and the power of receiving all kinds of shapes and motions cannot be taken from matter...any more than thought can be taken from mind" (AT III 455; CSMK: 199; my emphasis). The lack of the assertion that bodies have the power to produce motion is, when set next to the assertion that they have the power to be moved, quite striking. 33 My argument for BODIES-Descartes is committed to the thesis that bodies move bodies differs from others'. Unlike Della Rocca's, it involves no close textual analyses to reveal Descartes's support for the thesis that bodies move bodies. Unlike Gabbey's and Gueroult's, it involves no physical explanation of force. Unlike Hattab's, Pessin's, Platt's, and Schmaltz's, it involves no spelling out of the metaphysics of causation. Rather, the argument is that MINDS-Descartes is committed to the thesis that minds move bodies stands and falls with BODIES, and, since MINDS stands, so does BODIES. The reasons Descartes has to deny that bodies move bodies-stemming from the unintelligibility of body-body causation or its badness of fit with the rest of his metaphysics-are equally reasons to deny that minds move bodies. The sort of reason he has to hold that minds move bodies-stemming from sense perception and from the senses' importance in protecting the mind-body union-equally support that bodies move bodies. The argument asserts PARITY-If Descartes is committed to the thesis that minds move bodies, he is committed to the thesis that bodies move bodies. If that premise is true, the standard view according to which MINDS is true, Bodies isn't is false and unstable. If it is true, it might be useful to those who see Descartes as an occasionalist. They could use it to show that the reasonably common view that BODIES is false proves the very uncommon view that MINDS is false, too. My argument, by contrast, uses MINDS and PARITY to prove BODIES. The 30 Cottingham (1997), Della Rocca (1999), and Platt (2011b) emphasize this. 34 argument for MINDS came from Descartes's repeated claims that the senses establish that minds move bodies. Some might think sense evidence is not, by Descartes's own lights, good evidence, but Descartes so clearly holds that minds move bodies, I think, that he must think it is good evidence for the thesis that minds move bodies. The senses have some role to play in justifying causal beliefs. They justify that minds and bodies move bodies, for example. What enables them to play this role without being able to justify various other metaphysical claims? Which other claims can they justify? I sketched the start of an answer: The senses are designed to protect the mind-body union and perceiving body-body and mind-body causation, Descartes thinks, is crucial to doing so. Finally, whether or not my argument for it is sound, if BODIES is true, that is an important result. It would cast doubt on the soundness of this familiar line of thought: Descartes holds bodies are essentially merely extended. Hence, He holds they are inert. Hence, He holds that they move no bodies. If BODIES is true, the conclusion is false. At least one of the inferences is invalid, I think. Also, if BODIES is true, it might be that the power of bodies to move bodies is a brute power, a feature of bodies that is a modification of extension but one which we can't understand. There is evidence that this isn't the case. As I noted, in the Principles, Descartes boasts that it is easy enough to explain how bodies move bodies. And there is no explicit statement of the bruteness of body-body causation. Nevertheless, many commentators have had terrible trouble seeing how to explain how an essentially merely extended thing might move another thing. But they have had trouble, too, seeing how an unextended thing might move an extended thing, and, I believe, Descartes quite clearly believes unextended things do 35 move extended things. So MINDS and BODIES raise fundamental questions about Descartes's metaphysics and epistemology. Our inability to understand how something could be the case is sometimes sufficient, Descartes believes, to reject that that thing is the case. It is sufficient, Descartes believes, to reject that there are various real qualities. But clearly the unintelligibility of a merely thinking thing moving a body is insufficient to reject that such things do move bodies. Why not? More generally, when it comes to moving bodies there are limits on what we can explain. Why any limit? Where are these limits, exactly? Why there? One possibility is that the power to move is a power of the mind-body union and, generally, Descartes thinks that certain features of the union are unintelligible to us. But this is both a mistake-the power is a power of minds rather than the union-and a copout-it wishes away a problem Descartes should deal with. He might deal with the problem by claiming that causal powers in general are brute features of whichever things have those powers. If so, the limits of rationalism are not drawn at the mind-body border but, rather, wherever a mind or body meets another.31 31 There is a connection here with Descartes's views on personal identity. If Descartes holds what Wilson calls the "natural institution theory" of personal identity, the union of the mind and body just is the causal interaction between them (Wilson (1978)). If so, the bafflingness of certain powers and the bafflingness of the mind-body union are quite closely connected. 36 REFERENCES AT: Adam, Charles and Paul Tannery, ed.s. 1964-1976. Oeuvres de Descartes. Paris: C.N.R.S. CSM I: Cottingham, John, Rupert Stoothoff, and Dugald Murdoch, ed.s. 1985. The Philosophical Writings of Descartes, Volume One. Cambridge: Cambridge University Press. CSM II: Cottingham, John, Rupert Stoothoff, and Dugald Murdoch, ed.s. 1985. The Philosophical Writings of Descartes, Volume Two. Cambridge: Cambridge University Press. CSMK: Cottingham, John, Rupert Stoothoff, Dugald Murdoch, and Anthony Kenny, ed.s. 1991. The Philosophical Writings of Descartes, Volume Three. Cambridge: Cambridge University Press. Bennett, Jonathan. 2000. Learning From Six Philosophers, Volume One. Oxford: Oxford University Press. Broughton, Janet and John Carriero, ed.s. 2007. A Companion to Descartes. Boston: Blackwell Publishing. Clarke, Desmond. 2000. "Causal Powers and Occasionalism from Descartes to Malebranche" in Gaukroger, et al. (2000). Clarke, Desmond. 2006. Descartes. Cambridge: Cambridge University Press. Cottingham, John, ed. 1992. Cambridge Companion to Descartes. Cambridge: Cambridge University Press. Cottingham, John. 1997. "Force, Motion, and Causality: More's Critique of Descartes" 37 in Rogers, et al. (1997). Cottingham, John, ed. 1998. Descartes. Oxford: Oxford University Press. Della Rocca, Michael. 1999. "'When A Body Meets A Body'" in Gennaro and Huenemann (1999). Della Rocca, Michael. 2007. "Causation Without Intelligibility and Causation Without God in Descartes" in Broughton and Carriero (2007). Gabbey, Alan. 1980. "Force and Inertia in the Seventeenth Century: Descartes and Newton" in Gaukroger (1980). Gabbey, Alan. 1982. "Philosophia Cartesiana Triumphata" in Lennon, et al (1982). Garber, Daniel. 1983. "Understanding Interaction: What Descartes Should Have Told Elizabeth," reprinted in Garber (2001). Garber, Daniel. 1987. "How God Causes Motion: Descartes, Divine Sustenance, and Occasionalism," reprinted in Garber (2001). Garber, Daniel. 1992a. Descartes' Metaphysical Physics. Chicago: University of Chicago Press. Garber, Daniel. 1992b. "Descartes's Physics" in Cottingham (1992). Garber, Daniel. 1993. "Descartes and Occasionalism," reprinted in Garber (2001). Garber, Daniel. 2001. Descartes Embodied. Cambridge: Cambridge University Press. Gaukroger, Stephen, ed. 1980. Descartes: Philosophy, Mathematics and Physics. Towota, NJ: Barnes and Noble Books. Gaukroger, Stephen, Schuster, John, and Sutton, John, ed.s. 2000. Descartes' Natural Philosophy. New York: Routledge. Gennaro, Rocco and Charles Huenemann, ed.s. 1999. New Essays on the Rationalists. 38 Oxford: Oxford University Press. Gorham, Geoffrey. 2004. "Cartesian Causation: Continuous, Instantaneous, Overdetermined," Journal of the History of Philosophy 42: 389-423. Gueroult, Martial. 1980. "The Metaphysics and Physics of Force in Descartes" in Gaukroger (1980). Hatfield, Gary. 1979. "Force (God) in Descartes' Physics," reprinted in Cottingham (1998). Hattab, Helen. 2007. "Concurrence or Divergence? Reconciling Descartes's Science with his Metaphysics," Journal of the History of Philosophy 45: 49-78. Hattab, Helen. 2010. Review of Machamer and McGuire (2009), Notre Dame Philosophical Reviews. Hoffman, Paul, Owen, David, Yaffe, Gideon, ed.s. 2008. Contemporary Perspectives on Early Modern Philosophy: Essays in Honor of Vere Chappell. Peterborough, ON: Broadview Press. Kemp Smith, Norman. 1953. New Studies in the Philosophy of Descartes. New York: Russell and Russell. LeGrand, Anthony. 1694. An Entire Body of Philosophy. London: Samuel Roycroft. Lennon, Thomas, Nicholas, John, and Davis, John, ed.s. 1982. Problems of Cartesianism. Montreal: McGill-Queens. Machamer, Peter and McGuire, J.E. 2009. Descartes's Changing Mind. Princeton: Princeton University Press. Malebranche, Nicolas. 1992. Philosophical Selections. Indianapolis: Hackett. Nadler, Steven. 1998. "Louis de la Forge and the Development of Occasionalism: 39 Continuous Creation and the Activity of the Soul," The Journal of the History of Philosophy 36: 215-231. Ott, Walter. 2009. Causation and the Laws of Nature in Early Modern Philosophy. New York: Oxford University Press. Pessin, Andrew. 2003. "Descartes's Nomic Concurrentism: Finite Causation and Divine Concurrence," Journal of the History of Philosophy 41: 25-49. Platt, Andrew. 2011a. "Divine Activity and Motive Power in Descartes's Physics: Part One," British Journal for the History of Philosophy 19: 623-646. Platt, Andrew. 2011b. "Divine Activity and Motive Power in Descartes's Physics: Part Two," British Journal for the History of Philosophy 19: 849-871. Rogers, G.A.J., Vienne, J.M., and Zarka, Y.C., ed.s. 1997. The Cambridge Platonists in Philosophical Context. Dordrecht: Kluwer. Rozemond, Marleen. 1999. "Descartes on Mind-Body Interaction: What is the Problem?," Journal of the History of Philosophy 37: 435-467. Secada, Jorge. 2000. Cartesian Metaphysics. Cambridge: Cambridge University Press. Schmaltz, Tad. 2002. Radical Cartesianism. Cambridge: Cambridge University Press. Schmaltz, Tad. 2007. Descartes on Causation. Oxford: Oxford University Press. Simmons, Alison. 1999. "Are Cartesian Sensations Representational?," Nous 33: 347369. Simmons, Alison. 2001. "Sensible Ends: Latent Teleology in Descartes' Account of Sensation," Journal of the History of Philosophy 39: 49-75. Simmons, Alison. 2008. "Guarding the Body" in Hoffman, et al. (2008). Wilson, Margaret. 1978. Descartes. New York: Routledge. 40 Wilson, Margaret. 1999. Ideas and Mechanism. Princeton: Princeton University Press.