Part Two Philosophy of Mind 9781350067301_txt_prf.indd 179 21-08-2018 11:42:33 9781350067301_txt_prf.indd 180 21-08-2018 11:42:33 6 Spinoza’s Two Claims about the Mind-Body Relation Alison Peterman Introduction How is a particular mind related to its body?1 There are many ways to understand this question, and many different answers for those different ways. Spinoza makes a number of claims about this relationship, all of which are independently interesting. But it is not clear that they are compatible. In this chapter, I would like to focus on two of those claims, and to argue that although Spinoza sometimes run these two claims together, in fact he does not succeed in making them compatible with one another. I suggest that the illusion that they are compatible comes from an equivocation between two ways of using the phrase “insofar as” [quatenus], and that this type of equivocation runs deep in Spinoza’s metaphysics. Those two claims are: (1) Parallelism: the mind is causally and structurally linked to other minds in the same way that its body is linked to other bodies; (2) Idea-of: the mind is the idea of its body; or, the body is the object [objectum] of its mind. In focusing on these two, I will ignore some of those other interesting things that Spinoza writes about the mind-body relationship. For example, I will for the most part ignore his account of it in the earlier Short Treatise, where he claims that love constitutes the union of the mind with the body.2 But I will also ignore another of Spinoza’s commitments that might look more relevant: that the mind and the body are “one and the same thing, understood in two different ways” (E2p7s). There is a lot that is interesting about this claim, but I think it is fair to 9781350067301_txt_prf.indd 181 21-08-2018 11:42:33 182 Spinoza in 21st-Century American and French Philosophy put it aside in thinking through the relationship between Parallelism and Idea- of.3 Here is a condensed argument for why. Either Spinoza’s dictum that the mind and the body are “one and the same thing” amounts to the claim that the mind and the body are numerically identical,4 or it does not. If it does not, then we will have to interpret it in light of Spinoza’s other commitments about the mind-body relationship. But then it can’t really be used to understand those commitments. If it does amount to the claim that the mind and the body are numerically identical, then although it delivers to us an interesting ontological fact, that fact does not tell us anything more about the metaphysical, causal or explanatory relationship between the mind and the body. Presumably a very important part of what we want to know when we ask how the mind relates to the body is an understanding of the properties and functions of the mind and the body, and of how the properties and functions of one relate to the properties and functions of the other. But if Spinoza thinks that the mind and body are identical, then he denies the indiscernibility of identicals for many of the properties and functions you might be interested in knowing about. For example, just because a body is in a certain place or has a certain speed does not mean that the mind that is identical to it does, and just because the mind can represent bodies doesn’t mean that the body that is identical to it can. And indeed, Spinoza never really uses the claim that the mind and the body are one and the same thing to explain anything about the mind and the body—with one exception, which I will mention later. In what follows, I’ll outline Spinoza’s justifications for these two claims about the relationship between the mind and the body, Parallelism and Idea-of, and show that the arguments are entirely independent of one another. Then I’ll consider how Spinoza tries to connect them, show that he does not succeed, and draw a few lessons from that. In the next section, I will make a few preliminary comments about E2p7 and its scholium, and about E1a4, which Spinoza claims entails E2p7. In Section II, I will outline the argument for Parallelism, and in Section III, I will outline the argument for Idea-of. Section IV shows that there is some precedent in Descartes for distinguishing between two approaches to discovering the mind- body connection. I. E2p7 and E1a4 E2p7 and the accompanying demonstration, corollary and scholium are integral to understanding both Parallelism and Idea-of. 9781350067301_txt_prf.indd 182 21-08-2018 11:42:33 Spinoza and the Mind-Body Relation 183 The order and connection of ideas is the same as the order and connection of things. [E2p7] This is clear from 1a4. For the idea of each thing caused depends on the knowledge of the cause of which it is the effect. [E2p7d] The thinking substance and the extended substance are one and the same substance, which is not comprehended under this attribute, now under that. So also a mode of extension and the idea of that mode are one and the same thing, but expressed in two ways […] For example, a circle existing in nature and the idea of the existing circle […] are one and the same thing, which is explained through different attributes. Therefore, whether we conceive nature under the attribute of Extension, or under the attribute of Thought, or under any other attribute, we shall find one and the same order, or one and the same connection of causes, i.e. that the same things follow one another. [E2p7s] Yitzhak Melamed has, I think convincingly, shown that E2p7 and the italicized portion of E2p7s are different claims and that Spinoza relies on them in different contexts. E2p7—what Melamed calls “Ideas-Things Parallelism”—tells us something special about ideas and about their relationships with their objects. Meanwhile, E2p7s—what Melamed calls “Inter-Attributes Parallelism”—tells us about modes of different attributes in general: a mode of any attribute has the same causal and structural connections with the other modes of its attribute as its “parallel” mode does with the other modes of its attribute. This is true for all modes of all the attributes—not just extension and thought—and it tells us nothing about the relation between an idea and its object [objectum], or what it is the idea of.5 I agree that these are distinct, but I think that Spinoza runs them together a bit more than Melamed allows. For example, Melamed claims that Spinoza only thinks that parallel modes in different attributes are one and the same thing, but not that an idea and its object are one and the same thing.6 In contrast, I think that Spinoza does imply, at E2p7s, that an idea and its object are one and the same thing. He writes that “a mode of extension and the idea of that mode are one and the same thing” and that the Hebrews saw this when they “maintained that God, God’s intellect, and the things understood by him are one and the same.” And Spinoza seems to be using these considerations to motivate a slide from one to the other. In preparation for considering their uses in the proofs of Parallelism and Idea-of, I’d like to consider here how Spinoza justifies E2p7 and E2p7s. E2p7 is, notoriously, laconically proven from E1a4: This is clear from 1a4. For the idea of each thing caused depends on the knowledge of the cause of which it is the effect. [E2p7d] 9781350067301_txt_prf.indd 183 21-08-2018 11:42:33 184 Spinoza in 21st-Century American and French Philosophy E1a4 is doubtless one of the most fundamental commitments of Spinoza’s metaphysics: The knowledge [cognitio] of an effect depends on, and involves, the knowledge of its cause. [E1a4] Taking these together and focusing on involvement for simplicity’s sake, these suggest that Spinoza holds the following: Involves: The idea of an effect involves the idea of its cause. The meaning of Involves depends, of course, on the meaning of “involves” [involvere]. I cannot give a complete treatment of Spinoza’s use of involve here,7 but would just like to observe that there are two very natural ways of reading Involves.8 Let’s call the first one the mechanistic reading of Involves (InvolvesM). On InvolvesM, to say that the idea of A involves the idea of B is not to say much more than that the idea of B is at least a partial cause of the idea of A. E1a4 is used in this in the alternate demonstration of E2p5, where Spinoza is arguing that ideas can only be caused by other modes of thought; it is used similarly in the demonstration of E2p6. The second reading is the semantic reading of Involves (I’ll call it InvolvesS). On InvolvesS, to say that the idea of A involves the idea of B is to say that the content of the idea of A includes the content of the idea of B as a part. That Spinoza sometimes means Involves to have this sense is evident from certain applications of E1a4. For example, in the demonstration of E2p16, Spinoza cites E1a4 to show that the ideas of modes of affections of a given body “will necessarily involve the nature of each body [my italics].” The nature, not the idea, of each body.