Abstract
Leibniz believes that if there are corporeal substances, they have substantial forms, believes there are substantial forms, and believes there is a close connection between the first two claims. Why does he believe there is this close connection? This paper answers that question and draws out its bearing on the realism/idealism debate.
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Notes
Four texts stand out in support of Leibniz thinking there is a close connection between the two theses. See G II: 58/LA: 66 where Leibniz starts with DWW and ends up agreeing with SWR. See G II: 124/LA: 158–159 where Leibniz starts with DWW then says “when” not “if” you admit that there are forms, various theses follow. See, too, G II: 65–67/LA: 78–81 where Arnauld interprets Leibniz as holding DWW, but then asks a bunch of questions about SWR as if holding DWW commits you to SWR. Finally, see G II: 106/LA: 133 where Arnauld writes, “I have more to say about these…substantial forms which you think must be conceded to exist…because otherwise matter would not be a unity.” This sentence not only attributes a close connection to DWW and SWR but, also, endorses the realist view that Leibniz moves from DWW to SWR via the claim that there are bodies. Of course, the last two texts cited come from Arnauld, but Leibniz never challenges Arnauld on these points.
The ‘weak’/‘strong’ terminology comes from Daniel Garber. I use it slightly differently than he does. My taxonomy leaves out positions according to which some mind-like substances are not simple. The taxonomy also leaves open the relation between extension and force (on which see Garber 1985, 1992). The taxonomy also considerably simplifies idealism. For a much more nuanced account see Rutherford (2007). A second-last simplification: I ignore the possibility that Leibniz is, for some of the Arnauld correspondence, an external world skeptic. Of course, if he is an external world skeptic, he is not a realist—weak and strong realism commit to an extramental world—so skepticism is supportive of a main point of the paper. The role of external world skepticism in Leibniz’s skepticism about bodies is interesting but tangential to my arguments. For the purposes of this paper, I do not think the simplifications matter.
A last simplification is mentioned in footnote five.
I assume that Levey thinks the relevant bit of the Leibniz–Arnauld correspondence shows that Leibniz is a strong realist (see Levey (2003), pp. 245, 269, 270, 271 fn. 3). I argue the text implies neither strong nor weak realism.
A final simplification: I focus almost exclusively on Levey’s views as exemplars of the realist interpretation of Leibniz. Why?
Although there is a massive literature on realism versus idealism in the Arnauld correspondence and the issues are many, this paper focuses on one part of the wider issue: the connection between DWW and SWR. As far as I know, the argument that only realism can explain the connection was introduced by Levey and has never been discussed, though Sleigh (1990) hints at it. The main thesis of the paper is that there is an idealist-friendly, non-realist way of making the connection.
A subsidiary thesis of the paper is that the key passage Levey focuses on contains no commitment to realism, and is actually better interpreted in idealist-friendly, non-realist terms. The non-realist interpretation of the passage is just what you would expect, given the non-realist way of connecting DWW and SWR.
Of course, I cannot attempt here—cannot attempt anywhere—to resolve the realism/idealism dispute in general. But seeing how DWW connects to SWR sheds light on that debate, and on Leibniz’s criticisms of both of the Cartesian conception of mind and body. I believe it also sheds light on textual interpretation of Leibniz in C.D. Broad (1975), Daniel Garber (1985, 1992, 2005), Glenn Hartz (1992, 1998, 2007), and others.
Realism is bipartite: there are mind-like substances and bodies. Since it is common to realism and idealism that there are mind-like substances and, in the Leibniz–Arnauld correspondence their existence is in no doubt, in what follows I claim that establishing that there are bodies suffices for establishing realism.
“From [the two triangles argument] it follows that the substance of a body, if bodies have one, must be indivisible; whether it is called soul or form does not concern me” (G II: 72/LA: 88). Note that the two triangles passage, understood the way Levey understands it, is strongly supportive of strong realism rather than weak realism. By contrast, Levey’s other argument for realism is supportive of both strong and weak realism.
At least one brilliant scholar believes that Levey is right about Leibniz and realism and how Leibniz connects DWW to SWR. Arnauld repeatedly imputes realism to Leibniz in the correspondence and twice says that Leibniz connects DWW to SWR via realism. See G II: 85/LA: 106 and G II: 106/LA: 133. Also, in his 28 September 1686 letter, Arnauld raises seven questions about DWW, three of which presuppose that Leibniz hold realism.
Donald Baxter and Robert Sleigh would think Levey is wrong, but I agree with Levey that his interpretation of the two triangles argument is more faithful to the two triangles passage than Baxter’s or Sleigh’s. (Note that Sleigh’s interpretation is of an argument common to the two triangles passage and others.) See Baxter (1995) and Sleigh (1990); see Levey (2003, p. 275, fn. 38) for discussion of them.
Two other interpretations of the two triangles argument, consistent with Leibniz as a non-realist: (1) Levey got the interpretation of the argument right but Leibniz isn’t endorsing the argument. Levey considers this and I discuss his response in the next section. (2) Levey got the interpretation of Leibniz right and Leibniz believes there are bodies and they are essentially merely extended, he just denies they are substances. The argument is a reductio of (R1) rather than (R2). This is an intriguing view—Garber attributes something like it to Fardella in Garber (2005)—and I think it makes good sense of the early parts of the Leibniz–Arnauld correspondence.
I am not denying that Leibniz often says he is an organic body, an embodied soul. When I say one possibility is that Leibniz is a soul, I have in mind the position Adams ascribes to Leibniz in his (1994). Whether or not you are convinced by Adams’s reading, it is a live possibility.
The project of explaining away all Leibniz’s apparent assertions of realism is too much for one paper. I do think that the vast majority of those assertions in the correspondence can be explained away as I explained away the assertion Levey fastens on to.
That talk of one is tantamount to talk of the other is endorsed at G II: 58/LA: 65; G II: 58/LA: 66; G II: 71/LA: 87; G II: 72/LA: 88; G II: 72/LA: 89; G II: 73/LA: 89; G II: 75/LA: 93; G II: 76/LA: 94; G II: 92/LA: 115; G II: 100/LA: 125; G II: 116/LA: 149; G II: 118/LA 151; G II: 120/LA: 154.
I am thinking of “To assert that every substance which is not divisible (that is to say…every substance…) is a mind and must think seems to me incomparably more audacious…than the preservation of forms” (G II: 121/LA: 154–155). To my ear, this strongly suggests that some substances are minds, that is, thinking souls (G II: 120/LA: 154). What is so audacious is thinking only minds could be substances.
Like Sleigh, I assume that Leibniz holds that at least some forms, souls, are substances. Sleigh defends this in Sleigh (1990, p. 116) and Mercer et al. (1995, p. 111). See G II: 68/LA: 84; G II: 74/LA: 92; G II: 75/LA: 93; G II: 83/LA: 104; G II: 99/LA: 124; G II: 113/LA: 146; and, G II: 117/LA: 150–151. I think the textual evidence supporting that souls are substances is a bit more explicit than Sleigh does. Sleigh singles out the first passage as the only totally clear statement of the thesis that souls are substances but many of the others make no sense without that thesis.
Way #2 is, I believe, how Sleigh would have Leibniz connect DWW to SWR. My views about what is going on with regard to forms in the Leibniz–Arnauld correspondence are close to his.
Note, too, that Leibniz believes unity is provided at and over time via causation. See Sleigh (1990). There is no need for a thing to have parts to see how it could be unified in this way. If causation provides unity, it could do so for simple things as well as complex ones. For more on this, see my “Mental Atoms” (ms).
See G II: 47/LA: 52; G II: 51/LA: 57; G II: 57–58/LA: 64–66; G II: 69/LA: 84; G II: 70/LA: 86; G II: 71/LA: 92; G II: 78/LA: 96; G II: 113/LA: 146; G II: 124/LA: 159.
What expression comes to is an important, difficult question. The answer to it is, I think, unimportant for my purposes. What is important is Leibniz’s idea that a form is needed to do the expression, whatever, exactly, expressing comes to.
See G II: 47/LA: 51; G II: 57/LA: 64; G II: 70/LA: 86; G II: 72/LA: 88; G II: 76/LA: 94; G II: 78/LA: 96; G II: 136/LA: 170.
Leibniz thinks substances need have many more features than this: they have to have a complete concept, be discernible from other substances, be incorruptible, indivisible, ingenerable, and “a world apart.” Something that is unclear to me is why Leibniz hammers at Descartes mainly on the issue of unity. For example, while he criticizes Descartes because if bodies were essentially merely extended, there would be no substances because no unities, Leibniz doesn’t, in the correspondence, at least, hammer away at the idea that if there is body–body interaction, there are no bodily substances. But Leibniz is committed to the idea that if there are substances, they don’t interact, and Descartes is committed to bodily substances interacting with other substances. (This last point is controversial but a very closely related point can be made without the controversy.)
To clear up something that seems odd about my view: earlier, I wrote that a mind needs a unifier. This suggests that minds have forms without being forms. I leave that possibility open here—and develop it some in “Mental Atoms”—but a more natural idea is that a mind with unity would be a form.
Obviously, there is a good question about how forms unify minds or bodies. Mercer (2004) is a recent discussion of Leibniz’s views.
This is just a punchy way of puttng things. Levey is not ignorant of the fact that the monad terminology does not show up in the Leibniz–Arnauld correspondence. Levey is just asking how Leibniz could possibly be talking about and just talking about mind-like substances. Cf. Garber (1992) where the realist challenge to Sleigh (1990) is bipartite: first, the evidence for idealism Sleigh presents isn’t that strong and, second, the idealist needs to explain away all Leibniz’s talk of bodies. The realist, by contrast, takes it at face value.
The interest persists. In his 9 October 1687 letter, Leibniz is still hammering away at questions of substantial forms and bodies and writes, “The problems that are raised on these topics originate inter alia from the absence usually of a distinct enough concept of the whole and part…” (G II: 120/LA: 153). I don’t want to rest too much on this passage since it is a bit unclear what “these topics” refers to. Still, I read Leibniz as saying that all these issues about substantial forms and bodies that he and Arnauld have been discussing are only of instrumental interest to him: they are tools to help him get clear on the relation between whole and part. (Note that Leibniz might not have put things this way in light of his claim that “no entity that is really one is composed of a plurality of parts…and those things that have parts are not entities, but merely phenomena” (A. VI, 4: 627/Ar. 271). I think he would have accepted the idea conveyed by the suspect terminology.)
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Acknowledgements
Thanks to Gregory Brown, David Christensen, Mark Kulstad, Samuel Levey, Don Loeb, Derk Pereboom, members of the Mark Kulstad’s Fall 2008 graduate seminar on Leibniz, members of the Houston Circle, and an anonymous referee for help with this paper.
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Doggett, T. Why Leibniz thinks Descartes was wrong and the Scholastics were right. Philos Stud 149, 1–18 (2010). https://doi.org/10.1007/s11098-010-9537-9
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DOI: https://doi.org/10.1007/s11098-010-9537-9