In this paper, I argue that Spinoza holds a perspectivalist view of mereological composition, a form of anti-realism. The paper has two parts: In the first half of the paper, I introduce interpretive puzzles for the standard realist reading of Spinoza’s mereology. In the second half of the paper, I discuss Spinoza’s positive view on mereological composition and present a perspectivalist reading that avoids the interpretive puzzles.
Spinoza often emphasizes that human beings, organisms, and ordinary objects are all ‘parts of nature’, yet he seems to insist that nature is not composed of parts. He argues that infinite quantity does not have a part/whole structure, yet he describes bodies as parts of spatial extension, which is his prime example of infinite quantity. What do we do with these tensions? These issues are especially pressing since Spinoza’s mereology appears to be pertinent to his central metaphysical and ethical commitments: consider substance monism, or the idea that human beings flourish if they cooperate with each other as if they composed a single agent.1 Nevertheless, most contemporary interpreters tacitly rely on an account of Spinoza’s mereology in order to explain his views on issues such as persistence, minds, infinity, and the nature of extension.2 These accounts share the assumption that Spinoza is a realist of some sort about composition. In this paper, I make a case for reading Spinoza as an anti-realist instead.
According to the reading I offer in this paper, Spinoza is an anti-realist about composition because he is a perspectivalist. This means that for Spinoza, expressions such as ‘x is a part of y’ or ‘x is a whole composed of some ys’ convey abstract judgments from a particular limited perspective.3 In this way, my positive proposal is indebted to the perspectivalist interpretation of Spinoza’s account of composition previously advanced by William Sacksteder which has been largely neglected.4 A consequence of the perspectivalist interpretation is that parts and wholes are intentional objects that only exist as the content of abstract mental representations. Accordingly, I argue that Spinoza treats mereological composition akin to relations, numbers, universals, and abstract terms. Nevertheless, in my reading Spinoza does not consider mereological discourse as erroneous or lacking truth-value. Rather, Spinoza holds the non-standard view that the truth or falsity of mereological propositions depends on the particular perspective from which they are evaluated.5
Here is how the paper proceeds. In §2, I discuss a set of puzzles that pose a problem for the standard realist reading of Spinoza’s mereology concerning ordinary objects and organisms. In §3, I defend the perspectivalist reading by comparing Spinoza’s treatment of mereology to contemporary mereological fictionalism, and to Spinoza’s various discussions concerning abstraction and beings of reason [entia rationis]. Then I address whether Spinoza is entitled to rely on substantive claims about composition in his philosophy given the perspectivalist interpretation. I propose a positive answer, according to which Spinoza uses mereological idioms to abstractly describe intermodal casual interaction and dependence relations within a substance-mode ontology.
It is natural to think that ordinary objects are composed of parts that can exist separately from each other. In Spinoza’s period, separability in existence was often considered a mark of being a substance, that is, roughly speaking, an independent bearer of properties or features.6 However, as is well-known, Spinoza pushes back against this intuitive view on multiple occasions. As such, Spinoza is standardly interpreted as holding that the parts of ordinary objects, just like the objects themselves, are not independent from each other, as they are modifications of God—the only metaphysically possible substance in his metaphysics.7 In this section, I begin by briefly summarizing a principle playing a key role in Spinoza’s arguments against substance-composition, then show how the application of this principle leads to interpretive puzzles for the standard reading concerning Spinoza’s mereology of modes.
The principle that Spinoza employs to argue against substance-composition says that parts are always conceptually prior to the wholes they compose:
Conceptual Priority of Parts (CPP): For all xs and ys, if the ys compose x, then the ys must be conceived in order to conceive x.8
The CPP principle captures the intuitive idea that if something is composed of parts of a certain kind, then a proper understanding of this thing should reflect this fact. For example, arguably a mechanical clock cannot be properly understood without noticing that it is composed of cogs, wheels, springs, and so on. We can see the CPP principle working in the following passages:
[If a substance were composed of parts with different attributes, then] the parts (by 1p2) would have nothing in common with their whole, and the whole (by 1d4 and 1p10) could both be and be conceived without its parts, which is absurd, as no one will be able to doubt. (1p12d)
they talk utter nonsense, not to say madness, who hold that Extended Substance is put together of parts, or bodies, really distinct from one another. This is just the same as if someone should try, merely by adding and accumulating many circles, to put together a square or a triangle or something else completely different in its essence. (Ep.12/IV:55)
The key idea here is that substantial attributes are conceptually independent of each other (1p2). This means that in a situation where a whole has a different attribute than its parts, we are supposed to be able to adequately conceive a whole composed of parts without giving any consideration to the parts that are supposed to explain its features. If CPP is true, this is impossible. As such, given that Spinoza defines substance as conceptually independent of anything besides itself (1d3), it is no surprise that he ends up concluding that substances are generally indivisible.9
However, CPP in itself doesn’t seem to rule out that modes of the same attribute compose other modes. That is, assuming CPP, an ordinary object, which is a mode of extension for Spinoza, might be composed of other modes of extension through which in this case it must be conceived. Accordingly, the idea behind the standard interpretation is that although Spinoza holds that God—even considered as an extended substance—is not composed of parts, he clearly relies on theorizing about how modes enter into mereological relations. For example, consider the following:
parts are distinguished in [matter] only insofar as we conceive matter to be affected in different ways, so that its parts are distinguished only modally, but not really [partes modaliter tantum distinguuntur, non autem realiter]. (1p15s/II:59, emphasis added)
By singular things I understand things that are finite and have a determinate existence. And if a number of Individuals so concur in one action that together they are all the cause of one effect, I consider them all, to that extent, as one singular thing [ut unam rem singularem considero]. (2d7)
When a number of bodies … communicate their motions to each other in a certain fixed manner, we shall say that those bodies are united with one another and that they all together compose one body or Individual [omnia … unum corpus sive individuum componere], which is distinguished from the others by this union of bodies. (2p13sd/II:99–100, emphasis added)10
As such, according to the standard reading of these passages, Spinoza considers ordinary objects—and other finite bodies—as modes of extension, and in some cases, especially when they collectively perform an action, these modes compose other modes that contain them as parts.11
Now, as is well-known, Spinoza holds that nature has a hierarchical order of ontological dependence, going from God to God’s finite modes, such as ordinary objects and the bodies and minds of human beings. However, between God and finite modes, Spinoza somewhat idiosyncratically posits a special category of entities—that are often termed as ‘infinite modes’ in the literature—that are supposed to be more fundamental than regular bodies and minds. What matters for us here is that Spinoza also refers to finite modes as ‘parts’ of these infinite modes.12 For example, Spinoza famously refers to this passage when he is prompted to provide examples of infinite modes:
a composite Individual can be affected in many ways, and still preserve its nature. So far we have conceived an Individual … which is composed of the simplest bodies. But if we should now conceive of another, composed of a number of Individuals of a different nature, we shall find that it can be affected in a great many other ways, and still preserve its nature. …
But if we should further conceive a third kind of Individual, composed … of this second kind, we shall find that it can be affected in many other ways … And if we proceed in this way to infinity, we shall easily conceive that the whole of nature is one Individual, whose parts, i.e., all bodies, vary in infinite ways, without any change of the whole Individual. (2p13sl7s, emphasis added)13
The passage elucidates Spinoza’s definition of an individual (2p13sd from above) by taking it to apply to wider and wider frames, up to the point that it follows that all bodies together compose the whole of nature, here understood as the mediate infinite mode of extension.14 Spinoza discusses this together with the basic intuition that ordinary objects can change their internal constitution to some extent and still remain the same thing. For example, an apple seed’s constitution changes quite a lot during the time in which it grows into an apple tree, but we can still consider it to be the same thing. And nature as a whole is no different in this respect from ordinary objects, as its internal structure is constantly changing while it remains the same thing.
So far this is all well and good and compatible with CPP. But here is a problem: Although the passage above may somewhat misleadingly suggest that we need to conceive finite bodies first in order to conceive an infinite mode of extension, as it was pointed out previously by Garrett, we have good reason to doubt that this is Spinoza’s actual view.15 For in the series of propositions where Spinoza introduces infinite modes (1p21–23), he makes it quite clear that they must be conceived either directly through God’s attributes or through a chain of other infinite modes that are themselves conceived through God’s attributes. If so, infinite modes should be conceptually independent of any collection of finite modes. However, if infinite modes could be conceived without finite modes, CPP tells us that they are not composed of finite modes either.
Allowing that infinite modes are conceptually independent of finite modes, a mode-composition realist should either deny that infinite modes have parts (while holding that finite modes have parts), or deny CPP. Nevertheless, both of these options are problematic. First, as we saw above, Spinoza’s argument against substance-composition relies on CPP. Second, if the infinite modes in question were somehow exempt from having a mereological structure, while finite individuals aren’t, then it is unclear why Spinoza would discuss infinite modes directly as an extension of his definition of composite individuals.16
A second, related puzzle directly concerns Spinoza’s robust conception of infinity.17 Spinoza provides several arguments for the conclusion that infinite sequences—such as an infinite plane in Euclidean geometry—are not composed of finite parts. These arguments are motivated by Spinoza’s assessment of a few pre-Cantorian paradoxes resembling Hilbert’s hotel (see, e.g., the beginning of 1p15s). In a nutshell: take some infinite quantity, slice it up or add to it in some way or another, and then you have a multiplicity of lesser or greater infinite quantities. It is a well-known fact that paradoxes of this sort motivated people to reject actual infinity altogether. But, as is often the case, one philosopher’s modus ponens is another’s modus tollens: Spinoza decides to get rid of the underlying assumption that infinite quantity has a part/whole structure instead (cf. KV 1.1/I:18).
Although Spinoza mainly focuses on infinite substance in these passages, it is clear that he takes these arguments to rule out realism about composite infinite modes as well. Consider the following:
From everything now said, it is clear that some things are infinite by their nature and cannot in any way be conceived to be finite [nec ullo modo finita concipi posse], that others [are infinite] by the force of the cause in which they inhere, though when they are conceived abstractly they can be divided into parts [ubi abstracte concipiuntur, in partes possunt dividi] and regarded as finite (Ep.12/IV:60–61, emphasis added; cf. 1p15s/II:59).
This is getting to the topic of next section, but notice how Spinoza lays out the options here. There is substance, that is, something infinite by nature, and a substance is always infinite, even if we think about it abstractly, since it ‘cannot in any way be conceived to be finite’. And then there are things that are infinite because they are caused by something infinite. By 1p21–23, we have good reasons to think that these include Spinoza’s infinite modes. Spinoza says that when these kinds of infinite things are conceived abstractly, they are divisible into finite parts, but then they are represented as finite things, especially in light of the paradoxes about transfinite quantities.18
Now it may be that Spinoza only worried about infinite quantities composed of substances. If so, then it is unclear how infinite modes are exempt from Spinoza’s own arguments that should apply to any infinite quantity. And it will be all the more puzzling why Spinoza claims that composition and division only occurs in abstract thought.
I admit that infinite modes are among the more difficult aspects of Spinoza’s metaphysics. Perhaps we should not put too much weight on them, as it may be the case that Spinoza did not think all these implications through and he simply just left us with an unstable account. Nevertheless, these puzzles should at least motivate us to consider an alternative reading. As such, I move on to substantiate a reading according to which Spinoza considered all of mereology as a kind of abstract thinking. Once I unpack the view, one may consider the textual evidence that I lay out as an additional puzzle for the realist reading: why does Spinoza treat judgments about composition as abstractions if he is a realist about mode-composition?
Spinoza often warns about the pitfalls of reifying our everyday intuitions about parts and wholes. For example, in the early Short Treatise, he remarks that ‘part and whole are not true or actual beings, but only beings of reason … in Nature [i.e., in substantial extension] there are neither whole nor parts’ (KV 1.2/I:24, my emphasis). He also makes a direct comparison to universals in this context:
the whole is only a being of reason and differs from the universal only in these respects: that the universal is made of various disunited individuals, whereas the whole is made of various united individuals, and that the universal includes only parts of the same kind, whereas the whole includes parts of the same kind and of another kind. (KV I:32–33)19
If we take these remarks at face value, we get a reading that only beings of reason have a part/whole structure. If we take into account that Spinoza makes these remarks while discussing the reasons why the one substance is not composed of its modes, we get a reading that our intuitions that seemingly support mereological realism are based on epistemically flawed abstractions.20 As such, I will discuss evidence that suggests that Spinoza treats mereological propositions as a context dependent, interest laden, and ontologically lightweight. And in light of this, we should read Spinoza’s positive claims about mode-composition merely as useful locutions or approachable elucidations. The basic idea is that since we—but presumably not God—understand reality in terms of parts and wholes from a particular limited perspective, mereology is profitable for scientific reasoning and for understanding our own cognitive life. Nevertheless, as I will argue, Spinoza—especially in his mature works—retains the truth of mereological propositions about modes by radically revising their semantic content.
Let me take a slight detour to contemporary mereological fictionalism before we get to Spinoza’s perspectivalist account. As we will see shortly, contemporary fictionalism is concerned with the truth of everyday speech in light of revisionist metaphysical positions, and it is worth noting that Spinoza is not concerned with ordinary language this way. As such, we cannot attribute to him a modern fictionalist account without risking an anachronistic interpretation. Nevertheless, contemporary fictionalism will still prove to be helpful for framing Spinoza’s perspectivalist discussion of mode-composition.
Why be a fictionalist about composition? Consider the fact that for all we know, mereological nihilism may be true, so it may be the case that strictly speaking nothing composes anything. Or maybe we will never be able to make up our minds about the metaphysics of mereological composition. Should we rid ourselves of thinking and talking about parts and wholes? We might do so when the philosophical stakes are high, but otherwise it is hard to let go of the convenience of everyday talk about parts and wholes. There is an urge to explain the appeal of ordinary mereological talk even if we are convinced of a counterintuitive account such as nihilism; and even in light of possibly unsolvable metaphysical debates. This is the point where fictionalism may start to look promising.
Rosen and Dorr provide an illuminating example that is worth quoting at length here:
When the chemist says that a water molecule is made of two atoms of hydrogen and one of oxygen, he does not take himself to be speaking figuratively. If you ask him whether his claim is meant to express the sober truth, he may well say, ‘Yes, of course; this is serious business.’ Nonetheless, apprised of [the disputes on the metaphysics of composition] he may be inclined to back off from his confident claim about composition. If he is canny he may say, ‘I’m not sure whether what I said is strictly true. But what I am sure of is this: what I said was true on the assumption that composite things such as molecules exist.’ (2007: 169)
As Rosen and Dorr put it, mereological fictionalism conveys pretense with linguistic operators such as ‘according to the fiction of mereology’ or ‘on the assumption that composition occurs’. Notice that the operators are supposed to be tacit in most cases, but we can always make them explicit in order to clarify why we take mereological propositions to be true, even though they may be literally false. Consider the following pair:
1 and 2 are clearly independent from each other: if chemical bonding is not sufficient for composition, 1 is false while 2 remains true. In principle, we could introduce any operator of the form ‘on the assumption that …’. However, the appeal of fictionalism is that it accommodates the pretensions that are related to our interests. So, for example, the truth of 2 from above is not entirely due to its mereological assumption, as it is also contingent on the fact that there is a chemical bond between the atoms.21
Notice that this is not entirely different from our attitudes towards figurative speech in general. Rosen and Dorr give the following example for contrast:
Consider the mariner who knows full well that Copernicus was right. When he is navigating he speaks and thinks in Ptolemaic terms. In the midst of a storm, when things are urgent, he may have no conscious reservations about what he says or thinks. Nonetheless, when he says ‘If Venus has crossed the moon, we’re off course’ he is not committed to its truth. His official view, his genuine view, is that Copernicus was right and that his Ptolemaic remark is a useful fiction. (Rosen and Dorr 2007: 170)
So, even if we are convinced that composition never occurs, it makes life easier to assume a sort of folk-mereology according to which chemical bonding is sufficient for composition—just as it is often more practical to pretend that Venus is crossing the moon, even if we know all well that Copernicus was right. After all, we may agree in the case of the chemist that the relevant chemical structure is there, even if we disagree about whether it really is a case of mereological composition.
The closest Spinoza gets to contemporary fictionalism is his rich discussion of beings of reason: universals, relations, numbers, shapes, negative properties, etc., are all treated as a being of reason at some point. However, in contrast to contemporary fictionalists, Spinoza retains the medieval terminology of ‘beings of reason’ that stresses the cognitive function of the target discourse as opposed to its usefulness in ordinary language. Perhaps this is most explicit in the CM, where he defines beings of reason as ‘nothing but a mode of thinking, which helps us to more easily retain, explain, and imagine the things we have understood’ (CM 1.1/I:233). For example, consider Spinoza’s treatment of privation (see Ep.21/IV:128; CM 1.1/I:234): the predicate of being ‘blind’ is a privative predicate (i.e., ‘lack of sight’), and in Spinoza’s view it merely conveys our comparisons between people who can see and people with positive features so distributed that they lack the ability of sight.
In addition, it is worth noting that Spinoza distinguishes between the terms ‘fiction’ and ‘being of reason’ (see CM 1.1/I:236): On the one hand, fictional entities are completely invented and their only connection to reality is that people think about them. For example, fictional entities are the likes of the legendary fountain of youth or characters such as Pantagruel. On the other hand, beings of reason are abstract representations of something real, and we rely on these abstract representations in order to perform cognitive tasks.22 As such, paradigmatic beings of reason are mathematical representations of ordinary objects. For example, consider simple geometrical representations of billiard balls that take them to be a prefect spheres in Euclidean space to make it easier to calculate where to hit them for a particular effect. In light of this, Spinoza’s account of beings of reason has more similarities to idealizations in scientific modeling than to fictionalism. That is, while contemporary fictionalism may be understood as prioritizing ordinary language—albeit not independently of its cognitive utility—Spinoza seems to put full emphasis on the cognitive utility of certain abstract ways of thinking.23
Spinoza seems to make a direct connection between being in error and relying on beings of reason while one is making a case for a certain metaphysical view. One may even argue that for Spinoza, the reification of certain beings of reason is the most severe philosophical error one can ever fall into.24 Consider the following:
We see, therefore, that all the notions by which ordinary people are accustomed to explain nature are only modes of imagining, and do not indicate the nature of anything, only the constitution of the imagination. And because they have names, as if they were of beings existing outside the imagination, I call them beings, not of reason, but of imagination. So all the arguments in which people try to use such notions against us can easily be warded off. (E1app/II:83, emphasis added)25
Let’s stop for a second to assess the main idea here. Somewhat unsurprisingly for a keen rationalist, Spinoza maintains that sense-perception is the only possible source of error (see 2p41). And ‘imagination’ is a technical term that he uses to characterize sense perception and everything else that depends on sense perception in some way or another—for example, memories of sense perception, abstractions from sense perception (including fictional entities), and so on (see, e.g., 2p40s2). The point about names here is nothing new; Spinoza often insists that the nouns we use in ordinary language do not have a one-to-one correspondence with the things that exist in reality:
since words are part of the imagination, i.e., since we feign many concepts, in accordance with the random composition of words in the memory from some disposition of the body, it is not to be doubted that words, as much as the imagination, can be the cause of many and great errors, unless we are very wary of them. (TIE 88/II:33, emphasis added)26
Consider fictional entities: according to Spinoza, the name ‘Pantagruel’ only corresponds to a mental representation and not to a flesh and bone scholarly giant. And Spinoza has a similar attitude towards entities in general that feature in our sense perception, since our mental representations leave it open whether there is anything real that they correspond to. We should resist making metaphysical conclusions about entities just on the basis of having a piece of language that singles them out.27
However, this is not to say that attending to sense perception necessarily leads to epistemic error: Spinoza is clear that he thinks that imagination cannot lead us astray if we are aware of the epistemic status of the representational content of sense-perception. And so Spinoza insists that we are not in error just by, for example, imagining that the sun is 200 feet away from earth, granted that we may be aware that it merely looks as if it is 200 feet away (2p35s; 4p1s). Similarly, we are not in error when we read a fictional novel, given that we do not take it to be an account of events that actually happened.
Remember that we briefly touched upon how Spinoza applies this idea to composition in §2. I would like to put forward another quote here which neatly summarizes his diagnosis that composition belongs to abstract thinking:
If someone should ask now why we are … so inclined to divide quantity, I shall answer that we conceive quantity in two ways, abstractly or superficially, as we imagine it, or as substance, which is done by the intellect alone. So if we attend to quantity as it is in the imagination, which we do often and more easily, it will be found to be finite, divisible, and composed of parts; if we attend to it as it is in the intellect … it will be found to be infinite, unique, and indivisible. (1p15s)28
Clearly, the problem is not that we imagine that some extended thing is composed of parts. This is something we cannot help, since this is just how our sense perception works. So, the point is that even if we can distinguish parts of extension in imagination, this in itself is not sufficient to conclude that these parts are different extended substances. And if we are able to rationally perceive the nature of extension, assuming that Spinoza’s arguments are successful, extended things do not have a part-whole structure.29
My assessment of the evidence so far doesn’t take into account a specific interpretive problem that Spinoza’s discussion of beings of reason presents to his readers. The problem is that after Spinoza repudiates a discourse, he often attempts to reclaim the terms that he diagnoses as beings of reason by introducing new deflationary definitions for them.30 It seems that at least part of Spinoza’s intention in doing this is to make his points accessible, or to explain cognitive life from a human standpoint; but unfortunately this move often backfires since he does not always flag the intended sense of the relevant terms afterwards.31 In what follows, I will discuss this issue focusing on Spinoza’s treatment of mereological discourse.
Spinoza dedicates almost an entire letter (Ep.32) to explaining his account of mode-composition. In this letter, he famously invokes a thought-experiment involving a ‘worm in the blood’: according to Spinoza, our everyday experience is comparable to the experience of a microscopic worm living in a bloodstream that encounters microscopic cells. From the worm’s perspective, the cells are separate wholes. But from a different perspective the whole bloodstream may just look like one integrated system with no distinguishable internal structure. By analogy, we may be able to distinguish ordinary objects around us, whereas they are really not all that different from a wider point of view. This is how Spinoza summarizes the takeaway:
I consider things as parts of some whole to the extent [eatenus] that the nature of the one adapts itself to that of the other so that they agree with one another as far as possible. But insofar as [quatenus] they disagree with one another, to that extent [eatenus] each forms in our Mind an idea distinct from the others, and therefore it is considered as a whole and not as a part. (Ep.32/IV:170a–1a, emphasis added)
A natural reading of this passage suggests that Spinoza here treats ‘being a part’ and ‘being a whole’ as a matter of degrees: some objects disagree with each other to some extent and so we represent them as distinct objects in our minds. But these different objects also get represented as parts of a larger whole to the extent that they are in some relative agreement from a different perspective.32 In this sense, the more similar the objects are, the more reason we have to consider them as parts; and the more dissimilar they are, the more reason to consider them as wholes. This account allows for flexibility, since we may adopt different perspectives and our judgments about composition will follow along.33
There is also a crucial detail about the ‘nature’ of things adapting to each other. Let me unpack this idea with a concrete example: consider Peter helping Paul move his sofa. We may recognize that Peter, Paul, and the sofa exercise relatively dissimilar patterns of motion. To this extent, each of them should be taken to be a whole object on its own. However, Peter and Paul, and to some extent the sofa, work together, so we should also recognize that they have to be able to coordinate and adapt to each other’s patterns of motion. The more similar they become as a result, the more they can be represented as a part of a whole composed by these three individual patterns of motion. But if we zoom in, so to say, we will find out that all of them are in fact just collections of smaller things acting together, much in the same way as Peter and Paul coordinate their motions. And we can also zoom out and adopt wider and wider points of view: we can take their immediate environment into consideration, or other humans performing similar tasks. What is more, the city, the continent, etc., are all exercising some unified pattern of motion that Peter and Paul are parts of. And as we saw in §2, this mental exercise terminates in a representation of the whole of nature as an integrated system of coordinated action.34
Let’s revisit Spinoza’s most direct discussion of mode-composition in the Ethics:
if a number of Individuals so concur in one action that together they are all the cause of one effect, I consider them all, to that extent [eatenus], as one singular thing. (2d7, emphasis added)
When a number of bodies … communicate their motions to each other in a certain fixed manner, we shall say that [dicemus] those bodies are united with one another and that they all together compose one body or Individual, which is distinguished from the others by this union of bodies. (2p13sd/II:99–100, emphasis added)
In light of the above, I suggest that these definitions introduce terms that convey comparisons between modes in terms of their joint causal activity from a particular perspective: if some modes act together, then they are becoming more and more similar, and this means that to some extent we can abstractly represent them as having a part/whole structure. This is comparable to the case of the chemist from above. Recall that the chemist tacitly assumes that chemical bonding is sufficient for composition in order to illustrate the structure of a water molecule. Since, for all we know, facts about chemical structure don’t rely on facts about mereological composition, the chemist’s tacit assumption doesn’t make a difference to the point that he is trying to convey by claiming that two oxygen atoms and a hydrogen atom compose water. Similarly, Spinoza considers modes as composing an object because from a limited perspective we may recognize that they are similar to some extent when they act in unison, which is true independently of whether this is really a case of composition.
One may wonder whether adopting perspectivalism about composition means that Spinoza considered the individuals themselves to be abstractions. One may even worry that perspectivalism is yet another way to tacitly attribute acosmism to Spinoza, thereby undermining any plausible motivation for Spinoza to write the Ethics. For example, if there are no individuals, we don’t exist either, so why should we bother with understanding the nature of our affects in order to overcome suffering that isn’t even real in the first place?
Even though I don’t think we should reject acosmist readings just on the basis that it raises these issues for Spinoza’s philosophical project concerning finite entities, it is important to alleviate these worries if possible. Luckily, in my understanding the perspectivalist reading doesn’t imply acosmism. What perspectivalism does imply, is that the application of mereological idioms to actually existing finite modes essentially involves taking up a limited perspective, because finite modes have no mereological structure—they are neither simples, nor composites—independently of some finite mind taking an attitude towards them. Spinoza defines singular things as ‘things that are finite and have a determinate existence’ (2d7), and not as entities that are essentially composed of finite modes. Now although he adds a clause to this definition that many individuals acting together will be considered as one singular thing, from this it doesn’t follow that the entity in question is not a mode that is better characterized with the help of other, more fundamental idioms of ontological dependence. For example, Spinoza defines modes by using inherence (1d5), and perspectivalism can accommodate the reality of modes related by inherence to both the substance and perhaps to other modes. The same goes for the familiar relations of causation and conception. So, as I understand perspectivalism, it is compatible with claiming that there are finite modes that are in causal relations with other finite modes (1p28); or that there are modes that are conceived through God (1p15). As such, adopting perspectivalism doesn’t imply acosmism because it maintains that modes have their fundamental features independently of some finite mind taking an attitude towards them. On the perspectivalist reading, when Spinoza uses mereological idioms to advance a point concerning finite modes, it is an abstract way of describing a set of more fundamental relations between finite modes while ignoring others.
A related objection could be made that perspectivalism appears to undermine certain aspects of Spinoza’s ethical theory. Consider the following:
It is the part of a wise man … to refresh and restore himself in moderation with pleasant food and drink, with scents, with the beauty of green plants, with decoration, music, sports, the theater, and other things of this kind … For the human Body is composed of a great many parts of different natures, which constantly require new and varied nourishment, so that the whole Body may be equally capable of all the things which can follow from its nature. (4p45s, emphasis added)
On the face of it, the passage says that the powers of the human body depend on the powers of its parts. Nevertheless, a perspectivalist can accommodate this point in the following way: from a certain limited perspective, the powers of the human body can be considered as constituted by the powers of a set of discrete finite modes that are considered as its parts. But this is not to say that the human body really consists of a set of discrete parts, independent of perspective. For example, from a different perspective, the human body, with no regard to its intrinsic structure, can be considered as merely a part of some larger integrated whole, for example when it performs a dance with others, or constitutes a state as one of its citizens (see e.g., 4p18s/II:223). However, at the same time, the human body itself isn’t an abstraction, but a finite mode fundamentally related to the substance and other modes through the familiar Spinozistic relations of inherence, conception, and causation.
There is another important objection that we need to address, especially because this objection makes the tacit assumptions behind realist readings explicit. Here is the objection: if Spinoza analyses mereological terms as functions of causal activity, why can’t he be a reductionist about mode-composition after all? Reductionism in this case means that Spinoza simply identifies parts and wholes with modes coordinating their specific motion and rest.35 So, according to this view, it is literally true that modes are parts of a larger whole just in case they ‘adapt’ to the causal activity of other modes. Let’s also grant that the puzzles I discussed in §2 can be played down in some way or another. For example, we may concede that those puzzles only present a genuine challenge to Spinoza’s theory of infinite modes. But if we bracket those issues for now, it seems that we have a perfectly good reductionist and realist account of mode-composition in the realm of finite modes.
To assess this objection, let’s turn to the account of bodies that Spinoza presents in his Physical Digression after 2p13s. Consider the following:
A body which moves or is at rest must be determined to motion or rest by another body, which has also been determined to motion or rest by another, and that again by another, and so on, to infinity. (2p13sl3)36
Spinoza stresses here that bodies always perform their basic activities—motion and rest—in relation to the causal nexus that encompasses the activities of other bodies. However, there are good reasons to think that pairing this with a reductionist account of composition comes with enormous epistemic costs. This is so because Spinoza holds that in order to cognize causal relations we also need to cognize their grounds:
The cognition of an effect depends on, and involves, the cognition of its cause. (1a4, translation altered)37
So, if the causal activity of a finite mode A is an effect of the causal activity of another finite mode B, then we need to cognize B in order to cognize the causal activity of A.38 However, with regard to 2p13sl3 and 1a4, if our goal is to fully understand that a certain body is in a certain motion, we will need to fully understand an infinite chain of causes. As Spinoza puts it:
every body, insofar as it exists modified in a definite way, must be considered as a part of the whole universe, must agree with its whole and must cohere with the remaining bodies. (Ep.32/173a)39
It is possible now to state the main issue with the reductionist reading that I cashed out above. First of all, it is clear that for Spinoza there is a privileged perspective that encompasses all finite modes together and all their specific causal activities. Spinoza has this in mind when he makes the following statement:
I don’t know how [parts of Nature] really cohere and how each part agrees with its whole. To know that would require knowing the whole of Nature and all of its parts. (Ep.32/IV:170a)
Now to make it clear why this is in tension with a reductionist reading, consider the example of a simple billiard ball rolling. According to the reductionist reading, it is strictly true for Spinoza that the billiard ball is composed of particles that are performing similar causal activities, namely that they are rotating in such a way together that they form the shape of a ball. But let’s consider the situation from a wider perspective: it is apparent that the specific motion of any of these particles come from all sorts of distinct causal influences. And taking this into account, we should rather judge that the particles making up the ball from our initial perspective are not uniquely similar after all. This is so because from this wider perspective the relative similarity between them decreases to a certain degree, while at the same time their similarity increases in relation to all sorts of other things. But this also means that on the reductionist reading our billiard ball is a whole to a much smaller extent. And if we consider the situation from the privileged point of view of 2p13l7s and Ep.32 that takes into account the infinite whole of extended nature, it turns out that the particles making up the billiard ball are even more similar to everything else in the whole of nature. So, adopting the widest possible perspective, the reductionist is committed to claiming only the totality of nature appears to be a whole, while everything else is merely a part.40
At this point, one may object on behalf of reductionism by pointing out that it is compatible with acknowledging that the composition relation is gradable in this way. The reductionist may even concede that the particles making up our billiard ball are similar to each other to a much smaller extent than the similarity each of them bears to the rest of nature. However, the objection continues, from this it does not seem to follow that the billiard ball is not a whole. Rather, what follows is that the billiard ball is a whole to a much smaller extent than the whole of nature. But notice that even if this is true, from the widest possible perspective the similarity between any finite set of modes is infinitely smaller than the similarity between all of them. So, on a gradable reductionist account of composition, every finite composite, including our billiard ball, is a whole only to an infinitely small degree. If so, if the reductionist still wants to hold that different degrees of composition are grounded in genuine differences in degrees of causal interaction and similarity, they need a story about how Spinoza can accommodate differences between infinitesimal degrees of composition. And even though giving such an account is perhaps not impossible, facing such possibilities in Ep.12 and 1p15s Spinoza goes to great lengths to point out the importance of distinguishing abstraction from reality.
However, the perspectivalist reading has no such issues, because it does not try to reduce mereological notions to specific causal activities. On the contrary, it acknowledges that the truth of mereological judgments depends on assuming a limited perspective. These limited perspectives are abstractions, since they only take into account internal relations, that is, whatever is intrinsic to the causal activity of objects. In this way, we need not cognize the rest of the universe to recognize the harmonized motions intrinsic to, for example, the parts of a human body, a group of people, or particles in a bloodstream.
Lastly in this section, I will compare the perspectivalist reading to Samuel Newlands’s recent interpretation that takes the above observations seriously. According to Newlands,
Conceived narrowly, a region of motion and rest may contain hundreds of individual finite modes … Conceived more broadly, the region might instead contain just a single composite individual … But this implies that there are hundreds of finite modes in a region conceived one way, and that, conceived another way, there is only one finite mode in that region. (2018: 161)
Newlands doesn’t advance a perspectivalist reading since the core idea of his interpretation is that the so-called broad conception of things is not epistemically privileged (see, e.g., Newlands 2018: 155–60). On this reading, we don’t end up committing error just by taking up a limited perspective, and so we can make various seemingly contradictory judgments about composition that are all strictly true depending on the standpoint from which we are evaluating them. As such, Newlands defends a realist and reductionist view about composition that takes each ‘narrow conception’—that is, each particular limited perspective—to have the same epistemic status as the broad conception. It is beyond the scope of this paper to do full justice to Newlands’s interpretation of Spinoza’s mereology, as it is a part of a systematic account of Spinoza’s whole metaphysical project. Nevertheless, in my reading, Spinoza takes the narrow perspectives to have a lesser epistemic status.41 In what follows, I briefly explore an alternative account—with an admitted focus on Spinoza’s mereological views only—according to which the broader perspective is privileged, even though the narrow, lesser kinds of perspectives may ground useful abstractions.
So, how do we avoid falling into error on the perspectivalist interpretation? After all, we may need justification that there are genuine similarities within a perspective which ground Spinoza’s lightweight semantics of mereological terms. Unfortunately neither the Ethics, nor Ep.32 is clear about the details.
One possible clue that I won’t look at in detail is CM 2.5/I:258, where Spinoza discusses things distinguished only by reason. It is unclear whether this line in the CM can be taken as evidence for Spinoza’s own account of composition. The problem is that distinctio rationis in the CM is introduced to explain the distinction between substance and attributes, whereas in the CM Spinoza also maintains the Cartesian line that the parts of extension are really distinct extended substances. This should at least raise suspicion that in the CM Spinoza is discussing a different account of composition than the one in the Ethics.42
Rather, I suggest that Spinoza’s epistemology of ‘common notions’, as it is laid out in the Ethics, may offer a good starting point for an account. According to Spinoza, the common notion of ‘motion and rest’ fundamentally characterizes everything in extension, as anything else they do is reducible to patterns of motion and rest.43 The idea is that it is straightforwardly true that each and every physical body is moving in some way or another:
all bodies agree in that they involve the concept of one and the same attribute (by 2d1), and in that they can move now more slowly, now more quickly, and absolutely, that now they move, now they are at rest. (2p13sl2d)
As such, in case our judgments about composition do not commit us to realism about parts and wholes, they can still be used figuratively to talk about genuine relations of motion and rest. Understood this way, they even express truths with the assumption that coordinated activity from a specific perspective is sufficient for composition.
The reading I offer elaborates on the bits and pieces we can find in Spinoza’s writings about composition. Unfortunately these passages are as specific as Spinoza gets about the details of how we can theorize about the composition of bodies with the help of motion and rest.44 Thus, although I think the reading I offered is Spinoza’s view, I am not thereby claiming that it is also a good view that satisfies all of our questions about composition, including but not restricted to questions that we may have about Spinoza’s account of composition in particular. Of course, one needs to be convinced by many of Spinoza’s radical metaphysical theses to be motivated to embrace perspectivalism about composition. As such, although I presented Spinoza as an early predecessor to contemporary mereological fictionalism, I don’t think he is motivated by the problems that contemporary metaphysicians care about. For example, Spinoza shows little interest in figuring out whether mereological nihilism or universalism is true.45
Nevertheless, Spinoza clearly takes into account that his highly unorthodox metaphysics would leave us unsatisfied if he could not account for our natural inclination to treat things as parts and wholes. And this aids his theoretical interests because questions about composition are relevant to Spinoza’s views on monism, persistence, the nature of the human mind, and even to his metaethics and political philosophy. And although I did not have much space to discuss this, it should be clear that adopting a perspectivalist stance on composition doesn’t undermine the substantive commitments he expresses in these domains.46
1For the latter point, see 4p18s. I use the standard system for referring to passages from the Ethics. E.g., 4p18s means Part 4, Proposition 18, scholium. All citations from Spinoza are from Gebhardt’s Opera (Spinoza 1925). The English translations are from Curley’s translation in Collected Works (Spinoza 1985, 2016). I also used the following standard abbreviations for works by Spinoza: CM = Cogitata Metaphysica, Ep = Epistolae, KV = Korte Verhandeling, TIE = Tractatus de Intellectus Emendatione. Other abbreviations: C = Categories in Aristotle (1984), M = Metaphysics in Aristotle (1984), CSM = Descartes (1984), Q = Ockham (1998), DM = Suárez (1947).
2See, e.g., Gueroult (1968: 500–528) on infinity. On individuation and persistence, see Barbone (2002), Garrett (1994), Lin (2005), Melamed (2013: 72–79), and Wartofsky (1977). On the eternity of mind, see, e.g., Garrett (2009), and Grey (2014). On spatial extension, see Bennett (1980; 1984: 89–110), Nadler (2012), Lachterman (1977), Schmaltz (1999), Smith and Nelson (2010), Peterman (2015), and Robinson (2009).
3While in classical mereology the default option is to take the parthood relation to be reflexive, in this paper I only consider parts that are not identical to their wholes. In the terms of classical mereology, I use the term ‘part’ to refer to proper parts. Cf. Simons (1987); Varzi (2016).
4See Sacksteder (1977, 1985). However, an important exception is Samuel Newlands, who cites Sacksteder and initially seems receptive to a perspectivalist reading, but he settles on a concept-dependent realist view that fits better with the interpretation that he offers concerning Spinoza’s general metaphysical project (2018: 136–68). I will come back to Newlands’s account in §3.
5In contrast to the account advanced by Ghislain Guigon (2012), according to which mereological definitions lack truth-value, but mereological propositions can be true because the truth of mereological propositions entirely depends on objective non-mereological facts. Cf. Rosenthal (2019) who similarly argues that parts and wholes are beings of reason and concludes that Spinoza held that mereological idioms—among other kinds of beings of reason—are evaluated in terms of their practical utility. I come back to discuss these accounts in note 42.
6The best example is Descartes Principles I 60 (CSM I:213). See also CSM I:226–8; II:30–31, 54, 157. For discussions on Cartesian mereology and its relation to substance, see Sowaal (2004), Normore (2007), Smith and Nelson (2010), and Schechtman (2016). It is worth noting that this general view is sometimes referred to as the doctrine of actual parts, which is contrasted with the doctrine of merely potential parts. On actual parts, see, e.g., Aristotle, C 5, 3a29–33; Ockham, Q IV.19; Suarez, DM 7.1.23; and Clarke and Collins (2011: 53); see Aristotle, M VII.13, 1039a7–8 and VII.16, 1041a4–5; and Leibniz (1997: 116–17), for potential parts. Perhaps a case can be made that Spinoza’s 1p12d and 1p13d contain an argument against potential parts, but a more direct argument is available through necessitarianism (1p35). For detailed overviews on early modern mereology, see Holden (2007), and Pasnau (2011: 610–12).
7It is worth noting that according to Spinoza, modes are in God (1d5), but they don’t compose God. See 1p13d; Ep.32/IV:173a. This is also a recurring theme in the two dialogues in his early Short Treatise, see, e.g., KV I:30; I:33. See Carriero (1995) for a thorough discussion. In addition, Peterman (2015) argues that Spinoza’s account of spatial extension, that he cashes out in terms of inherence instead of parthood, is therefore highly non-standard in the period.
8On the interpretation I take to be most plausible, CPP commits Spinoza to the traditional view that parts are ontologically prior to their wholes. Nevertheless, I don’t intend to defend this reading here since what follows only requires the weaker conceptual dependence expressed by CPP. But it is worth noting that there are good reasons to think that ontological and conceptual dependence are at least coextensive for Spinoza. In addition, Spinoza repeatedly alludes to the traditional view that parts are ontologically prior to wholes. For example, in CM 2.5 he writes: ‘it is clear through itself that component parts are prior in nature [partes componentes priores sunt natura] … to the thing composed’ (I:258); see also Ep.35: ‘component parts must be prior in nature and knowledge to what is composed of them [componentes natura, & cognitione priores sint oportet quam id, quod compositum est]’ (IV:181). For discussion, see Guigon (2012: 183–89), and Melamed (2013: 47–48).
9See, e.g., 1p13c and most of 1p15s. There is another argument in the Ethics for the same conclusion (1p15s/II:59) that I will not discuss here. The argument adheres to Spinoza’s rejection of vacuum, which is common ground between Spinoza and Descartes, since they both hold that extension is a continuous plenum. See, e.g., Principles II 16–18 (CSM I:230). For Spinoza’s rejection of vacuum, see, e.g., TIE 30/I:30; Ep.6/IV:32; and Ep.13/IV:65. For discussion on Spinoza’s mereology and the vacuum, see Bennett (1980; 1984: 89–110), Schmaltz (1999), and Smith and Nelson (2010: 12).
10In addition, Spinoza explains the epistemic limitations of finite minds by referring to their inadequate representation of the ‘parts of the body’ (2p24; 2p28; 2p29c); and he often expresses his strand of naturalism by claiming that a human being is a ‘part of nature’ (see, e.g., 4p2; 4p4; KV I:63–64).
11See, e.g., Garrett (1994); Lin (2005); and Grey (2014). Melamed (2013: 72–79) and Newlands (2018: 142–50) offer similar readings, although both point out that Spinoza’s discussion of composition is remarkably elusive.
13Schuller’s letter is worth quoting here: ‘I would like Examples of the things produced immediately by God, and those produced by the mediation of some infinite modification’ (Ep.63/IV:276a). Spinoza answers that ‘examples of the first kind are, in Thought, absolutely infinite intellect, and in Extension, motion and rest; an example of the second kind is the face of the whole Universe, which, however much it may vary in infinite ways, nevertheless always remains the same. On this, see 2p13sl7s’ (Ep.64/IV:278).
14It is worth noting that Spinoza explicitly distinguishes between two uses of the term ‘Nature’ [Natura]. See 1p29s/II:71; KV 1.8–9/I:47–48. On the one hand, ‘nature’ means substance that he terms as Natura naturans. On the other hand, Spinoza terms modes—including infinite modes—as Natura naturata, emphasizing that they are things in nature.
15See Garrett (1991: 198). Curley and Walski brings up a series of plausible objections to the idea that the mediate infinite mode of extension is composed by finite modes (1999: 253–54). However, in my view, Garrett (2018: 129) successfully addresses them.
16However, see Sangiacomo and Nachtomy (2018: 119–22) for an account arguably denying CPP. According to Sangiacomo and Nachtomy, ‘in the Ethics, God’s power cannot be conceived as prior to the power of finite things [because] God’s power is nothing other than the power through which finite things strive’ (2018: 119). In my reading, since Sangiacomo and Nachtomy also embraces the standard reading of Spinoza’s account of composition, their account leads to an interesting puzzle about the distinction between the power of the totality of finite modes and God’s power, even though the former is supposedly a modification of the latter. Nevertheless, Sangiacomo and Nachtomy ultimately settle with admitting the priority of God’s power over its parts (2018: 122). Thus their account implies the denial of CPP. In light of this, the reading they advance may be better served by perspectivalism, according to which neither God’s power nor the totality of finite modes is mereologically composed of individuals. In this way, embracing perspectivalism would help distinguishing between relations of composition and the determination relation their account ultimately relies on—cf. Sangiacomo (2015: 531).
18Cf. Melamed (2013: 128). Melamed takes the above comment to be evidence that infinite modes are in fact divisible. However, the textual evidence only substantiates the weaker claim that they can be abstractly represented as divisible.
19Similarly, in the early TIE he claims that we can fall into ‘great errors’ by failing to distinguish ‘between imagination and intellection’ and believing that ‘parts must be really distinguished from one another’ (TIE 87/II:33).
20Compare Newlands’s reading. After much struggle with these texts Newlands writes them off as ‘as a product of youthful exuberance’ (2018: 148). However, the context makes it clear that Spinoza is considering cases when the modes allegedly compose the substance, and so these quotes seem to be compatible with Newlands’s reading.
22Eklund (2017) makes a similar distinction and he terms the view in question as linguistic fictionalism, as opposed to ontological fictionalism which is roughly the view that certain entities have the same metaphysical status as fictional characters.
23See Rosenthal (2019) for a reading that specifically emphasizes the practical utility of beings of reason, including mereological notions. I agree that certain uses of beings of reason are justified on the basis of practical utility. However, in note 42 I discuss some worries about whether this is the case when it comes to Spinoza’s mereology in particular.
24CM 1.1/I:236; KV 2.4/I:60; 1app; 2p40s1; 2p49s. On this issue, see also Newlands (2017).
25Compare: ‘And if the Modes of Substance themselves are confused with Beings of reason of this kind, or aids of the imagination, they too can never be rightly understood’ (Ep.12/IV:57–58). See also Hübner (2016: 78–79).
26Cf. ‘people … give names to [mere modes of thinking], as if to signify beings existing outside our mind, which Beings, or rather Nonbeings, they have called beings of reason’ (CM 1.1/I:234, emphasis added).
27Proponents of easy ontology (see, e.g., Schaffer 2009; Thomasson 2010, 2014) will rightly protest this crude characterization of ontological commitment. However, although it is a perfectly viable question to ask whether Spinoza would have retained his view in light of contemporary arguments, it would lead us far from the focus of the present paper.
28See also Ep.12/IV:56–57, especially: ‘if someone strives to explain [things only graspable by the intellect] by … aids of the Imagination, he will accomplish nothing more than if he takes pains to go mad with his imagination.’
29For a great discussion on extension and divisibility that makes a convincing case for this interpretive point, see Peterman (2015).
31Perhaps this is most apparent in Spinoza’s discussion of moral terms. On the one hand, he insists that our judgments about moral good and bad only convey our faulty prejudices (see, e.g., 1app; 4pref). On the other hand, he also redefines ‘good’ as ‘what we certainly know to be useful to us’ (4d1) and goes on to make substantive claims about our ‘true knowledge of good and evil’ (4p16; 4p17).
33Sacksteder also emphasizes this point: ‘Any usage of vocabulary associated with part and whole is a function of what we, or the worm, or some other knower considers it to be’ (1977: 145).
34See 2p13sl7s; also in Ep.32 he writes that ‘every body, insofar as it exists modified in a definite way, must be considered as a part of the whole universe, must agree with its whole and must cohere with the remaining bodies’ (IV:173a).
35Arguably the standard reading of Spinoza’s account of composition is reductionist in this sense (see, e.g., Garrett 1994; Lin 2005; and Grey 2014). An anonymous reviewer wonders whether reductionism faces the challenge that a composite mode has no property to be reduced that the reductive base doesn’t already have. However, it seems to me that the reductionist account is compatible with Spinoza’s claims that a body can change parts while retaining its ‘ratio of motion and rest’, which may sufficiently block this challenge (see, e.g., 2p13sl4).
36See also Ep.32/IV:172a–173a. The idea here is in line with Spinoza’s general conception of finite modes in 1p28. Without getting too much into the details, Spinoza claims that finite modes must be caused by something finite, otherwise God or an infinite mode would cause them directly, which would automatically render them infinite modes (see 1p22).
37For related, although even more severe tensions in Spinoza’s account of relations, see Della Rocca (2012: 158).
38I take this to be compatible with the standard reading of 1a4. See, e.g., Bennett (1984: 129), Wilson (1999), Della Rocca (1996: 70), Garrett (2010: 106), and Melamed (2012: 181). However, for a more lightweight reading, see Morrison (2015). This is not the proper place to fully address Morrison’s arguments against the standard reading, but it is worth pointing out that the objections he makes concerning the conception of ordinary objects can be allayed by endorsing the anti-realist account of composition I defend in this paper.
39Spinoza uses this idea to substantiate 2p16, 2p24, and 2p30. See also 4p2: ‘We are acted on as we are a part of Nature, which cannot be considered through itself, without the others.’ However, notice that this reading doesn’t rule out that we can partially understand finite modes aside from the infinite chain of causes that produced them.
40Michael Della Rocca makes a similar argument for the acosmist conclusion that finite modes are unintelligible for Spinoza (2012: 163). Although there is no space to discuss Della Rocca’s ingenious challenge here in full detail, I think the perspectivalist reading of composition can avoid some of the devastating consequences of these puzzles concerning Spinoza’s overall project in the Ethics.
41See my discussion of Ep.12/IV:60–61 and 1p15s/II:59 in §3. See also Ep.30/IV:166/10–15. Cf. Newlands (2018: 158). On Newlands’s interpretation, we should treat Spinoza’s comments in Ep.30 as claiming that the narrow conceptions of things are merely morally disadvantageous. This may be right in the particular context of Ep.30, but it is hard to see Spinoza making a moral claim instead of an epistemic claim in Ep.12 and 1p15s.
42However, Ghislain Guigon argues on the basis of this clue—and Spinoza’s early discussions of beings of reason—that mereological definitions are (i) neither true nor false, and (ii) only useful in imagination (2012: 196). And Rosenthal (2019) argues that Spinoza considered beings of reason—including parts and wholes—as cognitive tools for organizing sense-experience, which get epistemic justification in terms of practical utility as opposed to theoretical truth. Although my interpretation has a very similar upshot to these readings, and I also agree that the textual reasons (especially in the CM) point in this direction, I think they are not expressing Spinoza’s views in the Ethics (especially starting from Part 2) and Ep.32. In these later works, he clearly takes mereological definitions to be true and to belong to reasoning as opposed to imagination. What is more, since Spinoza is using the geometric method, it is hard to see how he could use mereological definitions in later demonstrations if they are neither true nor false. (For a similar worry against reading Spinoza’s mereology as only addressing ‘appearance’, see Sacksteder 1977: 149).
43See, e.g., 2p38–40. In an often overlooked contribution, Sacksteder also puts emphasis on the idea that common notions such as motion and rest undergird Spinoza’s mereology (1985: 402). It is worth noting that motion and rest applies to modes of extension only, which doesn’t explain Spinoza’s mereology concerning minds, even though Spinoza seems to tie mental parts and wholes to their corresponding objects in extension (see e.g., 2p11c; Ep.32/IV:174a). Cf. Barbone (2002: 104–5). Barbone—citing an observation by Gueroult (1974: 17)—argues that Spinoza considers political states as quasi-individuals on the assumption that they don’t have a corresponding single mind, which he takes to be a necessary condition for composition.
44In fact, I agree with Bennett (1984: 232), Garrett (1994: 82–87), and Peterman (2014) that Spinoza simply did not provide us enough information to figure out how, e.g., motion and rest, or other common notions of extension are supposed to work.
45However, I don’t think that thereby we shouldn’t speculate about where Spinoza would stand on these issues. For a great discussion of Spinoza’s mereology through the lens of van Inwagen’s ‘Special Composition Question’ (1990: 30–31), see Newlands (2018: 137–38).
46Earlier versions of this essay were presented at the History of Modern Philosophy Research Group at the University of Toronto, the Collegium Spinozanum II at the University of Groningen, and the Society for Early Modern Philosophy at Yale. Thanks to everyone who attended those events for your questions and objections. Thanks also to Karolina Hübner, Marleen Rozemond, Michael Della Rocca, Allison Peterman, Nick Stang, Ken Winkler, and two anonymous referees for their invaluable comments.
The author has no competing interests to declare.
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