[Final version to appear in the Blackwell Companion to Spinoza, Yitzhak Melamed, ed. Please ask me before quoting this version.] Kant and Spinoza Colin Marshall University of Washington Kant makes a striking reference to Spinoza in the 1788 Critique of Practical Reason. If, Kant claims, his own idealism about space and time "is not adopted, nothing remains but Spinozism, in which space and time are essential determinations of the original being itself, while the things dependent upon it (ourselves, therefore, included) are not substances but merely accidents inhering in it" (2nd Critique 5:102; Kant 1996, 221).1 That is, Kant states that the best alternative to his own metaphysical system is Spinoza's radical substance monism, according to which everything inheres in a single substance. This passage motivates two questions: (a) how deeply did Kant engage with Spinoza's philosophy and (b) how close are their philosophical views? I believe that the answer to (a) is, disappointingly: "not much." Despite that, I believe that the answer to (b) is: "on some points, surprisingly close." Together, these answers raise further historical questions about why Kant and Spinoza's views sometimes converge and further philosophical questions about those views' plausibility. Spinoza and Kant were proudly independent thinkers, so any points of nearconvergence between them deserve philosophical attention. I begin by investigating whether Kant directly concerned himself with Spinoza, focusing on Omri Boehm's recent study (the most extensive case in the literature for thinking that Kant was deeply concerned with Spinoza). I argue that Boehm's case is not convincing. I then turn to identifying two philosophically interesting points on which Spinoza's and Kant's views come surprisingly close: (1) their arguments for the limitations of our sensory knowledge and (2) their arguments for the timelessness of the mind.2 1 All references to the first Critique will use the standard A/B format. References to Kant's other works will be to volume and page number of the Academy edition (Kant 1900), with abbreviated titles. All translations are from the Cambridge edition of Kant's works. 2 I focus on metaphysical issues, since most of Kant's references to Spinoza concern metaphysics (Kant considers the epistemology of "Lichtenberg's Spinoza" in the Opus Postumum (e.g., 22:54-5)). I do not discuss Kant's references to Spinoza in the third Critique (e.g., 5:393-4), since these obviously betray Kant's ignorance of Spinoza's actual views on teleology (cf. E1App.). See Marshall 2010 for an additional 2 My discussion has a limited scope. In 1785, Friedrich Heinrich Jacobi ignited a heated debate by arguing that Spinozist pantheism was the inevitable and absurd result of philosophy, with special focus on Kant.3 After 1785, Kant could not avoid discussion of Spinozism, and the above remark from the second Critique must be understood in this context. My concern here is with Kant's relation to Spinoza's actual philosophy, however, not the broadly Spinozist themes of the Pantheism Controversy. Moreover, Kant established the main tenets of his theoretical and practical philosophy before 1785. Aside from the above passage from the second Critique, I therefore bracket most of Kant's post-1785 references to Spinozism. 1. Was Kant Engaged with Spinoza's Philosophy? Omri Boehm has recently argued that Kant closely engaged with Spinoza's claims and arguments.4 Boehm focuses on Kant's first Critique, specifically, the Transcendental Dialectic, in which Kant criticizes traditional, 'dogmatic' metaphysics. Kant's scattered references to Spinoza justify this textual focus. When Kant discusses Spinoza up through 1785, he is almost always concerned with Spinoza's substance monism. So if Kant were genuinely engaged with Spinoza's philosophy, it would probably be in his criticisms of dogmatic metaphysics. The first Critique (first published in 1781) is Kant's main presentation of those criticisms. The Dialectic offers both a general account of dogmatic metaphysics and discussions of specific metaphysical issues: the soul (the 'Paralogisms'), the 'world whole' (the 'Antinomies'), and God (the 'Ideal'). In my view, Boehm's most compelling arguments concern Kant's general account of dogmatic metaphysics and the Ideal.5 In this section, I discuss each of those, before returning to the striking passage from the second Critique. potential point of metaphysical overlap between the two and Marshall 2017 for comparisons of their metaethical views. Spinoza's argument in E4p72d has struck some commentators as Kantian, but Cooney (Unpublished) compellingly argues that it is not. Israel 2011 offers an influential discussion of Spinoza's and Kant's political philosophies. 3 For three more detailed discussions, see Beiser 1987, Franks 2005, and Lord 2011. 4 In his Introduction, Boehm implies that that Kant "read Spinoza" and "consider[ed] the Ethics worthy of a philosophical reply" (Boehm 2014, 1). Boehm also emphasizes that Kant had access to Spinoza's views via works like Pierre Bayle's 1697 Dictionnaire, and suggestively states that "it would be tempting, for every philosophically inclined thinker, to read Spinoza for themselves" (Boehm 2014, 2). Elsewhere, however, Boehm grants that Kant was concerned with a Spinozism which "may not correspond exactly to Spinoza's own system" (Boehm 2014, 147). Given my purposes, I take Boehm's intended conclusion to be the one suggested by his Introduction. 5 Boehm argues that Kant's First and Third Antinomies concern Spinoza's views. As Boehm himself allows, though, if the Antinomies are meant to address Spinoza, they reveal significantly misunderstandings (Boehm 2014, 81, 91, 131). Moreover, Kant suggests that the Antinomies reflect general metaphysical tendencies, not any particular metaphysician's views (see A411/B438, A46572/B493-500). 3 1.1. Fundamental Principles of Metaphysics Boehm claims that "Kant's critique of reason [is] a critique of the Principle of Sufficient Reason; specifically, of the Spinozist (rather than Leibnizian) application and the Spinozist consequences of that principle" (Boehm 2014, 6-7). The Principle of Sufficient Reason (PSR), on Spinoza's best-known formulation, states that "[f]or each thing there must be assigned a cause, or reason, both for its existence and for its nonexistence" (E1p11d). This strong principle is central to Spinoza's metaphysics.6 Therefore, if Kant were engaged with Spinoza's philosophy, we would expect that his general characterization of metaphysics would hinge on the PSR. An examination of the text suggests otherwise, however. Dogmatic metaphysics, Kant holds, arises from an illusion in which we confuse a legitimate subjective demand of reason with an objective principle, thereby wrongly taking ourselves to have a priori metaphysical insight. The subjective demand is "to find the unconditioned for conditioned cognitions of the understanding" (A307/B364). This is a demand to discover all the explanatory conditions for the objects we experience, such as the causes of events and the substrata of properties. The demand is ontologically neutral – as an imperative, it does not entail that any conditions exist. However, Kant claims that the demand acquires psychological force only when we assume "that when the conditioned is given [i.e., exists], then so is the whole series of conditions... which is itself unconditioned, also given" (A307-8/B364). Dogmatic metaphysics arises then, on Kant's view, because we confuse a rational need for complete explanations with an a priori insight into there being rationally satisfying endpoints of explanations. Boehm claims that the subjective demand and the objective principle are "nothing but formulations of the PSR" (Boehm 2014, 51). Kant suggests that connection elsewhere 7 and, in a related unpublished note, declares that "Spinozism is the true consequence of dogmatic metaphysics" (R6050, 18:436). So, Boehm suggests, there are strong textual reasons for thinking that Kant was specifically concerned with Spinoza in the Dialectic's general account of dogmatic metaphysics. However, Kant's objective principle, which he claims is the source of dogmatic metaphysics, is much weaker than Spinoza's PSR. Consider again Spinoza's statement of the PSR in E1p11d: "[f]or each thing there must be assigned a cause, or reason, both for its existence and for its nonexistence" (E1p11d). Spinoza's principle applies to all things, whereas 6 For an influential PSR-focused reading of Spinoza, see Della Rocca 2008. 7 "On a discovery" (8:193-8). 4 Kant's objective principle claims only that conditioned (dependent) things have explanatory bases. Kant's principle seems undeniable: surely, if something dependent exists, then so does everything on which it depends. That apparent undeniability is why Kant claims that metaphysical illusion "cannot be avoided at all" (A297/B354). By contrast, Spinoza's PSR would be denied by anyone who thinks there are brute facts about what exists. Kant thinks the objective principle yields radical metaphysical conclusions only in conjunction with further claims about specific conditioning relations. These further claims concern the representation "I think" (see A341/B399), the parts of space and time (see A412/B439), causation (see A414/B441-2), and contingency and necessity (see A415/B442, cf. A571-6/B599-605). For example, Kant holds that we are drawn towards the metaphysical conclusion that infinitely many times have passed by the objective principle together with the claim that every time depends on a preceding time. On Kant's account, therefore, traditional metaphysics does not hinge on a strong PSR, but instead on a relatively weak principle about conditions and quite strong principles about particular dependence relations. The picture of dogmatic metaphysics that Kant offers is therefore quite un-Spinozistic. This is evidence that Spinoza was not central to Kant's understanding of traditional metaphysics, and so that Kant was not seriously engaged with Spinoza's views – even though he surely took his general characterization of rationalist metaphysical tendencies to apply to Spinoza. A further piece of evidence for non-engagement is the fact that God appears late in Kant's account of dogmatic metaphysics (after, e.g., immortality), whereas God is central to Spinoza's metaphysics. This brings us to our next topic. 1.2. Kant's Transcendental Ideal and Spinoza's God In the Ideal of Reason chapter, Kant claims that one inevitable idea of reason is that of a most real being (God), which "contains as it were the entire storehouse of material from which all possible predicates of things can be taken" (A575/B603). Such a being thereby "grounds every thing as the condition of its thoroughgoing determination" (A573/B601), that is, of everything's being such that "of every two contradictorily opposed predicates only one can apply to it" (A571/B599). The rough idea is that, for every property P, any real thing is either P or not-P, and that this principle seems meaningful only if some entity generates or supports a non-empty set of properties. In the Critique, Kant denies we can prove this being's existence, though he gives the idea of it an important regulative role in our thought (this is a retreat from Kant's 1763 Only Possible Argument in Support of the Existence of a God, where he took similar considerations to demonstrate God's existence). The Critique, then, holds up the idea of an 5 ultimate ground of possibility as rationally valuable. This idea is at least broadly Spinozistic, since Spinoza makes God the explanatory ground of everything. Boehm claims that the mature Kant therefore endorses a "regulative Spinozism" (Boehm 2014, 58). Others besides Boehm have seen a connection to Spinoza here. As Boehm notes, Jacobi claimed he realized that all philosophy leads to Spinoza based on Kant's Only Possible Argument (Boehm 2014, 18). Recently, Andrew Chignell sparked a debate about whether Kant's 1763 proof implies, a la Spinoza, that everything is a property of God.8 There is therefore at least some similarity between Spinoza and Kant on this topic. My current concern, though, is whether this similarity indicates that Kant meaningfully engaged with Spinoza's philosophy. By comparison: Kant also adopts Plato's talk of ideas in the Dialectic, mentioning Plato explicitly (see A313-27/B370-4), but his engagement with Plato's actual views there is minimal. Similarly, there are at least three reasons to think that Kant's engagement with Spinoza on this point was at most superficial. First: Kant's focus is on how one arrives at the idea of God from the given possibility of finite things. In 1763, he saw this as a proof for God's existence, whereas in 1781 he saw it instead as the inevitable course of reason under the influence of metaphysical illusion. Spinoza, however, does not define God in terms of possibilities, and his proofs for God's existence make no appeal to the given possibility of finite things (see E1d6 and E1p11d). To be sure, Kant took himself to be identifying an underlying source for earlier rationalists' ideas of God, but his account does not seem sensitive to Spinoza's actual views.9 Second: Kant's interest in the source of possibility depends on his view that finite things are contingent. He shows no interest in necessitarian views like Spinoza's, according to which nothing is contingent (E1p29). Yet Spinoza's necessitarianism is the most conspicuous feature of his modal metaphysics. If Kant were seriously engaged with Spinoza on this point, we would expect him to engage with necessitarianism. Yet he does not. Third: Almost all of Kant's early explicit references to Spinoza concern substance monism. So if the Ideal were concerned with Spinoza, one would expect a significant discussion of monism. Taking God to be the ground of possibility does not obviously push in the direction of substance monism. Consider, for example, Descartes' view, on which God makes space possible and creates genuine spatial substances. If Kant were engaging with Spinoza on this point, then we would expect him to contrast substance monism with views like Descartes'. But Kant does not. 8 See (e.g.) Chignell 2014, Hoffer 2016. 9 Kant mentions Spinoza in the Only Possible Argument (2:74), but only in an off-hand example. 6 Kant's discussion of God as the ground of possibility does not, therefore, indicate that he was meaningfully engaged with Spinoza's actual philosophy. 1.3. Why is Spinozism the Alternative to Kant's Idealism? Why, then, does Kant claim that if the "ideality of space are time is not adopted, nothing remains but Spinozism"?10 This discussion occurs three years after the start of the Pantheism Controversy and talks of Spinozism generally, but perhaps a close examination of the passage will reveal some genuine engagement with Spinoza. Kant makes the remark while arguing that only his idealism about space and time makes it "possible to affirm freedom without compromising the natural mechanism of actions" (2nd Critique 5:102). So why does Kant think that Spinozism is the best alternative to his idealism?11 The main non-ideal alternative to Spinozism that Kant mentions is Moses Mendelssohn's view that space and time are "conditions necessarily belonging only to the existence of finite and derived beings but not to that of the original being" (2nd Critique 5:101). Mendelssohn clearly takes some finite beings to be substances. Hence, Kant is focused on two claims: (a) God is spatiotemporal. (b) Some finite beings are substances. Mendelssohn denies (a) but affirms (b), while the Spinozist affirms (a) but denies (b).12 Kant seems to think are the two best realist views.13 10 This privileging of Spinozism is especially surprising in light of Kant's claims (Lectures on Religion, 28:1052) that Spinoza's monism leads to "crude contradictions" implying that either I am either God (which "contradicts my dependency") or an accident (which "contradicts my concept of my I"). 11 Brewer and Watkins 2012, Massimi 2017, and Messina (Unpublished) offer alternative approaches to this passage from what I suggest below, while giving useful historical background (none find Kant meaningfully engaging with Spinoza). All three focus on freedom, whereas I do not think freedom is crucial to Kant's privileging of Spinozism. Massimi takes Kant to just borrow a use of "Spinozism" from Alexander Baumgarten. 12 Spinoza himself, though, states that God's existence "cannot be explained by duration or time" (E1d8). 13 What would be worse about accepting both (a) (or a merely temporal version of (a)) together with (b)? At 5:101, Kant implies that such a view yields an unacceptable fatalism, but the same is supposedly true of any realist view (see Bxxvii-xxix). Perhaps Kant's implicit thought is that accepting (a) and (b) implausibly posits God as just one (spatio-)temporal substance among others, whereas Mendelssohn's and Spinoza's views would not. For somewhat related points, see Brewer and Watkins 2012, 168-9, 185 and Massimi 2017, 77. 7 Kant provides two reasons for preferring Spinozism over Mendelssohnianism. The first is that "I do not see how [the Mendelssohnians] would justify themselves in making such a distinction" (2nd Critique 5:101), that is, in limiting spatiotemporality to finite things in themselves. Kant does not elaborate on why this distinction or limitation would be problematic. After all, couldn't God's infinitude and perfection provide some reason for differing from finite, imperfect creatures in spatiotemporality? One possibility is that Kant is assuming some general metaphysical continuity principle here, such as Spinoza's claim that "the laws and rules of Nature, accord to which all things happen... are always and everywhere the same" (E3Preface, cf. A657-8/B685-6).14 Another possibility is suggested by Kant's discussion of space and time in the B edition of the first Critique. Kant asks "with what right" a realist can deny that space and time condition God's existence, given that space and time "as conditions of all existence in general... would also have to be conditions of the existence of God" (B71). Strictly speaking, the latter claim is a mere tautology, but perhaps Kant's underlying thought is that if one thing in itself is spatiotemporal, they all must be, because space and time are inherently general. This is an interesting principle, but not one Spinoza endorses. Kant's second reason for preferring Spinoza's view is that Mendelssohn's view "is contradictory to the concept of [God's] infinity and independence" (2nd Critique 5:101). On Mendelssohn's view, while God causes the existence of finite things, he "cannot be the cause of time (or space) itself," because "this must be presupposed as a necessary a priori condition of the existence of things" (2nd Critique 5:101). Hence, on Mendelssohn's view, God's causality would be conditioned by space and time, contradicting his independence. Why couldn't a Mendelssohnian respond here that God (not himself being spatiotemporal) created space and time before creating finite things, and so was not conditioned by them in a way that threatened his independence? Kant's talk of a priori conditions might suggest that his answer would be that Mendelssohnians could not account for our a priori cognition of space and time. However, Kant holds that only his idealist view can secure that cognition (see, e.g., Prolegomena 4:283-4), so Spinozist realism would supposedly do no better than Mendelssohnian realism here. The first Critique again provides a helpful hint. There, Kant claims that it would be absurd to posit "two infinite things that are neither substances nor anything really inhering in substances" (B70-1, see also A39/B56). Kant does not explain why this would be absurd – he does not bring in epistemological considerations here, nor does he seem to be appealing to the PSR (contra Boehm 2014, 80-4). What is important, however, is 14 Drawing on A458/B486, Boehm proposes that Kant's underlying principle here is that whatever grounds things of a type (e.g., spatiotemporal things) must be of the same type (Boehm 2014, 127-29). Yet Kant cannot endorse that principle in full generality, since he takes non-spatiotemporal noumena to ground spatiotemporal phenomena (e.g., A379-80, Prolegomena 5:314-15). 8 that this presumed absurdity would only be found in Mendelssohn's view.15 For on Spinoza's view, space (or, at least, extension) is an attribute of God, and time (duration) arises in God's modes (See E1d6, E1p15s, E2d5). This reading fits with a passage from Kant's lectures, where he states that "If I assume space to be a being in itself, then Spinozism is irrefutable, i.e., the parts of the world are parts of the divinity. Space is the divinity; it is united, all-present; nothing can be thought outside of it; everything is in it" (Metaphysics L2 28:567).16 On most points, this argument is far from Spinoza's views, not least since Spinoza treats space (extension) and time quite differently. Moreover, Spinoza does not obviously have a notion that aligns with Kant's notion of space: physical bodies, for Spinoza, are mere modes of extension, whereas Kant would deny that physical bodies are modes of space (see, e.g., Metaphysical Foundations 4:497). Yet there is one point on which Kant's argument does resemble Spinoza's views: the claim that it would be absurd for anything to exist without being a substance or inhering in a substance.17 The first axiom of the Ethics is that "Whatever is, is either in itself or in another" (E1a1), implying (in conjunction with E1d3) that all things are substances or inhere in substances. Spinoza is not the only philosopher who accepts this view, however – it is widespread in the Aristotelian and rationalist traditions. Hence, Kant's privileging of Spinozism among realist views seems generally detached from Spinoza's actual thought. His discussion of Spinozism in the second Critique rests on broad (and misleading) characterizations of Spinoza's philosophy in the writings of Jacobi and others. 2. Points of Convergence Setting aside questions of engagement, my concern in this section is with points at which Kant's and Spinoza's philosophy converged or came close to converging. We have already discussed one such point: both think that substance monism is more plausible than other traditional metaphysical views. I now consider two further philosophically interesting points which I think deserve further attention, one about the limits of sensory knowledge, and one about the timelessness of the mind. 15 Brewer and Watkins suggest, alternatively, that Kant holds that God could not create time because doing so would require that God represent time, which would in turn require that God have a sensible (passive) faculty of representation (Brewer and Watkins 2012, 171, though cf. Marshall 2018). 16 This passage arguably indicates limited familiarity with Spinoza's metaphysics, since Spinoza denies that God has parts (see E1p12-13, E1p15s). 17 If we can set aside the (non-trivial) question about Spinoza's extension vs. Kant's space, then (as James Messina has helped me appreciate) both would presumably agree that the whole of space is prior to its parts (see E1p15s, A24-5/B39). 9 2.1. Short arguments to humility about sensory knowledge Kant famously claims that we have cognition (Erkenntnis) only of appearances, not of things in themselves. Call this claim 'Humility.' Humility has been glossed as a claim about knowledge, but recent interpreters have shown that Kant's notion of cognition is importantly different from contemporary notions of knowledge.18 Cognitions, for Kant, are conceptuallydetermined representations of objects that are given to us in intuition (roughly: conceptualized perceptions). There is ongoing debate about why Kant accepts Humility. His best-known arguments for it appeal to epistemological considerations about space and time (e.g., Prolegomena 4:281-82). Roughly, Kant argues that the only explanation for our a priori cognition of space and time is that they are mere forms of our sensory representations. Hence, since all our sensory experience is spatiotemporal, we are never directly presented with features of things in themselves. There is no obvious analogue of this epistemological argument in Spinoza. Elsewhere, however, Kant seems to reach Humility without appealing to a priori cognition of space and time. These passages appear to involve what Karl Ameriks has (pejoratively) called "short arguments to idealism."19 For example, in the Prolegomena Kant writes that: if we view the objects of the senses as mere appearances, as is fitting, then we thereby admit... that a thing in itself underlies them, although we are not acquainted with this thing as it may be constituted in itself, but only with its appearance, i.e., with the way in which our senses are affected by this unknown something. (Prolegomena 4:314-15) Similarly, in the Groundwork: No subtle reflection is required to make the following remark... all representations which come to us involuntarily (as do those of the senses) enable us to cognize objects only as they affect us and we remain ignorant of what they may be in themselves (Groundwork 4:450-51). 18 E.g., Watkins and Willaschek 2017. 19 See Ameriks 2003, 135. Ameriks denies that Kant relies on short arguments. See Langton 1998 for an influential short argument interpretation (unlike what I suggest below, Langton appeals to relationality, not passivity). 10 In these passages, Kant seems to infer Humility from passivity, that is, the fact that our sensory representations result from our being affected. This inference is not obviously valid. Why couldn't God, for instance, affect us to produce an accurate representation of some thing in itself? Bracketing questions of validity for now, these short arguments to Humility closely resemble a central argument from Part 2 of Spinoza's Ethics. At E2p16 (drawing on A1'' after E2p13), Spinoza claims that "[t]he idea of any mode in which the human body is affected by external bodies must involve the nature of the human body and at the same time the nature of the external body." From this, he infers that "the ideas which we have of external bodies indicate the condition of our own body more than the nature of external bodies" (E2p16c2) and that "[t]he idea of any affection of the human body does not involve adequate knowledge of an external body" (E2p25). On Spinoza's view, then, any representation that results from our being affected must involve both our own nature and the nature of an external thing. This is arguably based on Spinoza's view that inherence (being 'in us') involves explanatory dependence (being 'conceived through' – see E1d5). Hence, we cannot have any representation in us that purely reflects the nature of some external thing. This may help address the worry about the validity of Kant's short arguments: the nature of inherence makes it metaphysically impossible for a representation to be in us that does not involve our own nature.20 Surprisingly, Kant seems to say exactly this in his early metaphysics lectures, well before he conceived his mature arguments for Humility: Each subject in which an accident inheres must itself contain a ground of its inherence. For if, e.g., God could produce a thought in a soul merely by himself: then God, but not a soul, would have the thought... Thus for the inherence of an accident in A its own power is required (Metaphysics Herder, 28:52) There is, therefore, a surprising convergence between Spinoza on Kant in their short arguments for why sensory representations do not present us with unfiltered views of external things. One might expect Spinoza's and Kant's epistemological similarities to stop here. Spinoza thinks we have adequate ideas of God's essence (2p46), while Kant denies that we have theoretical insight into the nature of any thing in itself. They would also count quite different 20 This does not fully answer the objection, though. Kant works with a sharp vehicle/content distinction, so our nature might be involved only in the vehicle of the representation, not its content. Spinoza arguably rejects a sharp a vehicle/content distinction (see E2p49s and §2.2 below), and so may be on stronger ground here. 11 things as being 'external' to us. Surprisingly, however, both seem drawn to a positive line of argument about the timelessness of the mind. 2.2. Representational Content and the Timelessness of the Mind Shortly after arguing for Humility in the Groundwork, Kant claims that "a human being really finds in himself a capacity by which he distinguishes himself from all other things... reason," and that he "must regard himself as intelligence (hence not from the side of his lower powers) as belonging not to the world of sense" (Groundwork 4:452). Since Kant holds that time exists only in the world of sense (see A33-5/B49-51), his claims imply that part of our mind is timeless, making room for some form of immortality (2nd Critique 5:122). Spinoza reaches a similar conclusion in the Ethics, claiming that "[t]he human Mind cannot be absolutely destroyed with the Body, but something of it remains which is eternal" (E5p23). Eternity, for Spinoza, "cannot be explained by duration or time, even if the duration is conceived to be without beginning or end" (E1d8). Hence both Spinoza and Kant argue that one part or aspect of the mind is timeless. What is most striking, however, is that both Spinoza and Kant argue for this claim based on the content of our intellectual representations.21 The details of these arguments, which involve different assumptions, reveal subtle and important aspects of their respective views. Kant claims that reason cannot belong to the temporal, sensory realm because reason, "as pure self-activity ... shows in what we call 'ideas' a spontaneity so pure that it thereby goes far beyond anything that sensibility can ever afford it" (Groundwork 4:452). Ideas, for Kant, are "concepts of pure reason" that "consider all experiential cognition through an absolute totality of conditions" (A327/B383-4). Ideas thus represent absolute totalities, which are too 'big' for sensibility to represent, since sensory representation "gives us no true universality" (A1). Kant makes a similar argument in the third Critique, focusing on infinity: "even to be able to think the given infinite without contradiction requires a faculty in the human mind that is itself supersensible" (3rd Critique 2:254-5). Only a truly self-active or spontaneous faculty could entertain such content, Kant holds. Yet the temporal world, on his view, is causally determined, leaving no room for spontaneity (see, e.g., A534/B562). Hence, some aspect of the mind must be timeless.22 21 Plato, from whom Kant borrows the term 'idea' (A313-17/B370-74), makes a similar argument in the Phaedo (see also Aristotle, De Anima 2.12 and 3.4). 22 Though many contemporary Kant scholars read these passages as making metaphysical claims, some deny they have metaphysical import (see, e.g., Allison 1990). 12 Spinoza's official argument for the timelessness of the mind (E5p23d) appeals to his doctrines of the eternity of the body's essence, the parallel between bodies and ideas, and his identification of the human mind with God's idea of the human body. These last two doctrines are highly idiosyncratic, so Spinoza's official argument is far removed from Kant's views. However, in a scholium, Spinoza appears to offer a second argument: we feel and know by experience that we are eternal. For the mind feels those things that it conceives in understanding no less than those it has in the memory. For the eyes of the mind, by which it sees and observes things, are the demonstrations themselves. (E5p23s) Spinoza does not call this argument a demonstration, so perhaps we should not put too much weight on it. Even so, the passage raises two questions. First, in what sense do we 'feel' or 'see' in demonstrations? Second, why should seeing things in demonstrations provide knowledge of the eternity of our mind? A contrast with Kant may be helpful. Unlike Kant, Spinoza does not deny that sensory representations can have 'big' contents; he holds that every idea involves adequate knowledge of God's infinite essence (E2p45-46). In addition, while Kant appeals merely to ideas of totalities and infinities, Spinoza appeals to demonstrations. A demonstration may involve ideas (in Kant's sense), but it also would seem to require truth, that is, that the ideas correspond to reality. These points are connected, for Spinoza holds that, unlike sensory knowledge, demonstrations teach us "to distinguish the true from the false" (E2p42). Demonstrations, for Spinoza, concern eternal truths. In E5p23s, he implies that all demonstrations let us experience our eternality. Yet how, as Spinoza says, is there an experience of our eternality in our apprehension of a demonstration? That is, why should a representation of eternal truths come with an experience of oneself being eternal? A principle from Spinoza's early work, the Short Treatise, may be in play here. There, Spinoza claims that "whatever we find in ourselves has more power over us than anything which comes from outside" (KV II, 21; cf. 4p9, 4p29).23 The underlying thought, then, may be that in demonstrations, eternal truths have a certain sort of psychological power over us, a power whereby they teach us how to distinguish truth from falsity. For demonstrations to have that power, though, the objects of the representations (the eternal truths) must be in us. Yet, in line with the principle about inherence mentioned in §2.1, it seems that something eternal can be in us (in the relevant sense) only if some part or aspect of ourselves is eternal. 23 For further discussion, see Marshall 2015. 13 This line of thought differs from Kant's argument. However, Kant also seems to think that a psychologically powerful representation must have a metaphysically proximate object. For example, in the first Critique, one of his arguments for space and time being in us (as forms of our sensibility) appeals to their power as representations, e.g., "[o]ne can never represent that there is no space" (A24/B38). In the second Critique, Kant talks of how the moral law "forces itself upon us", and seems to take it as a corollary of this that the source of the moral law is in us, as our faculty of reason: "[p]ure reason... gives (to the human being) a universal law that is the moral law" (2nd Critique 5:31). Perhaps the basic thought here is that, if you can't shake the representation of some object, then the object must somehow be in you, forcing you to represent it. Kant and Spinoza seem to agree on this point, though perhaps only Spinoza applies it to content-based arguments for the timelessness of the mind. Conclusion I have argued that Kant was not meaningfully engaged with Spinoza's actual philosophy. Despite that, and despite differences in their understandings of fundamental metaphysics, Spinoza and Kant's philosophies come close at some surprising points. There are historical and philosophical questions about why this is. 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