Introduction
Aristotle gives a theory of animal locomotion in several different places in his corpus. In Physics VIII, self-movers are said to initiate locomotion, rather than qualitative and quantitative change.1 Already there, in his lengthy and abstract discussion of motion, Aristotle identifies animals as the paradigmatic self-movers. In VIII 5, whatever his broader aims in the last book of Physics might be, Aristotle’s discussion serves to precisely formulate self-motion.2 This chapter also includes a famous ‘tripartite scheme’ (3S), in which there is an unmoved mover, an instrument of motion, and finally, a moved thing, which need not move anything further (Physics VIII 5 256b14–20). In De Anima III 10, Aristotle seemingly applies this scheme to animal locomotion with more circumspection, explaining that the first element is in fact composed of the faculty of desire and its object, the second is some sort of bodily instrument, and the third is the animal itself—at least as most read the passage (DA III 10 433b13–433b18). This tripartite scheme is referenced again in condensed form in de Motu Animalium.3 How the DA and Physics versions of the 3S precisely relate to each other has been disputed. Some (Shields 2016: 362) hold that the developed DA scheme aligns unproblematically with the Physics one, while others propose (Polansky 2007: 521–522; Rapp 2020a: 276–284), contrarily, that the DA scheme includes one additional stage.
One reason I think this concern has arisen is that commentators have focused solely on aligning the DA version of the tripartite scheme with that appearing in Physics VIII 5 256b14–20, without attending to the broader context of that passage. Neglecting this context leads to several difficulties about the scheme’s appearance in DA III 10, outlined in §3 below. I will argue that, within the context of Physics VIII, Aristotle’s tripartite scheme is founded on a more basic principle, the Separability Thesis (ST), which states that every self-mover (i.e., animal) has a part initiating motion and a part that is moved. Once the 3S is understood simply as an application of ST, I argue that the troubling questions about the scheme’s use in DA are alleviated. My strategy is roundabout. I begin by presenting in schematic form the tripartite scheme of DA III 10, before outlining the motivating difficulties. Then I present the tripartite scheme of Physics VIII 5. Next, in several stages, mostly predicated on contextual considerations of Physics VIII 4–5 and Aristotle’s ‘alphabet analogy,’ I seek to establish that the tripartite scheme is derivative upon the Separability Thesis in the context of explaining self-motion. Finally, I suggest that my interpretation offers a novel way of answering a common worry about the unity of self-movers.
The Tripartite Scheme of De Anima III 10
Near the end of DA III 10, Aristotle deploys general principles of kinetics to give his specific theory of animal locomotion. He writes:
Since there are three things, first, what initiates motion [ἓν μὲν τὸ κινοῦν], second, that by which it initiates motion [ᾧ κινɛῖ], and further, third, what is moved, and that which initiates motion is twofold [τὸ δὲ κινοῦν διττόν], in the one instance being unmoved and in the other initiating motion while being moved, there is: something unmoved, the good concerned with what can be done [τὸ πρακτὸν ἀγαθόν]; something initiating motion while being moved, the faculty of desire [τὸ ὀρɛκτικόν] (for what is moved is moved insofar as it is desiring, and desire, inasmuch as it is an actuality, is a kind of motion); and what is moved, the animal [τὸ ζῷον] (433b13–433b18).4
Initially, the scheme has three stages as announced. But there is a qualification: ‘that which initiates motion is twofold.’ Most recent commentators agree that this qualification refers to a subdivision within the first stage of the tripartite scheme, essentially making the DA III 10 version of the scheme quadripartite (Laks 2020: 480–1; Rapp 2020a: 277–282). An alternative view holds that the qualification is an explication of the first and second stages of the scheme, rather than an additional subdivision (Shields 2016: 362). One key outcome of the second reading is that it maintains a three-part picture and thus makes DA III 10 more readily congruous with the scheme of Physics VIII 5. Nevertheless, I side with the first interpretation, which seems the implication of reiterating κινοῦν in the phrase τὸ δὲ κινοῦν διττόν in reference to the earlier description of the first stage, ἓν μὲν τὸ κινοῦν.5 This interpretation means that Aristotle’s use of the tripartite scheme in DA does not cleanly align with that of Physics.
Before attempting to map out which parts of the locomoting animal are meant to correspond to each stage, it will be helpful to provide a general diagrammatic outline. I take inspiration from Rapp’s notation (2020a: 277), attaching bolded markers to each stage:6
What initiates motion (τὸ κινοῦν) (M)
What initiates motion as something unmoved (ἀκίνητον) (UM)
What initiates motion as something moved (κινοῦν καὶ κινούμɛνον) (MM)
That by means of which it initiates motion—the instrument of motion (ᾧ κινɛῖ) (IM)
What is moved, i.e., the moved entity (τὸ κινούμɛνον) (ME)
Though there are five lines in the scheme, this is only because stage one (M) has been divided into the unmoved (UM) and moved movers (MM), creating a total of four steps.
Given the aims of De Anima, Aristotle is not interested in a purely abstract account, and so specifies the aspect of the animal’s physiology or psychology at each step. Thus, he tells us that the unmoved mover (UM) is the practical good (τὸ πρακτὸν ἀγαθόν), whereas the moved mover (MM) is the faculty of desire (τὸ ὀρɛκτικόν). At first, he appears to skip over the instrument of motion (IM) ‘by which’ the first stage moves,7 but he does state that the moved entity (ME) is the animal (τὸ ζῷον). In the following lines (433b19–21), he explains that ‘the instrument by which desire initiates motion [ᾧ δὲ κινɛῖ ὀργάνῳ]’ is ‘bodily’ (σωματικόν) and that it will be examined more thoroughly ‘among the functions common to body and soul.’8 Here it is reasonable to suppose that the datives in ᾧ δὲ κινɛῖ ὀργάνῳ recall the similar use in the tripartite scheme passage, ᾧ κινɛῖ. Omitting the umbrella term for the first two stages (M), we can reconstruct the fourfold scheme in more detail:
The practical good [object of desire] (UM)
The faculty of desire (MM)
The bodily instrument ‘by which’ desire moves (IM)
The animal (ME)
The practical good can be equated with the object of desire because of remarks earlier in the chapter (433a15–16, a27–29). On its face, this completed scheme has several troubling elements. Firstly, there is a fundamental internal interpretive question about the relationship between (UM) and (MM). What kind of motion does the faculty of desire have, especially if we understand it as a soul-faculty, which famously (cf. DA I 3 405b31–406a2) is not supposed to be able to undergo motion (κίνησις)? Although fully answering the question is beyond the scope of this paper, there are two main strategies to solve the problem: (1) those who understand desire as a set of thermic alterations and not as a bona fide soul-part, so that it can unproblematically undergo standard κίνησις (Corcilius & Gregoric 2013; Corcilius 2020), and (2) those arguing that the faculty of desire, a soul-power, only undergoes a non-kinetic actualization (ἐνɛργɛῖν) by the influence of the object of desire (ὀρɛκτόν) (Hankinson 2020; Themistius 1882: I 3 17:38-39, I 3 18:33-35; (Ps-)Philoponus 1897: I 3 95.22-26, III 10 591.12-19; (Ps-)Simplicius 1882: I 3 39.8-18, III 10 302.23-28).9 I focus, however, on a second and more general issue of how to connect this scheme to its source material in Physics. What is the relationship between this (quadripartite) scheme and the general kinetic scheme that appears in Physics VIII 5 256b14–20? Most importantly, what is the context of that Physics passage and how does that bear on its use in DA?
Several Questions concerning the Tripartite Scheme in De Anima III 10
Before examining the relevant passages of Physics VIII, I want to briefly note three preeminent questions about Aristotle’s use of the tripartite scheme in DA III 10 and its relation to the version of Physics VIII 5.
(1) In context, the tripartite scheme found in Physics VIII 5 doesn’t describe animals or self-movers at all. Instead, it appears midway through an argument aiming to show that all motion starts with an unmoved (ἀκίνητον) mover (256b20, b24, b27). Yet elsewhere in VIII 5 Aristotle spills much ink to clarify the workings of self-motion, not to mention that within VIII 2–6, more generally, he frequently identifies animals as the relevant self-movers (e.g., 6 259b1–16). Faced with the choice between explicit theorizing on self-motion and the 3S, one might reasonably have expected Aristotle to import into DA aspects of discussions on self-motion rather than the 3S, in his quest to explain how the soul is responsible for locomotion (DA III 9 431a17).10 While commentators on DA are quick to note the origin of the 3S in Physics VIII 5 256b14–20, they are relatively silent on why Aristotle chose this particular kinetic scheme.11
(2) Closely related to (1), it also seems that Aristotle needs to justify integrating all three stages of the Physics 3S. For, within VIII 5, it appears that the instrument of motion (ᾧ κινɛῖ), occupying the second stage of the 3S (outlined in §4, below), is defeasible. That is, Aristotle acknowledges openly that chains of moving things can exist without the instrument (256a25–28). If that’s right, then the instrument appearing in the tripartite scheme of DA III 10 is potentially superfluous, unless a specific reason is provided for its inclusion.
(3) As an exact counterpoint to (1), one can reasonably wonder why Aristotle doesn’t instead import tools from his conceptual overview of self-movers in VIII 4–5 into DA III 10. In Physics VIII, pride of place seems granted to the Separability Thesis (ST)—the idea that self-movers must separately have an active mover and a passive moved part. If, as I will argue, ST is a more fundamental characterization of self-movers in Physics VIII than 3S, it becomes yet stranger that Aristotle does not implement ST in De Anima.
These questions thus make the central role afforded to the tripartite scheme in DA somewhat puzzling. They thus motivate the attempt to argue that ST is more foundational than the 3S. I return to these questions later, but first, in the next section, I set out the Physics tripartite scheme.
The Tripartite Scheme of Physics VIII 5
When Aristotle first articulates the tripartite scheme in Physics VIII 5 256b14–20, it appears to be about kinetics generally, not animal self-motion. Yet it seems most commentators on De Anima III 10 have simply noted the parallel between the texts without concern (Ferro 2022: 390–1, 394; Hicks 1965: 561; Laks 2020: 480 n. 23; Polansky 2007: 521–522; Rapp 2020a: 279–284; Shields 2016: 362; cf. note 11). And while it is true that the scheme outlined in Bekker lines 256b14–20 bears remarkable similarity to that in DA III 10 433b13–433b18, I argue that we risk mis-assessing the role to which Aristotle puts the scheme if we ignore the context of the Physics version.
Aristotle spends the first quarter of chapter five putting forward an argument that chains of movers must have at their start ‘something that moves itself’ (VIII 5 256a34–256b1), lest there arise an infinite regress.12 Following this argument Aristotle advances a first version of the tripartite scheme in Physics VIII. He writes:
For there must be three things—the moved [τό κινούμɛνον], the mover [τὸ κινοῦν], and the instrument of motion [τὸ ᾧ κινɛῖ]. Now the moved must be in motion, but it need not move anything else; the instrument of motion must both move something else and be itself in motion (for it changes together [συμμɛταβάλλɛι] with the moved, with which it is in contact [ἅμα] and continuous, as is the case of things that move other things locally, in which case the two things must up to a certain point be touching [ἅπτɛσθαι]); and the mover—that is to say, that which causes motion in such a manner that it is not merely the instrument of motion—must be unmoved [ἀκίνητον] (VIII 5 256b14–20).13
Using a Rapp-style diagram (cf. 2020a: 280), the stages of this first tripartite scheme can be outlined as follows:
What imparts motion as something unmoved (UM)
That by which the mover imparts movement—the instrument of motion (IM)
What is moved (ME)
At this point, the picture is supposed to be a fully generalized account of motion, with three elements. First, there is the unmoved mover. We are not yet told that in the case of animal locomotion this is, in some manner, the soul, though that is reasonable to think (cf. DA I 3 406a30; MA 6 700b9–11; Simplicius 1895: VIII 4 1208.29-31; Coren 2019a: 378; Morison 2004: 75–78; Solmsen 1971: 176–179; Waterlow 1982: 213).14 Second, there is an instrument of motion, that ‘by which’ (ᾧ κινɛῖ) this unmoved mover imparts motion. Finally, there is the thing that is moved.
On its own, the absence of a moved mover (MM) is not a cause for concern, for it was only introduced in DA III 10 to make sense of the fourth element, when desire was divided. So, there is here a genuine tripartite scheme, that aligns with the initial, unrefined version that Aristotle gives in DA III 10 433b13–14 before subdivision. But simply labelling the elements of Physics VIII 5’s tripartite scheme is not sufficient for a comparison with DA, especially because of the questions raised in the previous section. If we agree, as I think we should, that in DA and MA ‘it is clear that Aristotle takes human and nonhuman animals to be self-movers’ (Coren 2019a: 368), then we can assume that he upholds the strictures on self-motion established in the argumentative arc of Physics VIII.
Fundamentality of the Separability Thesis in Physics VIII’s Account of Self-Motion
To more accurately compare the two versions of the 3S, then, it is helpful to examine Aristotle’s general discussion of self-motion in Physics VIII. I suggest that seeking to establish what is essential to Aristotle’s understanding of self-motion in Physics VIII will rectify the somewhat lackluster results reached by simply aligning the two schemes. Here, I defend the view that the Separability Thesis is Aristotle’s primary piece of theoretical machinery for explaining self-motion. Note that though this principle is not so named in the literature, it is nevertheless frequently discussed (Coope 2015; Ferro 2022: ch. 2; Waterlow 1982: ch. 5; Morison 2004; Ross 1955: 435–440).15
The Separability Thesis (ST) prior to Physics VIII 5
Early in Physics VIII, Aristotle notices that animals have a unique relationship to locomotion: they can in the right circumstances initiate their own movements, whereas inanimate things cannot. In the context of his dialectic, he thus advances animals as an obvious counterexample to the opinion that what can move has either always been in motion or else is never in motion.16 While his use of terminology in Physics VIII 1–6 does not always definitively denote animals (ζῷα), sometimes referring more broadly to the ‘animate’ (ἔμψυχα), I think it’s fair to say that animals are the genuine case of interest for self-motion (see esp. 2 252b17–23, 2 253a15–20, 4 254b14–33, 6 259b1–16).17 He first mentions them in VIII 2:
The fact [that motion sometimes seems to start from nothing] is evident above all in the case of animate beings [τῶν ἐμψύχων]; for it sometimes happens that there is no motion in us and we are quite still, and that nevertheless we are then at some moment set in motion, that is to say it sometimes happens that we produce a beginning of motion [ἀρχὴ κινήσɛως] in ourselves from within ourselves [ἐν ἡμῖν], without anything having set us in motion from without. We see nothing like this in the case of inanimate things, which are always set in motion by something else from without: the animal [τὸ ζῷον], on the other hand, we say, moves itself [αὐτό φαμɛν ἑαυτὸ κινɛῖν] (VIII 2 252b17–23).18
Aristotle is struck by the fact that animate beings can move themselves in a way that inanimate beings cannot. Crucially, sometimes we produce ‘a beginning of motion in ourselves from within ourselves,’ without external influence. Nevertheless, for well-traversed reasons, pertaining to the fact that for Aristotle platonic-style monistic self-motion is impossible and ultimate origins of motion must be unmoved (Coope 2015; Ferro 2022: ch. 2; Waterlow 1982: ch. 5), this claim will not go unqualified. And though Aristotle’s τὸ αὐτό ἑαυτὸ/αὑτὸ κινοῦν locution is often translated as ‘self-mover,’ nothing in that phrase necessitates a platonic interpretation on which a monistic self-mover acts as a first mover by itself being in motion.
Because Aristotle thinks first movers are unmoved, he has resources to deflect another common concern about self-motion. Some (e.g. Furley 1978) have held that at VIII 2 253a11–21 and at VIII 6 259b1–16, where Aristotle implies that environmental factors can trigger self-motion, he thereby makes the claim of animal self-motion insignificant by qualifying it so heavily (cf. Gill/Lennox 1994: Introduction xv–xvi).19 Though somewhat peripheral to my main contention, I am sympathetic to Ferro’s view that Aristotle supports ‘weak causal autonomy’ but not ‘strong causal autonomy’ (2022: 218, 239–264).20 Environmental factors can contribute to the conditions for self-motion without undermining its authentic occurrence.
At the beginning of VIII 4, Aristotle presents for the first time the Separability Thesis. He arrives at it after a taxonomy of motion, which I read as follows (VIII 4 254b7–24):21
Figure 1 is supposed to divide all the types of motion countenanced by Aristotle at the chapter’s beginning. The solid lines subdivide the specified categories into further subcategories. The first distinction is between per se and per accidens motion (cf. DA I 3 406a4–20). Per accidens (κατὰ συμβɛβηκὸς) motion includes (perhaps among other possibilities, given that the clause starts with οἷον) the kind that occurs whenever a part of a greater whole moves. We can set this type aside, like Aristotle does, as irrelevant to present considerations.22 Then Aristotle says in one breath (254b12–14) that there are four sub-candidates of καθ’ αὑτά motion. There clearly are four sub-candidates, but organizing them as I have, with motion φύσɛι and βίᾳ καὶ παρὰ φύσιν taking precedence in the hierarchy, is an interpretive choice; one could instead view those as species of motion ὑφ’ ἑαυτοῦ and ὑπ’ ἄλλου. (Note that the ὑφ’ ἑαυτοῦ locution is distinct from the one Aristotle uses to describe self-motion: αὐτό ἑαυτὸ/αὑτὸ κινɛῖν). Regardless, the permutation of these labels creates four categories: three live and one void. The category of motion that is ‘through force’ and ‘by itself,’ though theoretically possible, is in fact null.
Figure 1
Physics VIII 4 (254b7–24) Taxonomy.
Aristotle’s taxonomy allows him to capture a notable oddity: motion occurring ‘naturally’ and ‘by another.’ Paradigmatic examples of things moving thus are animals’ bodies and the elements. The former is more pertinent to present considerations. He says that ‘the body [σῶμα] of an animal may be in motion naturally as well as against nature [φύσɛι καὶ παρὰ φύσιν],’ legitimating the presence of ὑπ’ ἄλλου motion within the classes of both φύσɛι and βίᾳ καὶ παρὰ φύσιν motion (254b18–19).23 Thus, the body of the animal is always moved ὑπ’ ἄλλου, but can be moved naturally or unnaturally.24 When the whole animal moves itself, however, it satisfies the definition of natural motion, which occurs whenever ‘the source of motion of a thing is in the thing itself’ (254b16–17).25 An important implication of Aristotle’s taxonomy, then, is that animal bodies are capable of exhibiting a strange duality in their (always ὑπ’ ἄλλου) movements: sometimes they are natural, sometimes not (cf. Waterlow 1982: 214–215).
What are the implications of this observation? I take it that one reason Aristotle notes this duality is to advance the Separability Thesis at the end of the opening segment of VIII 4 (254b7–33). Immediately following the taxonomy, he states that an animal is an example of something that initiates motion ‘by itself’ (ὑφ’ ἑαυτοῦ) and ‘naturally’ (φύσɛι) (254b14–15). Next he makes the more commonsensical observation occurring throughout Physics VIII that the animal as a whole (ὅλον) self-moves (αὐτὸ ἑαυτὸ κινɛῖ) (254b17–18). Importantly, Aristotle claims shortly thereafter that even things moving themselves (αὐτὰ ὑφ᾽ αὑτῶν) show that a moving object is moved by something (254b24–25, 27–28); more about that in a moment. Several lines later, Aristotle states the grand result of these considerations: ‘thus in animals the mover and the moved are separate [διῃρημένον]’ (254b31–32),26 i.e., the Separability Thesis.
How does Aristotle arrive at ST from the observations in the foregoing paragraph? Roughly, the idea seems to be the following. Notice, first, that the use of ὑπό in the expression αὐτὸ ὑφ’ ἑαυτοῦ already implies a bifurcation.27 For motion ‘by’ something is a case of what Graham (1999: 76) calls ‘transitive motion’ in which ‘A moves B,’ even if A = B. Such motion is to be distinguished from intransitive motion, where ‘A moves.’28 Thus, the expression applied to animals—αὐτὸ ὑφ’ ἑαυτοῦ—already implies, without providing details, that an animal moves in the transitive sense, with a special ‘by means of’ (ὑπό) relation joining the placeholders A and B. Aristotle’s general statement, including the carefully chosen word ὅλον, seems to confirm this impression: though the animal ‘self-moves’ (αὐτὸ ἑαυτὸ κινɛῖ) ‘as a whole’ (ὅλον), it is not right to say that it does so ‘by means of’ (ὑπό) the whole.
Notice that Aristotle never says that the animal’s body moves ὑφ’ ἑαυτοῦ. Rather, only the whole animal does that. Why does Aristotle emphasize that the body is moved both ‘naturally’ and ‘contrary to nature’? While inexplicit, the implication of his claim seems to be that because a part of an animal (namely its body) is capable of unnatural motion (which is always ‘by another’) there’s reason to think that even its natural motions are ‘by another.’ If so, even when a whole animal moves αὐτὰ ὐφ᾽ αὑτῶν, the animal’s body must be set in motion by something other than itself. Obviously, this something else cannot be external to the animal (since the motion is natural), so there must be a separate (διῃρημένον) mover within the animal. The conclusion then follows that the animal has minimally two parts relevant for locomotion; namely, a moved part and a (transitively) moving part.
In the remainder of Physics VIII 4 and 5, ST frequently continues to appear, indicating that likely Aristotle thinks it important (VIII 4 254b30–33, 255a12–18; VIII 5 257b12–15, 257b22–23, 258a1–8, 258a18–21, 258a22–25; cf. MA 10 703a11–14). He seems to arrive at this central thesis from the observation that animal bodies are moved naturally and unnaturally, but always ὑπ’ ἄλλου, so that he must posit a separate internal source of motion, thereby generating the two parts articulated by ST.29
The context of the tripartite scheme of Physics VIII 5
Ross seems right to title his analysis of Physics VIII 5 ‘The first movent is not moved by anything outside itself,’ where ‘movent’ is an archaic abstract noun for anything that causes movement. The last line of chapter four states, ‘all things that are in motion must be moved by something,’ and chapter five attempts to argue that all moving things are set in motion either by a further thing that is also moved by another or else by something that ‘moves itself’ (256a21, 256a34-b1).30 It will seek to establish that ‘the series brings us at some point or other to a mover of this kind’ (256b2–3),31 that is, a self-mover. The chapter then doesn’t analyze self-movers directly, but contends that chains of movers terminate in a self-mover (or, more precisely, an unmoved mover within the self-mover). I examine several key texts here to argue that, in context, the Physics VIII 5 version of 3S is in fact derivative upon Aristotle’s more paradigmatic expression of self-motion.
Defeasibility of instruments
The instrument appearing in the middle of the Physics VIII 5 tripartite scheme seems to be an optional ingredient. Early in the chapter, Aristotle introduces an example where a hand belonging to a man moves a stone by means of a stick. At 256a26–27, Aristotle writes, ‘but if something initiates motion by itself, it is not necessary for there to be another by means of which it initiates motion [ᾧ κινɛῖ].’32 First, this phrase provides grounds for thinking that the various instrumental datives scattered throughout the early part of VIII 5 are parallel to that used in the tripartite scheme, especially since he uses the identical phrase for this intermediate moved mover: ᾧ κινɛῖ. The phrase, of course, also appears in DA III 10’s 3S.
Second, however, this phrase provides good reason to think that there is something derivative about the tripartite scheme. For, Aristotle says explicitly, self-motion does not require a separate instrument. Thus, I take Aristotle’s admonition that the instrument is sometimes optional, as a strong indication that, whatever the function of the scheme might be, it is not a basic analysis of self-motion. But this tentative conclusion does not depend only on the text of lines 256a26–27 (nor the similar claims at 256a5–6 and 257a18–19).
The alphabet analogy as an application of ST
In the later part of VIII 5, following his articulation of the tripartite scheme, Aristotle gives a more in-depth analysis of self-movers. In this context he advances an analogy that offers ideal conditions for a comparison between the 3S and the ST. The ‘alphabet analogy,’ as I shall call it, has several features that assure its relevance to both ST and the tripartite scheme.
After a ‘fresh start,’ Aristotle proposes an approach in which he assigns letters to the abstract, unspecified parts of the self-mover. Immediately before developing his alphabet analogy, Aristotle reiterates ST as the conclusion of a lengthy argument against the possibility that the animal moves itself ‘as a whole,’ the details of which I must regrettably forego. He states: ‘Therefore in the whole of the thing we may distinguish that which imparts motion without itself being moved and that which is moved; for only in this way is it possible for a thing to be self-moved’ (258a1–2).33 Following this background remark, Aristotle introduces the alphabet analogy, seeming to give it as an explication of ST:
Further, if the whole moves itself [αὐτὴ αὑτὴν κινɛῖ], part of it will cause motion, part will be moved. ABΓ, therefore, will be moved both by itself [ὑφ’ αὑτῆς] and by ABΓ alone [ὑπὸ τῆς Α]. And since what causes motion may either be moved by another or be unmoved [ἀκίνητον], and what is moved may either cause some motion or cause none, the self-mover [τὸ αὐτὸ αὑτὸ κινοῦν] must be composed of a part that is unmoved [ἀκίνητου] but causes motion and also of a part that is moved but does not necessarily cause motion, but may or may not cause it. Call the part that causes motion but is unmoved ABΓ something that is moved by A and on account of which [τὸ ἐφ᾽ ᾧ] Γ moves, Γ something that is moved by B but moves nothing else (for even if there are several intermediaries before Γ, let us suppose only one). The whole ABΓ, then, moves itself. But if I take away Γ, AB will move itself, with A causing motion and B being moved, but Γ will not move itself, nor will it be moved at all (258a3–15).34
I take his opening statement to roughly restate the Separability Thesis, though now with alphabetical markers indicating an unmoved mover and a moved thing (which need not move anything further). The overall strategy attempts to establish that only two elements are needed to explain self-motion. For this reason, the third element Γ is non-essential for self-motion, though it may be included as a further moved thing at the chain’s end.35
Aristotle seems willing to expand ST to include more than two elements. If I am right, such expansion doesn’t contradict the fundamentality of ST, but shows that it can be used flexibly, including within the tripartite schemes. Presently, I take just two such indications of its flexibility. The first is the revealing acknowledgment at 258a11–12: ‘even if there are several intermediaries…let us suppose only one’ (cf. 256a5–6, 257a18–19). Though this statement does not imply the optionality of the intermediary altogether, it indicates that Aristotle seems to view modifications of ST to include more than the two essential stages (unmoved mover and moved thing) as helpful, but defeasible, explanatory tools. The second indication of the flexibility of the implementation of ST is his temporary addition of Γ to the more basic scheme, even if its inclusion is part of an argument to reaffirm that ST explains self-motion without it. In fact, this addition seems to bear directly on the tripartite scheme, because of his use of the phrase τὸ ἐφ᾽ ᾧ at line 258a10.36 He explains that A moves Γ ‘on account of’ B, the use of the dative recalling the instrumental dative (ᾧ κινɛῖ) of the second stage of the 3S.
In what follows, I want to get more precise about how ST’s elements can give rise to the 3S, without compromising the integrity of either model. I begin with the simpler case of the ‘AB’ analogy, before proceeding to the more complex ‘ABΓ’ case. In the AB case, there is a plausible alignment between ‘A’ from the alphabet analogy and the ἀκίνητον κινοῦν of the tripartite scheme. For the entire animal (‘AB’) is ‘moved by A,’ just as the τὸ κινοῦν of the tripartite scheme moves all the subsequent moved things. Classifying ‘B’ is more challenging, for the relationship between it and the motion of the whole of ‘AB’ is not specified. However, the middle of the passage, falling between the simple and more complex alphabet analogies offers some help. There, Aristotle explains, in full adherence to ST, that the self-mover must be composed of something that is ἀκίνητον and something that is κινούμɛνον (the latter of which might move nothing further).37 Given the context of this sentence, it seems permissible to assume that each of these parts can be associated with the letters of the previous sentence, yielding: A = ἀκίνητον and B = κινούμɛνον.
What bearing does this result have on the tripartite scheme? Actually, even the basic alphabet analogy already contains three elements. Notice, that Aristotle introduces the compound item ‘AB’ in the first instance as a stand-in for the whole self-mover (αὐτὴ αὑτὴν κινɛῖ). For we have not only A and B independently, but also their conjunction: AB. A provisional alignment between the simple alphabet analogy and the tripartite scheme is now possible:
(A) What imparts motion as something unmoved (UM)
(B) That by which the mover imparts movement—the instrument of motion (IM)
(AB) What is moved (ME)
Not everything about this picture is perspicuous. In particular, he never explicitly calls B an instrumental mover. So, one might reasonably wonder whether the relationship between B and AB is really parallel to that between the instrument of motion (IM) and the moved entity (ME). But I think this reading is supported by at least two favorable considerations. First, Aristotle frequently notes that the last in series of movers may, though need not, move further items (e.g. 256b15–16). Thus, just because Β is κινούμɛνον gives no reason for thinking that it cannot move something further. Second, in the expanded versions of the analogy including Γ, Β is clearly said to move at least one further item ‘by being moved by another’ (258a16–17).38 If the instrumentality of B is permitted in principle, it seems odd to rule out its ability to both move and be moved in the simple AB formulation.
But this preliminary analysis precedes a more sophisticated picture. For in the second half of the passage he introduces the more complex use of the alphabet analogy with three elements: ABΓ. This time he is more explicit that ABΓ as a whole ‘self-moves’ (αὐτὸ ἑαυτὸ κινɛῖ). One might attempt alignment between the new alphabet analogy and the 3S, as follows:
(A) What imparts motion as something unmoved. (UM)
(B) That by which the mover imparts movement—the instrument of motion (IM).
(Γ) That which is moved but does not move (?)
(ABΓ) What is moved (ME)
As can be seen, it is difficult to classify the third stage, since we are told explicitly that the final stage is the whole self-mover (258a12–13).
I reject here two possibilities. (i) The first idea would be to say that Γ is also a moved entity (ME). I reject this, firstly, because it is unparsimonious—there would be two (ME)’s. Secondly, in response to the idea that we demote ABΓ from being an (ME) and then elevate Γ alone to that status, lines 258a12–13 provide strong enough evidence that the whole (ἅπαν) ABΓ is the moved thing. A final way of establishing this point is to revert to the DA tripartite scheme, where Aristotle explicitly categorizes the final stage as the whole animal (τὸ ζῷον), which in the context of Physics VIII is simply the whole self-mover (cf. VIII 2 252b22–23: τὸ δὲ ζῷον αὐτό φαμɛν ἑαυτὸ κινɛῖν). Thus, since ABΓ must be the (ME), Γ on its own cannot be.
(ii) A second idea would be to correlate B with the moved mover (MM) from the developed DA 3S, which would then free up the instrumental mover (IM) for alignment with Γ. Then it would be parallel to the developed ‘quadripartite’ scheme of DA. There are at least three problems with this suggestion. The first is that the relationship between the object and faculty of desire in the DA scheme is sui generis and not appropriated to the context of Physics without great risk. Second, as noted, B is more or less explicitly categorized as (IM) when Aristotle uses the instrumental dative (τὸ ἐφ᾽ ᾧ) with respect to it. The third problem is that, unlike in the DA scheme where the relationship between the instrument (ᾧ κινɛῖ) and the whole animal is clearly adumbrated, Aristotle here makes no mention of how the motion of Γ and ABΓ are related. For these reasons I reject this proposal.
So how should we interpret the scheme to make up for the lacuna at the third step? I offer one possibility. The solution requires simply accepting the outcome of his argument in the second half of the passage: ‘But if I take away Γ, AB will [still] move itself’ (258a13–14). The point of the argument is to show that though one can add more movers at the end of the chain, they don’t contribute to self-motion’s fundamental analysis, which requires just two metaphysical components: A + B. On this view, in fact, Γ is a disposable argumentative tool. This reading is confirmed by his concluding comment after the given passage, that in fact ‘only AB moves itself’ (258a17–18).39 On this reading, too, we can confirm that the best comparison between the alphabet analogy and the tripartite scheme is that which uses the simple analogy (only AB) and the tripartite scheme, as given above. The unmoved mover (UM) is A, the instrument of motion (IM) is B, and the conjunction AB is understood as the whole self-moved entity (ME).
One minor worry is that this view entails that AB is a conjunction of elements that includes an unmoved mover (UM). It might seem odd to say that τὸ κινοῦν ἀκίνητον is part of κινούμɛνον μὴ κινοῦν μηδέν. In response it could be said that, even though AB includes A, which is an unmoved mover, it doesn’t include it in virtue of its ability to cause motion, so that we should still classify the whole AB as the (ME). In fact, this seems just what is implied when Aristotle contends that the soul can be moved only κατὰ συμβɛβηκός as part of the whole animal (cf. DA I 3 406b5–10).
An important conclusion from these considerations is that ST can be adapted to make different kinds of points in different argumentative contexts. More fundamentally, however, it shows that the 3S can be made consistent with ST, because the latter, through the conjunction of its two constituents, immediately creates a three-fold scheme: A, B, and AB.
Aristotle concludes his reflections on the alphabet analogy with a restatement of ST:
So it is clear that it is not through some part of the whole being of such a nature as is capable of moving itself that the whole moves itself: it moves itself as a whole, both being moved and imparting motion through containing a part that imparts motion and part that is moved. It does not impart motion as a whole nor is it moved as a whole: it is A that imparts motion and B alone that is moved (258a22–27).40
I take the concluding sentence here not as a contradiction of the interpretation advanced above, but rather as the correct articulation of an internal view of a self-mover. Though self-movers may move other external items, ST turns out to be the foundational principle giving the minimal factors necessary for animal locomotion.
Positive Outcomes
In this section, I outline a few benefits of this conclusion. If the argumentation heretofore is on the right track, then it is finally possible to assess what these results contribute to the understanding of how ST underlies the DA 3S, as well as to offer a resolution to a common worry about the unity of self-movers.
The Separability Thesis in De Anima
Since the Physics scheme’s relation to the Separability Thesis is more perspicuous and has been discussed at length, I focus in this section on the more difficult case of the relation between the DA 3S and ST. The essential point is that Aristotle’s metaphysically basic analysis of self-motion is not lost in the DA tripartite scheme, even if its presence is veiled. For in neither 3S is the basic stipulation violated that self-movers are composed (minimally) of an unmoved mover and a moved part. Rather, the schemes complexify the picture, but do so in harmony with the claim in Physics VIII 5 that moved things may, though need not, move further entities (256b15–16, 258a7–8). Consolidating the schemes yields the following picture.
Table 1 records the different schemata, with motion proceeding from left to right. The challenging element to classify is the (MM) stage of the DA scheme, introduced to account for the unique role played by the faculty of desire. The arrows indicate that, as mentioned at the end of §2, there are two main interpretive possibilities (cf. note 9). Either one can accommodate the faculty of desire to the (UM) element by insisting that it is actually ἀκίνητον properly speaking (with, e.g., (Ps-)Philoponus 1897: III 10 591.12-19), or contrarily, one can accommodate it as an additional (IM) by stating that it is a set of corporeal thermic alterations (with, e.g., Corcilius 2020: 341–2). In support of the second option, as noted in in §5.2.2., at least in Physics VIII 5 Aristotle openly allows that intermediates may be plural in number (cf. 256a5–6, 257a18–19, 258a11–12). But this debate need not be settled to see that the DA 3S is an application of ST.
Table 1
Correlations between the Schemes.
| Stage | (1) τὸ κινοῦν ἀκίνητον | (1b) τὸ κινοῦν καὶ κινούμɛνον | (2) ᾧ κινɛῖ | (3) τὸ κινούμɛνον |
|---|---|---|---|---|
| Symbol | (UM) | (MM) | (IM) | (ME) |
| Separability Thesis (ST) | (A) Unmoved Part | (B) Moved Part | (AB) | |
| Physics Scheme (3S) | What imparts motion being unmoved | That by which the mover imparts motion | Moved Entity | |
| De Anima Scheme (3S) | Object of Desire |  | Bodily Instrument | Whole Animal |
That DA III 10 433b13–433b18 includes an unmoved mover (UM) is uncontroversial, even if the next step is. What is important is that the unmoved part move (transitively) something else. On the one hand, if one thinks that the faculty of desire is properly speaking ἀκίνητον and thus integrated into (UM), this second part would be the bodily instrument. On the other hand, if the faculty of desire is a first instrument of motion (IM), then the second part is simply the faculty of desire itself. Notice that on either view, the DA scheme can be understood as an application of ST: on the first view (A) is the object of desire + the faculty of desire and (B) is the bodily instrument; on the second view (A) is simply the object of desire and (B) is the faculty of desire. Either way, ST’s basic stipulation that there be (minimally) an unmoved moving part and a moved part is preserved.
An objection to ST: Is the unity of a self-mover compromised?
Commentators have often noticed a potentially serious objection to Aristotle’s preferred view of self-motion (Coope 2015; Morison 2004; Waterlow 1982: ch. 5). The objection says that if Aristotle wants to defend the view that everything that is moved is moved by something else, then, if the self-mover has one part that is set in motion and another that sets in motion, it seems the self-mover is divided into two, undermining its unity. If so, then Aristotle’s account of self-motion destroys the very notion it describes. Since he clearly applies the ST within self-movers, this objection could be quite dangerous for Aristotle. I briefly consider two responses, the second stemming from my overall argumentative strategy.
Reply 1: the nature of separability
The first reply preserves the unity of the self-mover by appealing to metaphysical resources that Aristotle himself provides. These pertain to the nature of the ‘continuous’ (συνɛχές), ‘contact’ (ἁφῆ), and a distinction between actual and potential separability.
One way to see that a self-mover must be composite without undermining its unity depends on Aristotle’s understanding of the continuous. Aristotle states in Physics VIII 4 that if something is fully continuous (συνɛχές), it cannot move itself (αὐτὰ ἑαυτὰ κινοῦσιν) (255a12–18).41 The reason he gives is that the internal continuity of such a thing makes it one (ἕν) so that it cannot suffer change (ἀπαθές). The extreme unity of such a thing, in fact, is the very reason that it cannot self-move. Preliminarily, it should be stated that whatever kind of unity we want the self-mover to have, it won’t violate this stipulation. This response, however, is a burden-shifting tactic rather than a direct reply.
A further response bases itself on Aristotle’s strange comments about contact, which build on the foregoing paragraph. It is clear, for Aristotle, that motion usually occurs by two entities touching each other. In this respect, recall part of Aristotle’s parenthetical remark from the VIII 5 tripartite scheme that the mover and the instrument must ‘be touching each other’ (ἅπτɛσθαι γὰρ ἀλλήλων) (256b19). This statement reflects a more general view that contact is an important part of explaining motion (cf. Physics V 3). But contact is also something less than being continuous (συνɛχές). So, for example, looking again at Aristotle’s interesting remark in chapter four at 255a12–18, he says that something is ἀπαθές inasmuch as it is one (ἕν) and continuous not by contact (συνɛχὲς μὴ ἁφῇ). The implication is that there is a looser kind of continuity that both unifies the entity and permits self-motion. He reiterates this kind of stipulation at the end of the alphabet analogy passage, stating that either both parts of the self-mover are touching (ἁπτόμɛνα) or at least one touches the other (θατέρου θάτɛρον).42 Aristotle appears to thread a middle way: the self-mover has a unity by possessing a certain kind of continuity, which is secured by at least one of the two parts, A or B, touching (ἅψɛται) the other.
Coope (2015) invokes VIII 5 258a32-b2 to present a final strategy. This strategy claims that the unity of the self-mover is maintained since it is only potentially, not actually, divisible. In fact, ‘A sign that this is so is that many self-movers no longer move themselves when divided’ (Coope 2015: 262). But, as Coope admits, there are unaddressed objections to this piece of data, like the fact that some self-movers, when divided, create two self-movers.
Reply 2: the adaptability of ST
But I think my argument has also made available a second, more general, kind of reply. When Aristotle uses the ST to explore the implications of self-motion, it gets applied to a wide array of different scenarios. We thus see the ST, arguably, underlying the tripartite schemes of both Physics VIII 5 and DA III 10, the alphabet analogy, as well as unaddressed instances like the hand-stick-stone example in Physics VIII 5.
As these examples show, the ST is a flexible scheme capable of manipulation to serve various purposes. It sets minimal conditions for self-motion, without prohibiting greater complexity within actual self-movers. As argued, there is no indication in Physics VIII, for example, that self-movers must have an instrument. Additionally, there may be many intermediaries (256a6, 258a11) and the statement that the final moved thing doesn’t necessarily move anything further (256b15–16; cf. MA 6 701a1–2) implies that it could.
In fact, in his more developed schemes of animal locomotion in De Anima and de Motu Animalium Aristotle utilizes this leeway. In the DA tripartite scheme, for example, Aristotle’s division of stage one into the ἀκίνητον object of desire and the κινούμɛνον faculty of desire, adds a second moved mover creating, as noted, a quadripartite scheme. Of course self-movers don’t require two moved movers, but that is permitted. Similarly, in MA, the bodily instrument is specified as a form of ‘connate breath’ (σύμφυτον πνɛῦμα) (MA 10 703a5–11, 19–21) that through expansion or contraction pushes and pulls (10 703a19–20) and thus ultimately moves the limbs. This process could have many steps and sometimes relevant bodily organs are even described in the plural as ‘instrumental parts’ (8 702a8–9, 17). I don’t take such development to suggest that ST is not metaphysically fundamental. Rather, it shows only that the ST may not be sufficiently sensitive to the empirical physiological and psychological details required to fully explain animal locomotion.
Returning to the unity challenge, these applications of the ST arguably show that having multiple parts jointly responsible for the self-mover’s production of motion doesn’t undermine its unity. Just as it would miss the point to suggest that Aristotle’s quadripartite analysis of animal locomotion in DA III 10 divides the animal into four, so too one need not worry that ST splits the animal into two. If my suggestion is correct, dividing the organism into parts with distinct functions for the task of explaining locomotion doesn’t threaten the animal’s unity, whether introduced by the basic division in ST, or by more complex schemata like 3S. Instead, the account of an organism’s unity ought to be sought in other metaphysical analyses, like that of form and matter.
Conclusion
In a difficult passage of DA III 10 Aristotle presents a tripartite scheme of animal locomotion. It might seem odd that, in his paradigmatic exposition of animal locomotion, he appropriates a scheme of general kinetics from Physics VIII and ignores work on self-motion in the very same book. I have suggested that the pressure of this oddity is alleviated once it is recognized that self-motion as described by the Separability Thesis underlies both tripartite schemes.43 Regardless of the precise parts that move the animal, there will minimally be two: a mover and a moved. My suggestion is that the Separability Thesis should be able to withstand adaptation to specific empirical concerns raised both within Aristotle’s system of animal locomotion and perhaps within our own modern equivalents as well.
Notes
[1] This threefold partition of motion (κίνησις) between qualitative, quantitative, and local movement is articulated in several places (e.g., II 1 192b13–15, V 1 225b5–9, VII 2 243a35–39; cf. DA I 3 406a12–14). Aristotle seems to think that locomotion is somehow ‘primary’ (VII 2 243a39–40, VIII 7 261a27–28), perhaps especially because animals have agency is somehow limited to locomotion (VIII 2 253a14–15). Note that the threefold division integrates into a broader fourfold division of change (μɛταβολή) that includes in addition change ‘with respect to substance’ (III 1 200b32–4). For a clear articulation of these divisions see Lettinck’s introduction to Philoponus: On Aristotle Physics 5–8 (1994: 18) and Shields (2016: 119–121). Ferro (2022: 14–16) has the view that κίνησις κατὰ τόπον is a genus of which φορά is one species; nothing in my exposition depends on denying or affirming that view.
[2] Ferro (2022: 149) gives one account of the role that self-motion plays in Aristotle’s broader argument: ‘I shall emphasise that the alleged inconsistencies with the familiar account depend on the very specific interests that shape the core argument of Ph. VIII, where animal motion, far from constituting the main object of enquiry, is only a single – if particularly important – item on a much broader agenda. Since the investigation is driven by cosmological concerns, the focus on efficient-causal chains in the analysis of sublunary natural motions (notably, elemental motion and animal locomotion) throughout Ph. VIII 1 to 6 should come as no surprise.’ Cf. Waterlow (1982: 216).
[3] It would take us too far afield to address the relevant passages (MA 6 700b35–701a5; 10 703a4–6; 10 703a28–29; Cf. Rapp, Christof and Primavesi, Oliver (eds.) 2020b for Greek text and translation) but see Corcilius (2020) and Hankinson (2020) for discussion. Metaphysics XII 7 1072a19–30 and perhaps DA III 12 434b29–435a3 present similar schemes.
[4] ʼEπɛιδὴ δ᾿ ἐστὶ τρία, ἓν μὲν τὸ κινοῦν, δɛύτɛρον δ᾿ ᾧ κινɛῖ, τρίτον τὸ κινούμɛνον· τὸ δὲ κινοῦν διττόν, τὸ μὲν ἀκίνητον, τὸ δὲ κινοῦν καὶ κινούμɛνον· ἔστι δὲ τὸ μὲν ἀκίνητον τὸ πρακτὸν ἀγαθόν, τὸ δὲ κινοῦν καὶ κινούμɛνον τὸ ὀρɛκτικόν (κινɛῖται γὰρ τὸ κινούμɛνον ᾗ ὀρέγɛται, καὶ ἡ ὄρɛξις κίνησίς τίς ἐστιν ᾗ ἐνέργɛια), τὸ δὲ κινούμɛνον τὸ ζῷον. Greek text from W.D. Ross (1956) and Förster (1912). All translations of DA from Shields (2016) with slight modifications. There are textual difficulties, especially at the crucial 433b17–18, where I read κινούμɛνον ᾗ ὀρέγɛται with Ross as opposed to Förster’s ὀρɛγόμɛνον ᾗ ὀρέγɛται, but I opt for Förster’s reading of ᾗ ἐνέργɛια in line 18, since the alternative of ἡ ἐνέργɛιᾳ is an introduction of Torstrik.
[5] Early Greek commentators make this interpretation explicit. Themistius, e.g., writes, there are ‘in fact four [stages]’ since ‘the cause of movement is twofold: one is unmoved, as with the practical good, the other is moved and causes movement, as with desire’ (Themistius 2014: 120.28-30 based on Greek from Themistius 1882). μᾶλλον δὲ τέτταρα… ὅτι τὸ κινοῦν διττόν, τὸ μὲν ἀκίνητον ὥσπɛρ τὸ πρακτὸν ἀγαθόν, τὸ δὲ κινούμɛνον καῖ κινοπυν ὥσπɛρ ὄρɛξις. Cf. Simplicius (1882: III 10 300.29-301.10); Rapp (2020a: 279–284). Note that I do not adjudicate to this debate given i) the side taken for the reason mentioned in the text and ii) the fact that I ultimately argue that both schemes depend on a metaphysically more basic account.
[6] Cf. Etheridge’s (1968: 28). Note that I generalize Rapp’s ‘moved body’ (MB) to ‘moved entity’ (ME).
[7] See Rapp (2020a: 277–78) for discussion.
[8] ᾧ δὲ κινɛῖ ὀργάνῳ ἡ ὄρɛξις, ἤδη τοῦτο σωματικόν ἐστιν· διὸ ἐν τοῖς κοινοῖς σώματος καὶ ψυχῆς ἔργοις θɛωρητέον πɛρὶ αὐτοῦ. Inquiry into that which is ‘common to body and soul’ is taken up in MA.
[9] The problem is quite simple to formulate (see Corcilius 2020: 341–2 for an especially clear overview). Firstly, Aristotle famously forsook Plato’s view that the soul is a self-mover, instead holding that the soul moves the body without itself being moved (Furley 1978; Gertz 2010; Morison 2004; see esp. DA I 3 405b31-406a2: ‘[it is] impossible that motion [κίνησιν] belong to the soul’). Secondly, however, Aristotle seemingly also posits that ὀρɛκτικόν is a power of the soul. And, thirdly, in the context of the tripartite scheme as it appears in DA III 10 (and MA 10), Aristotle tells us that ὀρɛκτικόν is a moved mover (τὸ κινοῦν καὶ κινούμɛνον). On their face, these three claims constitute a striking contradiction. I am inclined to side with the standard approach, denying proper κίνησις to the soul, perhaps primarily given the remarks Aristotle makes at DA III 10 433a31-433b3, which seem to straightforwardly categorize ὀρɛκτικόν as a δύναμις of the soul; nevertheless, I can’t defend this interpretation here.
[11] See Hicks (1965: 561); Polansky (2007: 521–22); Shields (2016: 362). Though they all note the source of the tripartite scheme in Physics VIII 5, they do not elaborate. Hicks writes simply that the scheme is ‘from the doctrine laid down in the Physics,’ whereas Polansky notes that, ‘outside the De anima, Aristotle is typically concerned to distinguish the first, unmoved mover from any intermediates that are moved movers and the last thing that is moved without moving anything else’ (p. 522) before continuing to his analysis of the DA version. Corcilius (2008: 269 n. 30) goes further in at least acknowledging that the Physics scheme is about motion in general: ‘Aristoteles hier eine Einordnung seiner Theorie der animalischen Ortsbewegung in seine allgemeine Theorie der Bewegung vornimmt.’
[13] τρία γὰρ ἀνάγκη ɛἶναι, τό τɛ κινούμɛνον καὶ τὸ κινοῦν καὶ τὸ ᾧ κινɛῖ. τὸ μὲν οὖν κινούμɛνον ἀνάγκη κινɛῖσθαι, κινɛῖν δ’ οὐκ ἀνάγκη· τὸ δ’ ᾧ κινɛῖ, καὶ κινɛῖν καὶ κινɛῖσθαι (συμμɛταβάλλɛι γὰρ τοῦτο ἅμα καὶ κατὰ τὸ αὐτὸ τῷ κινουμένῳ ὄν· δῆλον δ’1 ἐπὶ τῶν κατὰ τόπον κινούντων· ἅπτɛσθαι γὰρ ἀλλήλων ἀνάγκη μέχρι τινός)· τὸ δὲ κινοῦν οὕτως ὥστ’ ɛἶναι μὴ ᾧ κινɛῖ, ἀκίνητον. Greek text from W.D. Ross (1955) and translations of Physics throughout based on both Hardie and Gaye in Barnes (1995) and Graham (1999) with some modifications.
[14] Note that Ferro (2022: 252–277) appears to contest this consensus: ‘Even more importantly, it seems both striking and hardly fortuitous that Aristotle avoids talking about the soul, but rather keeps using the extremely cumbersome phrase τὸ κινοῦν πρῶτον καὶ τὸ αἴτιον τοῦ αὐτὸ ἑαυτὸ κινɛῖν’ (p. 252). Since for Aristotle a physical object could not move while being unmoved, however, the generally accepted view has at least one strong argument in its favor.
[15] For example, Waterlow (1982: 208): ‘That there is some difference between changer and changed within the self-changer is one of the few points on which Aristotle is quite definite.’
[16] The precise argumentative strategy throughout Physics VIII 1–6 is not my concern here. See Ferro (2022: ch. 2); Graham (1999); Waterlow (1982: ch. 5); and note 2.
[17] Coren (2019b: 60), discussing the possible self-change of plants, is surely right to conclude: ‘without sensation a creature cannot possess the directing faculties of self-change, namely desire and phantasia… plants are neither self-changers nor capable of self-change.’
[18] πολὺ δὲ μάλιστα τὸ τοιοῦτον ἐπὶ τῶν ἐμψύχων ɛἶναι φανɛρόν· οὐδɛμιᾶς γὰρ ἐν ἡμῖν ἐνούσης κινήσɛως ἐνίοτɛ, ἀλλ’ ἡσυχάζοντɛς ὅμως κινούμɛθά ποτɛ, καὶ ἐγγίγνɛται ἐν ἡμῖν ἐξ ἡμῶν αὐτῶν ἀρχὴ κινήσɛως, κἂν μηθὲν ἔξωθɛν κινήσῃ. τοῦτο γὰρ ἐπὶ τῶν ἀψύχων οὐχ ὁρῶμɛν ὁμοίως, ἀλλ’ ἀɛὶ κινɛῖ τι αὐτὰ τῶν ἔξωθɛν ἕτɛρον· τὸ δὲ ζῷον αὐτό φαμɛν ἑαυτὸ κινɛῖν. Cf., τό τɛ γὰρ αὐτὰ ὑφ’ αὑτῶν φάναι ἀδύνατον· ζωτικόν τɛ γὰρ τοῦτο καὶ τῶν ἐμψύχων ἴδιον (VIII 4 255a5–7).
[19] Morison (2004) defends self-motion from this attack by pinning doubts about its authentic occurrence on self-movers’ compositeness.
[20] In a similar vein, see the statement of Coren (2019a: 376) that ‘self-motion is always dependent on and affected by changes going on inside and outside the animal (growth, decay, digestion, respiration, environmental conditions) that are not in the animal’s control.’ I set aside further pursuit of this topic here.
[21] Note that Aristotle seems to think that the taxonomy applies to moved things and movers, given his claim that he is characterizing τῶν κινούντων καὶ κινουμένων. However, it might be problematic to see both as operative in every category of the taxonomy; motion that is both ὑφ’ ἑαυτοῦ and φύσɛι, e.g., might reasonably be thought to apply only to movers. Generally, see Ross’s paraphrase of the latter part of the taxonomy: ‘while all ὑφʼ ἑαυτῶν κινούμɛνα are φύσɛι κινούμɛνα, some ὑπʼ ἄλλων κινούμɛνα are φύσɛι and some are βίᾳ κινούμɛνα’ (1955: 694; cf. Graham 1999: 78). Some (Coren 2019b; Graham 1999) focus on the chapter’s implications for elemental motion, which is surely important for the arc of the argument for an unmoved mover, nevertheless I focus on the animal case as most relevant for self-motion.
[22] But see Graham (1999: 74–89) for the view that per accidens motion actually should have been kept in play.
[24] An exception ‘depends upon the kind of motion that it may chance to be suffering and the kind of element of which it is composed’ (διαφέρɛι γὰρ ὁποίαν τɛ ἂν κίνησιν κινούμɛνον τύχῃ καὶ ἐκ ποίου στοιχɛίου συνɛστηκός) (VIII 4 254b19–20).
[27] Note that Aristotle seems to imply that if motion is ‘by itself’ ὑφ’ ἑαυτοῦ, it is also natural.
[28] Graham attributes some points in his discussion to Waterlow (1982).
[29] I do not question that the potentiality/actuality distinction highlighted by Coope (2015) is put in service of defending the thesis in chapter five. But I do think that the principle’s appearance in VIII 4 should be explained.
[33] τῆς ὅλης ἄρα τὸ μὲν κινήσɛι ἀκίνητον ὂν τὸ δὲ κινηθήσɛται· μόνως γὰρ οὕτως οἷόν τέ τι αὐτοκίνητον ɛἶναι. Aristotle’s argumentative strategy in the section of text which precedes this quotation is to reduce various possible explanations of how the animal could be self-moved as a whole to ‘accidental motion,’ thus ruling them out as plausible candidates for how the animal moves itself (257b12–258a1).
[34] ἔτι ɛἴπɛρ ἡ ὅλη αὐτὴ αὑτὴν κινɛῖ, τὸ μὲν κινήσɛι αὐτῆς, τὸ δὲ κινήσɛται. ἡ ἄρα ΑΒ ὑφ’ αὑτῆς τɛ κινηθήσɛται καὶ ὑπὸ τῆς Α. ἐπɛὶ δὲ κινɛῖ τὸ μὲν κινούμɛνον ὑπ᾽ ἄλλου τὸ δ᾽ ἀκίνητον ὄν, καὶ κινɛῖται τὸ μὲν κινοῦν τὸ δὲ οὐδὲν κινοῦν, τὸ αὐτὸ αὑτὸ κινοῦν ἀνάγκη ἐξ ἀκινήτου ɛἶναι κινοῦντος δὲ, καὶ ἔτι ἐκ κινουμένου μὴ κινοῦντος δ᾽ ἐξ ἀνάγκης, ἀλλ᾽ ὁπότɛρ ἔτυχɛν. ἔστω γὰρ τὸ Α κινοῦν μὲν ἀκίνητον δέ, τὸ δὲ Β κινούμɛνόν τɛ ὑπὸ τοῦ Α καὶ κινοῦν τὸ ἐφ’ ᾧ Γ, τοῦτο δὲ κινούμɛνον μὲν ὑπὸ τοῦ Β, μὴ κινοῦν δὲ μηδέν· ɛἴπɛρ γὰρ καὶ διὰ πλɛιόνων ἥξɛι ποτὲ ɛἰς τὸ Γ, ἔστω δι’ ἑνὸς μόνου. τὸ δὴ ἅπαν ΑΒΓ αὐτὸ ἑαυτὸ κινɛῖ. ἀλλ᾽ ἐὰν ἀφέλω τὸ Γ, τὸ μὲν ΑΒ κινήσɛι αὐτὸ ἑαυτό, τὸ μὲν Α κινοῦν τὸ δὲ Β κινούμɛνον, τὸ δὲ Γ οὐ κινήσɛι αὐτὸ ἑαυτό, οὐδ᾽ ὅλως κινήσɛται.
[35] Cf. 256b15–16. One might suppose that it is B and not Γ that is expendable. My counter to this line of thought is Aristotle’s admission that the second element moves (transitively) but ‘not out of necessity’ (μὴ κινοῦντος δ᾽ ἐξ ἀνάγκης), implying there need be no third element, i.e., Γ.
[37] It is important to note that of course the animal can move further things. The point is simply that these further downstream motions are inessential to the analysis of self-motion (cf. MA 6 701a1–2).
[40] δῆλον δὴ ὅτι τὸ πᾶν αὐτὸ ἑαυτὸ κινɛῖ οὐ τῷ αὐτοῦ τι ɛἶναι τοιοῦτον οἷον αὐτὸ αὑτὸ κινɛῖν, ἀλλ’ ὅλον κινɛῖ αὐτὸ ἑαυτό, κινούμɛνόν τɛ καὶ κινοῦν τῷ αὐτοῦ τι ɛἶναι τὸ κινοῦν καὶ τὸ κινούμɛνον. οὐ γὰρ ὅλον κινɛῖ οὐδ’ ὅλον κινɛῖται, ἀλλὰ κινɛῖ μὲν ἡ τὸ Α, κινɛῖται δὲ ἡ τὸ B μόνον.
[41] Cf. Physics V 3 for definitions of not only συνέχɛς, but also ἅμα, ἅπτɛσθαι, μɛταξὺ, and ἐφɛξῆς.
Acknowledgements
I gratefully acknowledge the support of the Paul Schmitt Foundation for a speaker series on Aristotle’s De Anima at the University of Neuchâtel in 2023, as well as the open-access publication of several articles on Aristotle’s De Anima, including this one, submitted in response to an associated Call for Papers. I also gratefully acknowledge helpful suggestions and/or comments written and unwritten from an audience of the doctoral colloquium at the Munich School of Ancient Philosophy (LMU), Reier Helle, Santiago Chames, Antonio Ferro, Edward Mezger, Lucas Álvarez-Maldonado, two anonymous reviewers, and, most especially, to Andreas Anagnostopoulos.
Competing Interests
The author has no competing interests to declare.