Aristotle’s theory of causes requires a first, unmoved mover outside the sublunary world, along with soul as first and unmoved mover in the natural world below. Aristotle separates the charmed group of causes headed by soul that are jointly sufficient for typical animal behaviour from external causes. The border between external and charmed is permeable: crops growing in the field are co-opted to become an instrument of soul that nourishes the animal. (Instruments of soul like the sumphuton pneuma are internal (...) to the animal from the start.) But no causes, not even the Unmoved Mover, may supersede soul as unmoved mover. (shrink)

Aristotle notoriously begins his examination of being in the sense ofdunamisandenergeiainMetaphysicsTheta with what he describes as the sense that is ‘most dominant’ but not useful for his present aim. He proceeds to define the not-useful sense ofdunamisas “the principle of change in something else or in itself qua other”, along with other senses derived from this primary sense. But what then is the useful sense? All that Aristotle tells us at the outset is that it is a sense that extends (...) “beyond things spoken of only in relation to motion” and nowhere in Book Theta does he explicitly identify the useful sense as such. This has allowed for very different interpretations of the useful sense in the literature, the primary ones being that it is (1) ‘possibility’, (2) the potential to receive a form, (3) being-potentially-x understood modally as encompassing all specific senses ofdunamis, and (4) capacity for substantial change. The present paper argues that there are significant problems with all of these suggestions and defends an identification of the useful sense ofdunamiswith the sense that Aristotle explicitly opposes to the not-useful sense at the start of Theta 8:phusis(‘nature’). This goes hand-in-hand with an identification of the useful sense ofenergeiawith ‘activity’ as distinguished from motion/change at the end of Theta 6. What makes these senses ofdunamisandenergeiathe useful ones for Aristotle’s present aim is that they are required to explain fully the priority ofenergeiatodunamisin substance defended in Theta 8, they support the identification in Theta 9 ofenergeiawith the good, and they explain the unity of the only substances that Aristotle recognizes as being genuinely substances: natural living substances. (shrink)

ABSTRACTIn Physics VIII, 5, 256b8-13, Aristotle maintains that it is impossible that there is no motion, because he proved earlier on that it is necessary that there is always motion. In Physics VIII, 1, 251b23-28, Aristotle said that it is necessary that if time is eternal, then motion is also eternal. In Physics VIII, 5, 256b8-13, Aristotle speaks on the contrary about the necessity of eternal motion. In this paper, we show that the argument expounded in Physics VIII, 1, 251b23-28 (...) entails that eternal motion is also necessary de sensu diviso. (shrink)

It might seem quite commonplace to say that Aristotle identifies fire, air, water and earth as the στοιχεῖα, or ‘elements’ – or, to be more precise, as the elements of bodies that are subject to generation and corruption. Yet there is a tradition of interpretation, already evident in the work of the sixth-century commentator John Philoponus and widespread, indeed prevalent, today, according to which Aristotle does not really believe that fire, air, water and earth are truly elemental. The basic premise (...) of this interpretation is that Aristotle takes fire, air, water and earth to be, in some sense, composite bodies and, as such, analysable into simpler constituents. But, of course, an element of bodies is defined by Aristotle himself as something into which bodies can be analysed, and which does not admit further analysis . So if fire, air, water and earth can be analysed into simpler or more basic constituents, then it would seem to follow that the latter ought to be considered Aristotle's true elements. These are usually identified as the primary contraries hot and cold, dry and wet; many, perhaps most, commentators would insist also upon prime matter as the subject upon which these contraries act. (shrink)

A lot of scholarly attention has been given to Aristotle’s account of how and why animals are capable of moving themselves. But no one has focused on the question, whether self-change is possible in plants on Aristotle’s account. I first give some context and explain why this topic is worth exploring. I then turn to Aristotle’s conditions for self-change given in Physics VIII.4, where he argues that the natural motion of the elements does not count as self-motion. I apply those (...) conditions to natural change in plants. Then I explore the reasons for and consequences of Aristotle’s argument that plants are incapable of sensation. I argue that for Aristotle plants cannot possess the directing faculties for self-change, namely, desire and phantasia. My goal is to show why growth, metabolism, and reproduction in plants would not count as self-change for Aristotle, despite many of these natural changes appearing as autonomous as the analogous changes in animals. This sheds light on how, for Aristotle, self-change differs from natural change. (shrink)

I examine the reasons Aristotle presents in Physics VIII 8 for denying a crucial assumption of Zeno’s dichotomy paradox: that every motion is composed of sub-motions. Aristotle claims that a unified motion is divisible into motions only in potentiality (δυνάμει). If it were actually divided at some point, the mobile would need to have arrived at and then have departed from this point, and that would require some interval of rest. Commentators have generally found Aristotle’s reasoning unconvincing. Against David Bostock (...) and Richard Sorabji, inter alia, I argue that Aristotle offers a plausible and internally consistent response to Zeno. I defend Aristotle’s reasoning by using his discussion of what to say about the mobile at boundary instants, transitions between change and rest. There Aristotle articulates what I call the Changes are Open, Rests are Closed Rule: what is true of something at a boundary instant is what is true of it over the time of its rest. By contrast, predications true of something over its period of change are not true of the thing at either of the boundary instants of that change. I argue that this rule issues from Aristotle’s general understanding of change, as laid out in Phys. III. It also fits well with Phys. VI, where Aristotle maintains that there is a first boundary instant included in the time of rest, but not a “first in which the mobile began to change.” I then show how this rule underlies Aristotle’s argument that a continuous motion cannot be composed of actual sub-motions. Aristotle distinguishes potential middles, points passed through en route to a terminus, from actual middles. The Changes are Open, Rests are Closed Rule only applies to actual middles, because only they are boundaries of change that the mobile must arrive at and then depart from. On my reading, Aristotle argues that the instant of arrival, the first instant at which the mobile has come to be at the actual middle, cannot belong to the time of the subsequent motion. If it did, the mobile would already be moving towards the next terminus and thus, per Phys. VI 6, would have already left. But it cannot have moved away from the midpoint at the very same moment it has arrived there. This means that the instant of arrival must be separated from the time of departure by an interval of rest. I show how Aristotle’s reasoning applies generally to rule out any continuous reflexive motion or continuous complex rectilinear motion. On my interpretation, however, the argument does not apply to every change of direction. When, as in the case of projectile motion, multiple movers and their relative powers explain why the mobile changes directions, distinct sub-motions are not involved. Aristotle holds that such motions cannot be continuous, not because they involve intervals of rest, but because they involve multiple causes of motion. My interpretation of the Changes are Open, Rests are Closed Rule allows us to make better sense of Aristotle’s argument than any previous interpretation. (shrink)