A Third and Underlying Principle

Physics I 6 addresses the question of the number of principles and motivates the need for an underlying principle in addition to the contrary ones argued for in chapter 5. Physics I 6 ends in aporia about whether there are two or three principles, an aporia which is resolved with Aristotle’s own account in I 7. This chapter focuses on two issues. First, it explores how Aristotle’s arguments for contrary and underlying principles give rise to the aporia. Second, it discusses Aristotle’s puzzling attitude towards, and use of, materialist views in I 6 and, more generally, in book I. Though Aristotle brings out deep tensions between his own hylomorphic conception and materialism, he also seems to downplay them for the purposes of arguing for an underlying principle. I suggest that this is a result of trying to motivate a hylomorphic conception of natural substance from within a more familiar materialist framework.

Principles and Contraries

Contrary to readings that consider Physics I 5 as doxographical, this chapter argues that it is the first step of a constructive inquiry whose conclusions, paradoxical as they may seem, are never dismissed later. Its main thesis is that the contraries are principles of coming-to-be and passing-away, but it also endorses the stronger thesis that the principles are contraries. Although it appeals to doxographical considerations, its main section is an inductive argument which heralds the concept of privation, without mentioning it explicitly. This chapter studies the relationship between the opposition of contraries and that of possession and privation, as well as the way Aristotle reduces the intermediates to the contraries. Finally, it shows how the device of sustoikhia (‘series’) allows Aristotle to identify the opposition between possession and privation as the first pair of contraries and to organize the positions of his forerunners in respect of their proximity to the truth.

One and Many

In Physics I 4 Aristotle turns to those who, in his view, practised bona fide natural philosophy by allowing change and multiplicity. But instead of providing a survey of the pluralist options, Aristotle focuses on those who produced plurality out of an initial one. He singles out Anaxagoras and provides a detailed discussion and refutation of his theory of mixture. This chapter examines what features of Anaxagoras’ theory could motivate Aristotle’s exclusive focus on him. It suggests that Anaxagoras is particularly interesting for Aristotle, because he offers a model in which the character that emerges as the outcome of the change is already there at the beginning, without however being manifest. In this sense, Anaxagoras’ theory gets closest to Aristotle’s solution to the puzzle of change. In assessing Aristotle’s objections, the chapter also argues against the widely held view that his critical discussion commits him to the theory of minima naturalia.

Responding to the Platonists

This chapter examines Aristotle’s rejection of a Platonist theory positing two principles: Form and the Great and Small. He complains that, under the latter, privation is not distinguished from the subject of coming to be. This chapter discusses the background for this dyadic theory in the Philebus and the Timaeus. It suggests that Aristotle’s opposition only makes sense if Platonists were proposing to extend it to cover comings to be such as biological reproduction. It also discusses whether, dialectically, Aristotle wins against Platonism within Physics I 9, and in the wider context of his biology. The chapter notes that when the explanandum is eternal motion, the triad of principles is useless, because there is no distinct principle of privation. So, Aristotle himself is chained to a Platonist-style dyadism. The chapter concludes by drawing a connection between this theory and Aristotle’s first mover as both final and efficient cause of eternal motion.

The Route to Solving the Eleatic Puzzle

This chapter analyses Aristotle’s solution to the infamous ‘old Eleatic problem’ about coming to be and passing away. According to Aristotle, the ‘old philosophers’ got off track due to their inexperience and concluded that since nothing can come to be from what is, since it already is, and since nothing can come to be from what is not, there is no generation at all and also no plurality of things. Aristotle’s solution involves making the right kind of conceptual distinctions, first, in terms of what it means for something to come to be from what is or from what is not qua what it is or qua what it is not, and second, by distinguishing coming to be in an accidental and in an absolute way. Aristotle concludes by solving again the same problem via a different method, namely by distinguishing between coming to be in actuality and in potentiality.

Looking for a Starting Point—The Eleatic Paradox Put to Good Use

This chapter starts the discussion about principles that runs throughout book I, as well as the discussion about Melissus and Parmenides that continues in chapter 3. It raises the paradoxical question of how to arrive at the principles of natural philosophy and how to establish that these are indeed the sought-after principles. In order to do so, Aristotle inquires into Eleatism, the position that denies the very existence of nature: this means that the best way to the principles might be discovered by taking on those who utterly reject them. That explains the equally paradoxical move of discussing the theses of people with whom it would seem impossible to discuss since they do not agree on the basics. Yet that can be done through the specific dialectical tactics of lusis. Certain ancient attempts at squaring the circle, mentioned in the course of the argument, are dealt with in Appendix I.

The Path to the Principles

Physics I 1 is a methodological introduction, not just to physics, but specifically to the investigation of principles. To gain scientific knowledge of nature, we must first determine its principles, but how do we determine these if we don’t know them already? This chapter distinguishes two readings of Aristotle’s claim that ‘at first it is rather confused things which are evident and clear to us, but afterwards, starting from these, the elements and principles become knowable when we divide these things’. On Reading A, we start by knowing compounds but not their elements. On Reading B, we start by knowing the compound more clearly than its elements, but also confusedly knowing the elements. We start by knowing the elements under universal descriptions and come to know them more clearly in substituting more particular descriptions. The chapter defends Reading B and show how it fits Aristotle’s procedure in Physics I and beyond.

Introduction: Some General Remarks on Aristotle’s Physics I

Physics I is a well-constructed logos. It aims at knowledge of the principles of physical change: it establishes that there are such principles and determines what they are and how many. Even if the results are general, its theories are fundamental for the entire Aristotelian study of the natural world. This introduction reconstructs the general structure of Physics I and its connection to Physics II. It distinguishes four stages in Physics I: an introduction, a doxographical section in which Aristotle is in dialogue with previous philosophers, a section in which he solves the main puzzles about change, and an endoxical confirmation of the theory established in the preceding section. Other points discussed are: to what kind of public Physics I is addressed, the difference between Aristotle’s theory and ancient cosmologies, the examples he uses, how to identify a single event, and his conception of essences.

The Principles of Natural Things—Two or Three?

This chapter examines part 2 of Physics I 7, in which Aristotle connects the concepts of what underlies and of the contraries with the question of what the principles of natural things are. He articulates the concept of the contraries involved in any given change in terms of the distinction between form and privation. He privileges form over privation, treating only form and matter as indispensable principles of natural substances. Furthermore, he focuses on the principles of the being and coming-to-be of substances, at the expense of the non-substantial forms of change such as alteration and locomotion. He also introduces the idea that form is not only a principle of natural substances once they have come to be, but also a principle from which they come to be. Aristotle employs these new thoughts in stating his own view of what the principles of natural things are: form, privation, and the substratum that underlies them.

The Complexity of the Subject in a Change

This chapter discusses Aristotle’s account of the role matter, form, and privation play in a change. It claims that Aristotle identifies a new item in the ontology, the hypokeimenon (subject) of a change, crucial for understanding the nature of change. This subject is a metaphysically complex item, the combination of some matter and a privation. Aristotle’s first, and best, example of such a metaphysically complex item is a seed, whose nature, fully specified, would be matter and privation. Such items are the ones in the world which are apt for engaging in change. Their complexity makes change intelligible, since they have a component that persists (matter) and a component that doesn’t (the privation). The interpretation offered differs from the more usual one by identifying the hypokeimenon with a complex item (e.g. a seed) rather than matter alone. This chapter explores the benefits and costs of the two interpretations.