Cebes’ challenge leads to what is typically called Socrates’ four “immortality arguments,” which structure the core of the dialogue. Despite this common label, Cebes’ challenge does not ask Socrates to show that the soul is immortal, and Socrates’ first three arguments do not claim to show immortality. Instead, Cebes challenges Socrates to address people’s fear that the soul disperses and so is destroyed when someone dies; not being destroyed upon death is, I argue, different from being immortal. After discussing Cebes’ challenge, the chapter turns to the cyclical argument, providing a new account of its basic structure. It is based on an agreement that does not require Socrates to say anything here about the nature of the soul. Nonetheless, the argument is important for aiming to show that a Pythagorean view is correct – reincarnation – by understanding death and rebirth as part of a much larger phenomenon: the coming to be and passing away of opposite things.

This chapter begins by arguing that to understand Socrates’ (alleged) autobiography, we need to appreciate that he distinguishes between the terms “aitios” (responsible) and “aitia” (cause). Socrates’ account should be understood against the backdrop of the sophisticated treatments of aitios and aitia and of hypotheses in fifth-century medical treatises. At the same time, the autobiography shows how Socrates – as portrayed throughout Plato’s dialogues – would engage with the natural scientific tradition: he shows his hallmark profession of ignorance; he becomes excited by the prospect of acquiring knowledge of the good; since he is unable to learn this from Anaxagoras or others, he proceeds in a way that does not require knowledge; instead, he hypothesizes the existence of the things sought by his typical “what is it?” question. I argue that Socrates might not be interested in teleology here, as opposed to simply being interested in knowledge of the good. Once we situate the method of hypothesis within the overall dialogue, we can see that it is supposed to help one slowly build rational trust in a theory, thereby avoiding the cycle of trust and doubt that leads to misology.

Ancient Greece provided the setting for the first detailed, recorded hypotheses about the causes of human activity. In the search for first principles of life, tentative explanations included: The naturalistic orientation of the Ionian physicists Democritus, Heraclitus, and Parmenides looked to some basic physical element in nature as this first principle. A biological orientation, developed by Alcmaeon, Hippocrates, and Empedocles, held that bodily physiology is the key. Pythagoras held that life is transcendent of the material world and found in the essential coherence of mathematical relationships. The Sophists posited a pragmatic orientation that denied the value of trying to seek out first principles, relying instead on observations of life as it is lived. Finally, Anaxagoras and Socrates, rejecting the Sophists, proposed the existence of a soul that defines humanity. This humanistic orientation developed the notion of the spiritual soul that possesses the unique human capabilities of the intellect and the will. The soul was elaborated as the central element in the interpretation of life offered by Plato and Aristotle. By the end of the Greek era the critical themes and issues of psychology as well as the methodological approaches were well identified and structured.

Why would a fourth-century BC Atomist – Anaxarchus – express his scepticism about knowing the truth of things by imaging these as scene-painting? The comparison seems already to have been made by Democritus and Anaxagoras, who according to Vitruvius had been impressed by something an Athenian painter named Agatharchus had written on perspective. This chapter offers a detailed scrutiny of a range of texts that have a bearing on the interpretation of Vitruvius’ claim. It argues that Agatharchus was probably author of a pioneering treatise on stage-building, which included a section on scene-painting lauding its power to create the illusion of a whole three-dimensional world. Anaxagoras will have taken this claim as cue for his dictum: ‘Appearances are a sight of things unseen’ – in the sense that there is no break between the macroscopic world of ordinary observation and the microscopic world which explains it. The Atomist Democritus will no doubt have imparted a quite different spin to Anaxagoras’ slogan in praising it. But it is unlikely that either Presocratic was prompted to a mathematical interest in perspective by reading Agatharchus. It is only with the Hellenistic philosophers, and especially Epicurus, that optics begins to leave its trace on general epistemology.

In this chapter I develop the point that the knowledge Aristotle particularly wants to explain is knowledge of beings. I work from certain problems he thinks prevented his predecessors from defining psuchē satisfactorily. I focus on two issues in particular: whether knowledge is “like by like” and “alteration.” I argue that the problem raised by both issues is at bottom the same. If knowledge is alteration, and is “like by like,” the result is that our knowledge is so colored by arbitrary facts about us as to belie the idea that it is really of beings as they are “in themselves.” If knowledge is not “like by like,” and leaves its subjects unaltered, the result is to make it unintelligible in principle why subjects of knowledge have anything to do with its putative objects. In short, the problem is how to respect the fact that knowledge is of beings, as they are in their own right, without rendering that fact an inscrutable mystery. For these points I rely on De Anima I 2, III 3, and Metaphysics G 5. These texts combine to establish that, for Aristotle, the outstanding representative of the problems in this area is Protagoras.

This section substantiates the claim that Xenophanes, Parmenides and Empedocles played an instrumental role in the emergence of what may be termed the Classical conception of literature – that is, the view that a work of literature is a mortally crafted artefact that reflects a true state of affairs only symbolically or mimetically – by drawing attention to evidence for their influence on certain important developments in fifth- and fourth-century BCE poetics. These include (a) fifth-century practices of allegorical interpretation; (b) Gorgias’ statements that poetry is deceptive and is a kind of charm or drug; (c) Democritus’ physical explanations for poetic inspiration and composition; (d) Democritus and the sophists’ analytical approaches to language; and (e) the conceptions of mimesis presented by Plato.

Deployment of the notion of kosmos has been much discussed in the scholarship on Presocratic philosophy. But diakosmos and diakosmêsis have been almost entirely neglected. This chapter argues that in describing the business of articulating ‘mortal belief’ as diakosmos, Parmenides bequeathed to his successors among the Presocratics a question – intended as deflationary – about the main agenda for physics and physical explanation: how the universe is arranged. He coined a concept designed to articulate it. Diakosmos was a concept his successors were determined to reinflate, but only at the price of contestation between believers in a single world produced by design and proponents of infinite undesigned worlds. And in Aristotle, diakosmêsis is re-invested with a hint of the deflationary.