Cebes’ cloakmaker objection presents an alternative model of the soul according to which it is ultimately destroyed in the process of providing life to the body. Socrates’ final argument rejects this model by arguing that the soul’s bringing life to the body, far from destroying the soul, is precisely what ensures that it must be immortal and imperishable. In doing so, the argument identifies a way in which the soul has a characteristic of the divine – immortality – thereby specifying one way in which it is akin to the divine, as Socrates claimed in the kinship argument. Thus, the final argument responds to Cebes’ cloak maker objection in a way that further fills in the kinship argument’s account of the soul. The final argument also includes an important discussion of forms and ordinary objects. I argue that Socrates here identifies the most basic reason why forms cannot be ordinary, perceptible things: ordinary objects are receptive of opposites, whereas forms cannot be.

Plato’s dialoguesespecially the Republiclead us to wonder what the objects of mathematics are. For Plato, no perceptible three is unqualifiedly three, a necessary condition for being an object of knowledge. Aristotle controversially ascribes to Plato the view that mathematical objects are “intermediates,” between perceptibles and Forms: multiple but also eternal, lacking change, and separate from perceptibles. The hunt for or against intermediates in Plato’s dialogues has depended on two ways of understanding Plato on scientific claims, a Form-centric approach and a subject-centric (semantic) approach. Although Socrates does not present intermediates in the Republic, it is difficult to see how the units of the expert arithmetician or motions of the real astronomer could be simply Forms or perceptibles. The standard over-reading of the Divided Line, where the middle sections are equal, further obscures our understanding. The Phaedo and the Timaeus provide candidates for mathematical objects, although these have only some of the attributes ascribed to intermediates. We are left with no clear answer, but exploring options may be exactly what Plato wants.

In Plato’s dialogues, Socrates calls things like justice, piety, and largeness “forms.” In several of these dialogues, he makes clear that forms are very different from familiar objects like tables and trees. Why, exactly, does he think that they differ and how are they supposed to do so? This chapter argues that in the Phaedo Socrates does not assume that they are different, but rather, over five stages of the dialogue, provides an account of how and why they do so. To fully understand the claims made in the first stage, one must look to the next stage, and so on until the final stage. Socrates' ultimate reason for distinguishing forms from ordinary objects does not depend on our intuitions about things like justice and largeness, nor on the distinction between universals and particulars. Ultimately, forms cannot be ordinary objects because the form of f-ness must cause every f-thing to be f, but no ordinary object could serve as such a cause. They cannot do so because they have multiple parts and are receptive of opposites; by contrast, the form of f-ness must be simple and unchanging, since it causes every f-thing to be f.