Plato has now answered Simmias’ objection about the soul’s being a harmony. He has yet to answer Cebes’ objection about the soul being like a tailor who, after making several suits (bodies) for himself, finally expires nonetheless like one of his suits (bodies). But at this point Socrates offers a digression about natural philosophy—the philosophy of nature, which we now call natural science.
Socrates begins with a quasi-autobiographical reminiscence. When he was young, he was enthralled by natural philosophy. Do we think, he wondered, with blood, air, or fire? Is the brain the organ where thinking takes place? Do we grow by taking in food and drink? But if something becomes larger by having something added, how does that change take place? The more he studied, the more confused he became.
“One time,” he continues, “as I heard someone reading from a book of Anaxagoras … a statement that mind is the ordering principle and cause of all things, I was impressed by this explanation and thought that in some sense it must be right that mind should be the cause of all things. And I realized that if this was so, mind … would set all things in order and arrange each individual thing in whatever way was best. So if you wanted to find out the reason for which each thing comes to be or perishes or exists, the thing to find out would be in what way it was best for that to be or to be acted on or act. Indeed, on this theory there is no need for you to study anything else concerning that thing or any other, than what is fairest and best ….”[10]
This insight struck Socrates as an important key to understanding the cosmos and how it works: seek what would be the best way for any natural object to exist, and, once you grasp that, attribute that function to the natural order. Socrates reports that he got hold of Anaxagoras’ book and searched it for the application of this principle. But to his dismay, he found that Anaxagoras never exploited this insight, but rather explained phenomena as did his predecessors, in terms of physical and material causes, including “airs and ethers and waters,” that did not address the goal or purpose of existence. “That seemed to me like someone saying that Socrates did everything he did by means of mind, and then, attempting to specify the causes of each thing I did, he should say in the first place that I am sitting here now because my body is composed of bone and muscles, and the bones are solid and have joints separating them from each other, the muscles are able to contract and relax, surrounding the bones together with flesh and skin which contain them … allowing me to bend my limbs and for this reason I am able to bend over and sit down.”
All of this would, however, miss the whole point, which is the real reason Socrates is sitting here, in prison, namely that “since the Athenians thought it best to condemn me, it has seemed best to me to sit here, and most just for me to remain and undergo the punishment which they have imposed. For by the dog, I am sure these muscles and bones would have in motion to Megara or Boeotia long ago, borne by a conviction of what was best, if I had not thought it better to submit to whatever punishment the city decreed than to flee and make my escape!”[11]
Plato here reminds us that Socrates could, like some of his countrymen in similar circumstances, have skipped town before his trial. Even after the trial, Socrates’ friends had bribed the prison guards and planned to break him out of prison, but he chose to accept his fate for moral reasons. Human actions are carried out for specific purposes, governed by a judgment of what is best for the agent. Could the events of the cosmos be similarly understood?
Using an account of what is best as his paradigm, Socrates points out the folly of not being able to distinguish what is really a cause from what is not. Among the events that do not count as causes, he includes what we might call the mechanical causes of phenomena, such as the bones and muscles that hold our bodies together. These are necessary conditions of our motions, but they do not provide the motives or reasons for our actions. Nor, presumably, do winds and vortexes and the like account for the motions of the heavens.
Yet Socrates has not been able to identify the real causes of phenomena, and so he takes refuge in a second-best approach: he will look for a hypothesis that accounts for a phenomenon and accept as true what agrees with the hypothesis. We are reminded of the method that Socrates introduced in the Meno, of providing a hypothesis and seeing what it implied (see ch. 14.3, 14.6*). Is virtue teachable? Suppose (hypothesize) that virtue is knowledge; then it would be teachable. And if it were teachable, there would be teachers of it.
What makes something beautiful? What else could be beautiful than the Beautiful itself? The simplest hypothesis for any feature something has is apparently the existence of the corresponding property. Helen of Troy is beautiful because of Beauty; she is wise because of Wisdom; she is good because of Goodness. This kind of answer is the simplest and the safest one.[12] Schematically, something is F because of F-ness. Each thing is F because it partakes of (metechei) F-ness.[13] The properties that are referred to in the expression F-ness are Forms. To make sense of the world, it appears that we must posit the existence of Forms (singular eidos; plural eidē).[14]
[10] Plato Phaedo 97b-98c.
[11] Plato Phaedo 98e-99a.
[12] Plato Phaedo 100b-d.
[13] Plato Phaedo 101c.
[14] Plato Phaedo 102a-b. The word eidos in common use meant ‘kind, type, class.’ Plato does not really use technical vocabulary (as his student Aristotle will). He even uses synonyms for eidos, including idea (the Greek original of our English word ‘idea’; but the Greek term does not signify a mental representation, but rather the same thing as eidos) and genos.