The way I handled this reading was to read it once straight through, and then go back and re-read while making notes of my thoughts for the study group. Here are the notes I have so far, which I may add to later:
142a-143c
Blah, blah, blah. Reading this part is a big waste of time, IMO. I don’t really see why it needs to be here, other than setting the stage for the dialogue, and I’ve never been a big fan of the dialogue format anyway.
143d-144d
More stage-setting, but at least this time, it’s the beginning of the conversation we’re actually interested in reading.
144e-145a
Not everyone is qualified to make judgments about everything. One shouldn’t pay too much heed to the words of someone who has no particular expertise in whatever it is they’re talking about. For the most part, this is probably true, although the example Socrates uses—that Theodorus is unqualified to say two people resemble each other because he is not a painter—is a little faulty. The basic point is ok, though—if you want medical advice, ask a doctor, not a historian. But if you want to know the political climate of China in the 19th century, ask the historian. Duh.
145b-146c
Here, we’re finally getting somewhere. Knowledge is what one gains when learning about a subject. Does that really tell us what knowledge is, though? It doesn’t, not in any way that is useful. It is this problem that Socrates poses to Theaetetus: What is knowledge?
146c-147b
Knowledge may be gained about a number of things, but listing all of the things about which one might gain knowledge is not the same as identifying the nature of knowledge itself, so the question “What is knowledge?” remains unanswered.
147c
An identification of what knowledge is requires that we identify what knowledge is, universally, without reference to particular instances of knowledge.
147d
The purpose of this passage is to indicate that universality is not an arbitrary requirement when forming a definition. A proper concept must be able to stand for a potentially infiniate number of concretes.
147e-148b
In this passage, Plato is demonstrating the the steps of identifying the nature of a particular concept. It’s basically a process of categorization—recognizing similarities and differences, i.e. integration and differentiation. On the surface, it seems as though it isn’t that different from Aristotle’s epistemology or Objectivist concept-formation—but that’s only on the surface.
Plato isn’t writing about forming a concept, but rather recognizing the nature of a concept which already exists. This is why Theaetetus says he is trying to find a name “by which we could henceforth call all the roots,” as though the concept already exists is his mind, and the problem is identifying the concept. It would be a mistake to think that Plato is writing about concept-formation, since it would contradict his metaphysics from Phaedo.
148c-148d
In order to form a proper definition of “knowledge,” one must go about the same process used to form a definition of “square root.”
148e-151d
For the most part, this is a rather lengthy segue into Plato’s refutation of several false theories, but it isn’t entirely devoid of conent. Scorates’ role in the dialogue is revealed as being similar to that of a midwife. He is not obtaining knowledge himself, or divulging any knowledge, but is helping Theaetetus to recognize the knowledge he already holds, but cannot identify on his own.
I’m inclined to relate this again to Plato’s innate ideas.
151e-152b
This is Plato’s summary of the first view (Protagoras’) he intends to refute. In this view, perception and knowledge are the same thing, but perception of an object is always relative to the perceiver. What you perceive is true for you, and what I perceive is true for me, i.e. relativism.