The so-called Digression (172a1–177c4) is probably the least discussed part of the Theaetetus, perhaps because it is not easy to get the point of this part of the dialogue. In this paper my purpose is to give a plausible answer to the following questions: what is the role played by the Digression within the dialogue as a whole? And could we consider it merely an ethical interlude in an epistemological context?
From the point of view of content, the Digression doesn’t introduce anything new, beyond what Plato said in his middle dialogues. All the ideas the Digression points out have already been explained elsewhere: (1) the freedom of the philosopher, as opposed to the slavery of the orator, is a topic of the Gorgias; (2) the philosopher’s care for the soul rather than the body and the thesis that there is no virtue without wisdom are claimed in the Phaedo as well in the Republic; (3) that this wisdom is the knowledge of Forms and that it is a kind of purification and assimilation to god as far as possible is argued in the Phaedo and in the Republic. What conclusion can be drawn from that?
The only conclusion we may draw is that the importance of the Digression consists exactly in the fact that it does not add anything new to Plato’s philosophy and in this way it actually shows that the onto-epistemological background of the Theaetetus is the same background in play in the Phaedo, Republic and Phaedrus. Through the Digression, Plato warns us that the metaphysical and epistemological framework which we must use to make sense of the Theaetetus is still that of the middle dialogues, for the very good reason that every topic Plato accounts for in the Digression has already been explained in a more detailed way in his previous works. I think that, if rightly understood, the Digression states explicitly that the horizon of the middle dialogues is still in place and therefore that the Two-World Theory is still alive. If I am right, the Digression is not a mere ethical interlude, barely integrated to the rest of dialogue. Rather it plays a central role in marking the continuity between the Theaetetus and Plato’s middle dialogues. This continuity makes the Theaetetus not an indirect confirmation of Plato epistemology but a pivotal work in understanding the best human knowledge (alethes doxa meta logou) as philo-sophia and, consequently, the true goal of Plato’s epistemology.