ABSTRACT
In the dialogue that bears his name, the young Theaetetus is invited to say wh at knowledge iso After a false start, he comes up with the following conjecture: 'Knowledge', he suggests, 'is perception' (151 e 3). In short order, Socrates introduces a couple of other items into the discussion. There is the proclamation of Protagoras: 'Man is the measure of all things', Protagoras declared at the beginning of his book Truth, 'of those that are, that they are, and of those that are not, that they are not' (152 a 2-4). And then there is the dictum co which a whole line of many of the most eminent thinkers of Greece would subscribe: Protagoras, Heraclitus, Empedocles, and many, many others would all accept the dictum that 'all things are the offspring of flux and motion' (152 e 8). These three slogans are worded quite differendy. In the end however they all come co the same thing. For, as Socrates expounds them, each turns out to be just a different formulation of the most sustained attack yet upon the view that error is possible. That attack, and Placo's response to it, will be the subject of this chapter.
