The first perspective from which the pseudes doxa, the false view, is examined, is that of the guiding principle of knowledge, that we either know something or we do not know it. If you know something you do not not-know it and vice versa. In light of this the false view is at one and the same time a view and not a view. It is a view through which we think we know something, but at the same time we do not know it, because our view is false. An example of this state of affairs is given:
Someone who knows both Theaetetus and Socrates, sees a man, who is actually Theaetetus, coming towards him, but who he takes for Socrates. Thus he takes Theaetetus, whom he knows, as not he whom he knows, i.e. Theaetetus, but as someone else, i.e. as Socrates, but it is not Socrates.
The outcome of this is that someone who knows both Socrates and Theaetetus also simultaneously does not know them, in other words he confuses them. Therefore in the case of the false view, one knows, and does not know one and the same thing. (191) But the principle of knowledge that one either knows or does not know something makes this impossible – therefore the conclusion is reached that the pseudes doxa cannot exist.