to a neutrality, then the measure which appeared proper to apply to the appreciation of all those objects is at the same time put an end to, and one must fix a similar valuation on everything.
Perhaps our opponent will say, “Are then appearances trustworthy or deceitful?”12 We answer that, if they are trustworthy, the other side has nothing to object to those to whom the contrary appearance presents itself. For, as he who says that such and such a thing appears to him is trustworthy, so also is he who says that the contrary appears to him. And if appearances are deceitful, then they do not deserve any confidence when they assert what appears to them to be true. We are not bound then to believe that a thing is true, merely because it obtains assent. For all men do not yield to the same reasons; and even the same individual does not always see things in the same light. Persuasion often depends on external circumstances, on the authority of the speaker, on his ability, on the elegance of his language, on habit, or even on pleasure.
They also, by this train of reasoning, suppress the criterion of truth. Either the criterion has been decided on, or it has not. And if it has not, it does not deserve any confidence, and it cannot be of any use at all in aiding us to discern truth from falsehood. If, on the other hand, it has been decided on, it then enters into the class of particular things which require a criterion, and in that case to judge and to be judged amount to the same thing; the criterion which judges is itself judged of by something else, that again by a third criterion, and so on ad infinitum. Add to this, say they, the fact that people are not even agreed as to the nature of the criterion of truth; some say that man is the