a1 University of East Anglia
Protagoras believes that all beliefs are true. Since Protagoras' belief that all beliefs are true is itself a belief, it follows (somewhat trivially, perhaps?) from Protagoras' belief that all beliefs are true that Protagoras' belief is true. But what about the belief that Protagoras' belief is false? Doesn't it follow, by parallel reasoning and not at all trivially, that if all beliefs are true and there is a belief that Protagoras' belief is false, then Protagoras' belief is false?
1 I am grateful to Thomas Baldwin, David Bostock, Nicholas Denyer, Martin Hollis, Marie McGinn and Antony Price for their criticisms and encouragement of this paper.