 Central to Frege’s and Husserl’s criticism of psychologism is the idea that psychologism turns out to be a relativism of sorts. Frege goes no further than to point out this reduction of psychologism to relativism, and, for the reasons given above, he makes no attempt to refute relativism. However, Husserl marshals a number of arguments against both Protagorean relativism and species relativism. If these arguments were successful, then psychologism would be unmasked as a self-refuting doctrine. A number of critics have tried to show that they are not successful. 