 Platonists do not deny that we have ideas of mathematical objects. What they deny is that our mathematical sentences are about these ideas. Thus, the dispute between platonism and psychologism is primarily a semantic one. Advocates of psychologism agree with platonists that in the sentence ‘3 is prime’, ‘3’ functions as a singular term (i.e., as a denoting expression). But they disagree about the referent of this expression. They think that ‘3’ refers to a mental object, in particular, an idea in our heads. It is this semantic thesis that platonists reject and that the above Fregean arguments are supposed to refute. More specifically, they're supposed to show that the psychologistic semantics of mathematical discourse is not correct because it has consequences that fly in the face of the actual usage of mathematical language.