Usually, when junior professors publish scholarly articles, they are lucky to elicit more than a yawn. But last week the philosophical musings of Rebecca Tuvel, an assistant professor at Rhodes College in Memphis, Tenn., provoked a spasm of fury.

Ms. Tuvel’s paper, published in the feminist philosophy journal Hypatia, takes on one of the weakest points of the left’s mania for identity politics. Ms. Tuvel asks why society is increasingly willing to embrace people who identify as “transgender,” even as it rejects those who identify...