Why does it seem that everything that I read in philosophy always uses "she" or "her" instead of "his" or "he"?

Hurray for singular "they". Apparently good writers have long used it-- This is not a new problem, or a new solution. 'A person can't helptheir birth', wrote Thackeray in Vanity Fair (1848), and evenShakespeare produced the line 'Every one to rest themselves betake' (inLucrece), which pedants would reject as logically ungrammatical. Quote (and more on the subject) is here .