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

To the questioner: My sense is that either you are reading a mis-representative sample of philosophical writing or you are exaggerating the use of 'she' and 'her' because you have internalized the normative use of 'he' and 'his' and so examples that resist that norm stand out and perhaps wrankle. When I was an undergraduate in the mid 1980s, there was pressure to resist that norm -- but I don't have a sense that this resistance was completely successful in either philosophical or most non-philosophical writing. Certainly I don't see widespread use of gender-neutral pronouns and Louise's suggestion still sounds ungrammatical to my ear. In my own writing, I simply try use a mixed balance of gendered personal pronouns.