  Feminist philosophers have also changed the history of philosophy by appropriating its ideas for feminist purposes. From the perspective of negative canon formation, the history of philosophy is a resource only in so far as it describes the theories and thinkers that were most deeply mistaken about women. Other feminist historians of philosophy have found important resources for feminism in canonical philosophers. Indeed, they have found valuable concepts even in the worst offenders of the negative canon, like Aristotle and Descartes.