A mode of philosophy which determines ontology, that is, the nature of being, by distinguishing between two types of properties a particular thing may have: those which are essential to it, and those which are merely accidental. The former are sometimes referred to as essence. In contemporary critical theory the most common form of this way of thinking is to be found in gender studies, where sexual difference is held by certain thinkers to be an essential difference between men and women and by extension a common cause for action (in both a positive and negative sense---sexism is the bias of one gender against another, while feminism is similarly an action of one gender against another). The work of Butler, Judith, however, challenges the essentialist position by offering a conception of gender that focuses more on the âaccidentsâ of performativity. Similarly, Haraway, Donna challenges the essentialist view of gender by challenging the underlying assumption that it is possible to distinguish between male and female in an absolute sense to begin with. See also strategic essentialism.