The political practice of overlooking the fact that from a post-structuralism perspective essence (in a philosophical sense) are difficult to sustain both collocation and epistemology. For example, few feminist theory would agree that there is a set of definable attributes essential to the idea, the concept, or the actuality of woman. Yet the more one pushes this deconstruction line of thinking, the harder it becomes to establish common ground, or more especially common cause, sufficient to the needs of political action. If all women are irreducibly different, then why should they act together? The same problem besets all political groups defined by their identity (e.g. race, class, ethnicity, sexual orientation). For that reason, US-based Indian critic Spivak, Gayatri proposes the notion of a strategic essentialism which simultaneously recognizes the impossibility of any essentialism and the necessity of some kind of essentialism for the sake of political action. French feminism critic Irigaray, Luce has taken up this term in her work for precisely the same reason.