Derrida's Post-Structuralism is the earliest and the pivotal version of Post-Structuralism, but it is not the only version. Another version of almost equal importance is the version associated with Foucault in his 'genealogical' period of the 1970s. In many respects, Foucault's 'genealogy' follows on from where his 'archaeology' left off, extending into new areas of discourse the campaign against science and humanism. Thus, 'genealogies . . . are precisely anti-sciences'; and 'genealogy [is] a form of history which accounts for the constitution of knowledges [savoirs], discourses, domains of objects, etc., without having to refer to a subject'.1 But in other respects, there is a decisive philosophical difference between 'archaeology' and 'genealogy'. And although Foucault does not appear to be directly influenced by Derrida – and even displays considerable animosity towards Derrida – yet this difference is in the end analogous to the difference between Saussure's theory of 'langue' and Derrida's theory of Writing.2