With the publication of Gender Trouble in 1990, Judith Butler spearheaded a movement in feminist theory which has become known as 'radical constructivism'. Taking its departures from psychoanalytic and poststructuralist theory, and also informed by speech-act theory, Gender Trouble contends (albeit with sophistication and nuance infinitely greater than this) that gender is not an internal essence, but one produced 'in anticipation' by a repeated and naturalised set of acts, behaviours and stylings. Gender and sexual categories are held in place by the restrictive norms of heterosexuality, but these can be revealed as artificial by their very citability -- as demonstrated in extremis by, for example, drag and camp performance.
In Bodies That Matter (1993) Butler extends and complicates the theories put forward in Gender Trouble to contend that not only gender, but the materiality of the body itself, is discursively and performatively produced. We cannot, therefore, speak of a natural, prelinguistic, 'given' body, because what we think we know about bodies is an effect rather than a cause of signification. As with Gender Trouble, this is not to say that bodies are entirely, unchangingly determined by language, but a recognition that, in Butler's words, there can be 'no reference to a pure body which is not at the same time a further formation of that body' (1993, p. 10). Referring to a body is thus, in quite a strict linguistic sense, always almost performative or constitutive, and governed largely (though not entirely) by habitual understandings and norms (such as heterosexism). Again, the citation and iterability of the norms that subjects are expected 'naturally' to embody belies their instability in a classic deconstructive manoeuvre: the natural or intelligible body shores itself up against, and thereby defines or summons the appearance of the deviant or unintelligible (just as the legitimate summons the illegitimate, the authentic the false, the proper the improper, and so forth). The 'performance' of alternative sexualities and gender identities both denaturalises normative suppositions, and pushes for the articulation of new bodily possibilities.
Butler outlines her theory of how bodies are produced, or materialised, in discourse, and clarifies the oft-cited notion of performativity in its twinned senses of speech-act and theatrical agency. The textual style in this instance is relatively straightforward by Butler's standards: her work is renowned for what can seem like a wilfully opaque syntax. This, however, is central to her critique, which is shot through with a relentless critical suspicion of the 'common sense' of linguistic transparency.