Post Structuralism as a modern critical theory has its origin in asserting the unstable relationship between the signifier
and the signified. the signifier does not want to be tied to a single signified for example, poetry, dreams, jokes. This theory can be expressed in a number of characteristic post-structuralist positions:
The first position is that the author should not be considered as the origin of his text or the authority of its meaning.
The second position states that that there are no objective scientific discourses and anything like that does not exist at all.
The third position considers that literature cannot be isolated as a separate discourse and is always contaminated with the entire universe of discourse. It is not an isolated entity.
Ronald Barthes criticises the structuralist attempt to find the structure of
narrative saying that narrative draws upon the codes which form a grid of possible meanings permitting no ultimate closure. Even if the readerly texts try their best to limit and restrict the possibilities of meaning, they cannot always be read, for certain plurality. The writerly text actually celebrated its openness and encourages the reader's productive activity resembling the writer's own in its deployment of codes and readers may give their own meanings and interpretattions to the text.
Nietzsche who considered all knowledge to be will to power was a major influence on Michel Foucault who further examined the
historical construction of knowledge and commented that what is called rational and scholarly is determined not by absolute standards of reason but by unspoken rules, institutional constraints and the power of particular discursive practices. Edward Said further took up foucault's historical stand of post structuralism and emphasises the pressures of reality that constrain the possibilities of knowledge. He strongly felt that literary crtics can grasp a past text only within the discursive archive of present.