Deconstructionism (or sometimes just Deconstruction) is a 20th Century school in philosophy initiated by Jacques Derrida in the 1960s. It is a theory of literary criticism that questions traditional assumptions about certainty, identity, and truth; asserts that words can only refer to other words; and attempts to demonstrate how statements about any text subvert their own meanings.
Although Derrida himself denied that it was a method or school or doctrine of philosophy (or indeed anything outside of reading the text itself), the term has been used by others to describe Derrida's particular methods of textual criticism, which involved discovering, recognizing and understanding the underlying assumptions (unspoken and implicit), ideas and frameworks that form the basis for thought and belief.
Deconstructionism is notoriously difficult to define or summarize, and many attempts to explain it in a straight-forward, understandable way have been academically criticized for being too removed from the original texts, and even contradictory to the concepts of Deconstructionism. Some critics have gone so far as to claim that Deconstruction is a dangerous form of Nihilism, leading to the destruction of Western scientific and ethical values, and it has been seized upon by some conservative and libertarian writers as a central example of what is wrong with modern academia. Richard Rorty (1931 - 2007) has attempted to define Deconstruction as the way in which the "accidental" (or incidental) features of a text can be seen as betraying or subverting its essential message.
Major influences on Derrida's thinking were the Phenomenologists Edmund Husserl and Martin Heidegger, although mainly in a negative sense (Derrida's early work was mainly an elaborate critique of the limitations of Phenomenology). He also claimed that Friedrich Nietzsche was a forerunner of Deconstruction in form and substance.
The development of Deconstructionism mainly took place at Yale University between the 1960s and 1980s, in a climate heavily influenced by the contemporaneous development of Structuralism and Post-Structuralism. In addition to Derrida, other Yale philosophers who had a hand in the development of Deconstructionism include Paul de Man (1919 - 1983), Geoffrey Hartman (1929 - ), and J. Hillis Miller (1928 - ).