My definition of Derrida: Jacques Derrida was a very revolutionary man.  He introduced the world to Deconstructionism - a wild beast in and of itself.  Derrida's deconstructionism is concerned with the break down of literary texts through the use of language.  He, like Paul de Man, was concerned with the instability of language as related to signifiers and signified.  This can be seen in his investigation of the word pharmakon in his essay "Plato's Pharmacy."  Pharmakon can mean either drug or remedy.    For Derrida, there was no truth behind languge.  Many languages have tried to present a truth behind languague but failed.  Derrida rejected New Criticism due to its narrow view of text.  For Derrida, there was nothing outside of the text.  Everything is a text.  The things one brings to a text become part of the text.  Derrida also believed that we must overturn major binaries (phonocentric traditions in Western metaphysics) because we can - not because we have to or because the underdog is king - because we have to.  Born a Frenchman in Algeria, he was a pied-noir like one of his existentialist heros, Camus.  Derrida explores the relationship between life and writing in his work.  He was awed by the existentialists: Kierkegaard, Heidegger, and Husserl especially.  Derrida also had a fondness for that great deconstructor of language, James Joyce.