From Citizendium, the Citizens' Compendium
He provided, along with such thinkers as Paul de Man, Michel Foucault, and Jacques Lacan, the intellectual impetus for what Anglo-American thinkers and critics later called "Deconstruction." Derrida's seminal works include Speech and Phenomena (La Voix et le phenomene, 1967), Writing and Difference (L'Ecriture et la difference, 1967), Of Grammatology (De la Grammatologie, 1967), and Dissemination (La dissemination, 1972), as well as essays in the Parisian journal Tel quel.
Despite extended engagement with philosophical forebears such as Husserl (in Speech and Phenomena), Hegel (in Writing and Difference), Rousseau (in Of Grammatology), and Plato (in Dissemination), Derrida does not attempt a comprehensive philosophical critique of these philosophers; by considering the philosophical "blind spots" these thinkers open by granting authority to certain ways of construing truth, such as preferring speech over writing or logical concept over metaphor, Derrida expounds his own philosophical position regarding the status of truth and knowledge in Western philosophy.
For Derrida, all concepts are inextricably bound up with metaphor. Any concept that understands an aspect of some thing about or in the world is thus necessarily logically invalid, ungrounded--and in that sense "false"--since it relies to some extent on an "as if" way, a metaphorical way, of understanding that thing. In other words, the very nature of logical concepts dooms them to mark out (unwittingly, so to speak) some aspect of the object they supposedly understand which escapes subsumption to that concept, escapes its understanding.
Because Derrida is saying that all truth bears falsity along with it, some have declared Derrida absurdist for supposedly claiming that truth is falsehood, but this view is ill considered. The thrust of Derrida's thought points up the contingency and constructedness of truth, not that there is no such thing as truth. Satisfied to demonstrate the contingency of truth under any and all conditions, Derrida is silent on the nature of truth's contingency. A more considered critique of Derrida's view might see his thought as a form of transcendental skepticism, not dissimilar to Kant's. In any case, via rigorous philosophical demonstration, Derrida explicates the limitations of the logical conceptual thinking one routinely employs to live the requirements and ordinary situations of everyday life.