Derrida's writing undermines our usual ideas about texts, meanings, concepts and identities - not just in philosophy, but in other fields as well. Reactions to this have ranged from reasoned criticism to sheer abuse deconstruction has been controversial. Should it be reviled as a politically pernicious nihilism, celebrated as a philosophy of radical choice and difference ... or what? There's much more to Derrida's work than the public controversies suggest. But controversy can reveal something about what's at stake in contemporary philosophy. A small quarrel at Cambridge has done precisely that..