The guiding insight of deconstruction is that every structure - be it literary, psychological, social, economic, political or religious - that organizes our experience is constituted and maintained through acts of exclusion. In the process of creating something, something else inevitably gets left out.

These exclusive structures can become repressive - and that repression comes with consequences. In a manner reminiscent of Freud, Mr. Derrida insists that what is repressed does not disappear but always returns to unsettle every construction, no matter how secure it seems.

Like Kant, Kierkegaard and Nietzsche, Mr. Derrida does argue that transparent truth and absolute values elude our grasp. This does not mean, however, that we must forsake the cognitive categories and moral principles without which we cannot live: equality and justice, generosity and friendship. Rather, it is necessary to recognize the unavoidable limitations and inherent contradictions in the ideas and norms that guide our actions, and do so in a way that keeps them open to constant questioning and continual revision. There can be no ethical action without critical reflection.

Mr. Derrida reminded us that religion does not always give clear meaning, purpose and certainty by providing secure foundations. To the contrary, the great religious traditions are profoundly disturbing because they all call certainty and security into question. Belief not tempered by doubt poses a mortal danger.

Fortunately, he also taught us that the alternative to blind belief is not simply unbelief but a different kind of belief - one that embraces uncertainty and enables us to respect others whom we do not understand. In a complex world, wisdom is knowing what we don't know so that we can keep the future open.