It's not every French intellectual whose death is commemorated by an announcement from the office of Jacques Chirac, the French president. But Jacques Derrida, who died Friday at age 74, was not just any French intellectual. His work, as Mr. Chirac's office noted, was "read, discussed, and taught around the world."

Whether Mr. Derrida was also "one of the major figures in the intellectual life of our time," as Mr. Chirac's office asserted, is a point that has been fiercely contested ever since Mr. Derrida burst onto the intellectual scene in the mid-1960s.

Mr. Derrida (the name is pronounced deh-ree-DAH) was without doubt one of the most famous intellectuals of the past 40 years. His celebrity rivaled that of Jean-Paul Sartre. As the founder, honorary CEO and chief publicist for an abstruse philosophical doctrine he called "deconstruction," Mr. Derrida was celebrated and vilified in about equal measure. Academics on the lookout for a trendy intellectual and moral high-explosive tended to love Mr. Derrida. The rest of us felt...otherwise.

What is deconstruction? Mr. Derrida would never say. It was a question certain to spark his contempt and ire. He denied that deconstruction could be meaningfully defined. I think he was right about that, though not necessarily for the reasons he believed.

But even if deconstruction cannot be defined, it can be described. For one thing, deconstruction comes with a lifetime guarantee to render discussion of any subject completely unintelligible. It does this by linguistic subterfuge. One of the central slogans of deconstruction is "il n'y a pas de hors-texte," i.e., "there is nothing outside the text." (It sounds better in French.) In other words, deconstruction is an updated version of nominalism, the view that the meanings of words are completely arbitrary and that, at bottom, reality is unknowable.

Of course, if you put it as baldly as that, people will just laugh and ignore you. But if you dress up the idea in a forbidding vocabulary, full of neologisms and recondite references to philosophy, then you may have a prescription for academic stardom.

Stock in deconstruction has sagged a bit in recent years. There are basically two reasons for this. The first has to do with the late Paul de Man, the Belgian-born Yale professor of comparative literature. In addition to being one of the most prominent practitioners of deconstruction, Mr. de Man -- as was revealed in the late 1980s -- was an enthusiastic contributor to Nazi newspapers during World War II.

That discovery, and above all the flood of obscurantist mendacity disgorged by the deconstructionist brotherhood -- not least by Mr. Derrida, who was himself Jewish -- to exonerate Mr. de Man, cast a permanent shadow over deconstruction's status as a supposed instrument of intellectual liberation.

The second reason that deconstruction has lost some sheen is simply that, like any academic fashion, deconstruction's methods and vocabulary, once so novel and forbidding, have gradually become part of the common coin of academic discourse, and thus less trendy.

It is important to recognize, however, that this very process of assimilation has assured the continuing influence of deconstruction.

Once at home mostly in philosophy and literature departments, the nihilistic tenets of deconstruction have cropped up further and further afield: in departments of history, sociology, political science and architecture; in law schools and -- God help us -- business schools.

Deconstructive themes and presuppositions have increasingly become part of the general intellectual atmosphere: absorbed to such an extent that they float almost unnoticed, part of the ambient spiritual pollution of our time. Who can forget the politician who, accused of wrongdoing, said in his defense that "it all depends on what the meaning of the word 'is' is"?...