To the Editor:

The question of Voltaire's anti-Semitism, which is again being discussed in your pages (Letters, Aug. 12 and Aug. 26), has been an object of controversy for more than two centuries. The discussion began in Voltaire's own lifetime when Isaac de Pinto wrote to Voltaire to complain of his aspersions on the Jews. Voltaire answered that anyone could be what he pleased, even a Jew, provided he was a philosopher. This exchange has been quoted to this very day as ''proof'' that Voltaire was not an anti-Semite. He was at war with both Judaism and Christianity. He wanted to purge all men, of whatever persuasion, from these superstitions in order to make them enlightened.

In a book published more than 20 years ago, in 1968, entitled ''The French Enlightenment and the Jews,'' I argued against this construction. An anti-Semite of the most damaging kind is one who asserts that, no matter what Jews might believe, their inherent character is fixed - and nasty. In the book, I cite dozens of passages from the whole corpus of Voltaire to the very end of his life, more than a decade after he had made his brief bow to de Pinto. Two citations will suffice. In his ''Letter of Memmius to Cicero'' (1771), Voltaire, in the pose of an ancient Roman reporting on the Jews, wrote: ''They are, all of them, born with raging fanaticism in their hearts, just as the Bretons and the Germans are born with blond hair. I would not be in the least bit surprised if these people would not some day become deadly to the human race.'' In the next year, writing the essay ''One Must Take Sides'' - introduced as ''the last word by Voltaire on metaphysics'' - he ridiculed each of the major religions, but he was meanest to the Jews: ''You have surpassed all nations in impertinent fables, in bad conduct and in barbarism. You deserve to be punished, for this is your destiny.'' This is hardly the rhetoric of a man who thinks that Jews are just another people waiting to be enlightened. It is the talk of a ''noble Roman,'' his favorite self-definition, who has no patience with inferior people such as Jews and, for that matter, blacks.

The defenders of Voltaire have continued to argue that he was not personally an anti-Semite but only guilty of some rhetorical excesses. That is not how those who were arguing for and against the emancipation of the Jews, both in his own time and in the next several generations, read him. Jacobins such as Jean Francois Rewbell in the 1790's and the socialist Pierre Proudhon in the next generation are among the many figures, especially of the left, who justified their arguments against the Jews by quoting Voltaire. Such figures were not quarreling with Judaism; they were attributing innate wickedness to the Jewish character. This is racist anti-Semitism. Such opinions helped open the door to the horrors of our century.