Saving Isaiah.

Isaiah Berlin: A Life, by Michael Ignatieff (Holt, 480 pp., $30)

As a teacher of the history of ideas, Isaiah Berlin was lovable and beloved, dominating the spires of the University of Oxford for more than 60 years. He gave a helping hand to thousands of young students over the decades as they began their careers, including this reviewer.

As a scholar, however, he was widely dismissed by detractors as merely charming and superficially brilliant, without any deep lessons to impart. Among his intellectual peers he was commonly thought to have produced no lasting written work of serious length. But when his essays and other writings were finally systematically gathered by his editor, Henry Hardy, it turned out he had been energetic and prolific after all. One anthology of his essays, published last year, runs to 634 pages. In all, seven volumes of his collected essays have been published so far.

The strand of thought that tied Berlin's diverse interests together was the need to protect human diversity and freedom from the totalitarian compulsion to employ coercion and political action to create Utopia. In his classic 1958 essay (originally delivered as a lecture) "Two Concepts of Liberty," Berlin argued that con- flict was inevitable in politics, because the goals of the individual and the goals of the group would always diverge. In the words of his present biographer, Michael Ignatieff, Berlin "viewed human beings as divided creatures, often required to choose between private and public claims, between reason and emotion and, crucially, between conflicting political values."

Berlin parted from Aristotle and from all thinkers of the Left in his conviction that participation in politics and the exercise of citizenship did not serve to improve human character. For this reason, he presciently warned that the triumph of "national liberation movements" in what was then coming to be called the "Third World" would not necessarily-or even probably-contribute to the individual liberty and happiness of the populations so "liberated."

Instead, Berlin drew a new distinction between the "positive" and "negative" concepts of liberty. "Positive" concepts of liberty such as classical republicanism and Marxism promised to improve permanently the human condition when they were fully implemented. But it was the more modest, but far more practical, "negative" liberties that truly guaranteed rights of expression, religious and political practice, and legal protection, Berlin argued.

Like Saint Paul in his letters and the gloomy rationalists who wrote the Federalist Papers, Berlin believed that man was fallible and fated to be permanently imperfect. "If, as I believe, the ends of men are many, and not all of them are in principle compatible with each other, then the possibility of conflict-and of tragedy-can never wholly be eliminated from human life, either personal or social," he wrote.

This short, ugly (according to his own estimation), fast-talking Latvian-born Jew gave the lie to the pseudo-rational Enlightenment doctrine of Immanuel Kant that it was possible to create a utopian society in which human beings would always choose the "rational" life. Although personally a New Deal liberal, Berlin knew Kant's real insight was his despairing admission that "out of the crooked timber of humanity, no straight thing was ever made."

Berlin's celebration of the inevitability of choice and conflict in human decision-making ran counter to one of the dominant themes in human thought for more than two millennia: the delusion-inherent in Plato's Republic, revitalized and romanticized by Jean- Jacques Rousseau, and beloved of totalitarians ever since-that the happiness of mankind and the perfection of human society can be achieved by political means.

Political philosophers grounded in the reality of human experience have rejected that delusion for a very long time. But Berlin went farther. He argued that the very attempt to produce any earthly utopia-whether of the Right or the Left-would automatically lead, not to the establishment of Heaven on earth, but of Hell. Everything we have witnessed this century bears out that thesis.

Realists who confront the mortal limits of human nature are supposed to be glum, but Berlin was a joyous soul. Meeting him invariably brought to mind Winston Churchill's memorable comment that any meeting with Franklin Roosevelt was like uncorking a bottle of champagne. In Michael Ignatieff's book, this great and good man is celebrated, and his lessons for the ages taught anew.

Mr. Sieff is State Department correspondent for the Washington Times.