Nietzsche wrote somewhere that all philosophy is involuntary biography. It is hard to think of a philosopher of whom this is less obviously true than Isaiah Berlin. The heart of Berlin's thinking was a conception of loss. He held that the great goods of human life are rivals. To choose among them, as we must, is to forfeit something of irreplaceable value. For Berlin, the idea of a perfect world - a world without loss - was not so much unrealistic as incoherent. Much of his thought amounted to a sort of negative theodicy, in which the venerable theological enterprise of showing the evils of the world to be necessary to its perfection was turned upside down, and the very idea of perfection jettisoned as meaningless. As Berlin himself put it: "That we cannot have everything is a necessary, not a contingent truth."
Many have been disturbed by the pessimism in this vision. Yet Berlin's own life was extraordinarily fortunate. Born in Riga in 1909, he witnessed and remembered something of the Russian revolution. In England, where his family settled when he was 11, Berlin was a phenomenal success. In 1932, he became the first Jew to be elected to All Souls, and only the third ever to become a fellow of an Oxford college. During the second world war he worked in the United States for the British Information Service, a position placing him at the epicentre of the Anglo-American alliance; in 1945 he was seconded to the British Embassy in Moscow.
After the war, he made the contributions to political theory and intellectual history for which he is chiefly remembered in academic circles. In his lecture on negative and positive liberty and his essays on Machiavelli, Vico, Herder, Tolstoy and Turgenev, he pursued the theme of conflict and loss in moral and political life with a verve and humanity that gave his thought an audience beyond academe. In the mid-1960s, he became the founding father and first president of Wolfson College, Oxford. When he died in 1997, Berlin - an instinctively private man - was Britain's most celebrated public intellectual.
In the latter part of his life, as anyone who knew him can testify, Isaiah Berlin was a happy man, infectiously so. It is hard to square this playful, joyous personality with the vision imparted in so many of his writings. Berlin's view of human beings, himself included, was astonishingly unclouded by sentiment. To see others and oneself without illusions does not normally engender serenity. In Berlin's case a clear, unsparing eye and a calm heart somehow co-existed. His illusionless clarity of vision in no way dampened his natural generosity of spirit. Yet Berlin's insight into character could at times seem almost pitiless.
As Michael Ignatieff recounts Berlin's life, we see that the conjunction of an almost clairvoyant insight into other minds with calm humanity of judgement was not a natural gift but a hard-won achievement. He started life as an outsider. It was a long time before he achieved the mastery over himself and the recognition from others that he needed. Until his 40s he was the model of a bachelor don. A stance of detachment was his mode of coping with the world.
Berlin's meeting with the Russian poet, Anna Akhmatova, in Leningrad in 1945, changed all that. The conversations he had with this wilful, vatic, noble woman unblocked emotions that he had seldom indulged. We learn from Ignatieff that Berlin himself never doubted that his visit to Akhmatova was the most important event in his life.
How important is Isaiah Berlin? When they are not neglected, his contributions to political thought are commonly underrated. His own modesty about them must take some of the blame for this. He cared little for publication. Without Henry Hardy, his tireless editor, we would surely not have the nine volumes of essays in which Berlin took up, again and again, the theme of conflict and loss. It may well be the centrality of this theme in his thinking that accounts for the shallow impact that Berlin has had on liberal thought. The standard varieties of liberalism are all children of the Enlightenment. Faith in progress, confidence that most human dilemmas are soluble and the conviction that the power of reason which human beings have in common enables us to improve our condition - these Enlightenment hopes have long been central to liberal thought.
Berlin was a lifelong, steadfast champion of the values of the Enlightenment. Yet such Enlightenment hopes were not at the heart of his defence of liberal freedoms. He chose instead to ground the value of freedom in the necessity of choice among values that will always be at odds. The result is an intensely original contribution to political philosophy and this country's truest account of liberal values.
Berlin seldom spoke of the Holocaust, and never discussed the murder by the SS of several members of his family in Riga in 1941. Yet it is impossible to believe that his reworking of liberal thought was not in part a response to those terrible events. Whatever criticisms may be made of it, Berlin's liberalism - unlike the pretty harmonies of more recent academic liberals - has taken the full measure of the horrors of what he justly called "the worst century in history".
Berlin's reformulation of liberalism as a philosophy of choice and loss contains the essence of his thought. Nietzsche - one of Berlin's least favourite thinkers - may have been right after all. Even for Berlin, philosophy may finally have been involuntary autobiography. Ignatieff does not attempt to dispel the mystery that surrounds the willed serenity of Berlin's later years. Instead, by leaving the reader to ponder an enigma he does not pretend to solve, he has produced a masterpiece of contemporary biography.