The conventional recent history of Anglophone normative political philosophy, which credits John Rawls's publication of A Theory of Justice (1971) with its rebirth, is unfair to those important figures who came before Rawls—chiefly Karl Popper, Michael Oakeshott, F.A. Hayek, and—the subject of this critical introduction—Isaiah Berlin. There is a further irony in that what can be clearly identified as the major theme of Berlin's lifework—moral pluralism—also dominates the late writings of John Rawls and those influenced by him. Indeed, it is arguable that the intense interest displayed in Berlin's account of pluralism owes much to the importance of this topic in contemporary moral and political philosophy. To some extent, even the Berlin of the classic and influential lecture “Two Concepts of Liberty”—which has for long constituted the inescapable starting point for any serious analysis of this ideal—is overshadowed by the Berlin who insists that the goods human beings pursue are inescapably plural, conflicting, and incommensurable.

Berlin has been well served by the indefatigable and diligent efforts of his editor, Henry Hardy. He is well served here in this excellent book by his commentator, George Crowder. Crowder does a marvelous job of identifying the principal themes in Berlin's work, explaining Berlin's motivations, correcting prevalent misunderstandings, and responding on his subject's behalf to important criticisms. Even where Crowder identifies indictable silences on Berlin's part—his saying little or nothing, for instance, about social justice and cultural pluralism—he suggests what Berlin could, and should, have said about matters.

Crowder's achievement is remarkable when one considers a number of salient facts. First, Berlin was chiefly an essayist. His command of his material was impressive and he wrote—as he spoke—at an exhilarating gallop, covering huge tracts of intellectual territory with verve and swagger. Yet he penned no single magnum opus, no defining text to encapsulate his political vision. Second, Berlin's distinctive approach combines both analysis and the history of ideas. Yet his analysis disappoints those who detect lack of clarity and imprecision, and his history irritates exegetes who accuse him of oversimplification. Third, he is accounted a liberal yet, as Crowder notes, he rarely identified or specified his liberal views. Fourth, he is accounted a political philosopher, yet he wrote little on the topics that preoccupy his contemporaries and engaged little with the views of his fellow philosophers, most notably John Rawls. Fifth, he had little positive to say. His was rather a vision of what could go wrong when one listened to the siren call of monism. He was happier exposing the shortcomings of his enemies than he was making clear what he shared with those on the side of the angels.

Why then is Berlin regarded as so important, and why should we continue to take him seriously? Because, as Crowder makes clear, his work is animated by the passionate conviction, persistently restated, that there is no single right answer to the moral question of how we should lead our lives, and that the political evils of the last few hundred years can be laid at the doors of those—monists—who believe otherwise. That conviction is tenaciously pursued in Berlin's attempts to understand the writings of those who can be identified as the intellectual friends and enemies of liberty. That conviction resonates with all those who can look to the real present-day world of extensive moral disagreement, the many ways humans choose to live fulfilling lives, and who can, further, now look back at the barren landscape occupied by failed attempts to build single-vision utopias.

However, what nags at Berlin's critics is a doubt as to whether his pluralism can indeed serve the cause of a liberalism that gives priority to the freedom of individuals from state coercion and social pressure to lead their lives as they, and not others, see fit. In the first place, there have been monists who espouse the cause of liberty. The utilitarian John Stuart Mill is an obvious example. Second, there is the worry—ably exploited by John Gray—that a thoroughgoing pluralism should not sustain but in fact undercut liberalism. If there are indeed many morally incomparable ways to arrange matters, why is liberalism especially privileged? Third, it is unclear why liberalism needs Berlin's meta-ethical pluralism—the view that the good is irreducibly plural—rather than simply the observable, and predictable, fact to which Rawls appeals, namely, that the citizens of a liberal democratic society will disagree fundamentally and enduringly about conceptions of the good. Fourth, it needs showing, rather than simply assuming, that freedom to choose the good life is valuable when there is no single right answer to the question of what that life is.

Crowder offers suggestions of exemplary clarity as to how one might respond on Berlin's behalf. They will persuade Berlin's critics to varying degrees. An appeal to the phenomenology of our moral experience, for instance, does not evidently speak in favor of pluralism. Indeed, the meta-ethical realist can reasonably argue that human beings dispute moral matters in the belief—if not confident expectation—that one should settle on a single right answer. Crowder is also an honest enough commentator to indicate where Berlin's views cannot easily be saved. He pulls off the trick of being a deeply sympathetic but dispassionate critic, someone attracted to the overarching vision but unprepared to serve as a naive acolyte.

The measure of Crowder's not inconsiderable achievement is thus that in respect of Berlin's writings, we can now be much clearer about what is at stake, where we are in need of further good arguments, and what lines of thinking we might profitably pursue. Berlin's vision is clearer to us both in its strengths and in its weaknesses.