British Knights of the Open Society. Sir Isaiah Berlin, Sir Karl Popper and a Cup of Pluralism

In the winter of 1937, two young émigrés joined by a British colleague met for tea at a Lyons' Corner House in London. One was a Viennese schoolteacher on his way to a junior lectureship at what his wife later called "halfway to the moon," the University of Canterbury in Christchurch, New Zealand. The other was a Latvian-born Fellow of All Souls, elected at twenty-three, the first unconverted Jew in the college's five-hundred-year history. The third was A.J. Ayer, just then on the verge of publishing the manifesto of British logical positivism. Isaiah Berlin later recalled the occasion with characteristic understatement: "Freddie and I gave him tea and I thought he was a very nice, interesting man" (Gavriel Cohen, Conversations with Isaiah Berlin, No. 6, 10 December 1987). The interesting man was Karl Popper.

Within eight years, working from opposite ends of the earth, both would produce works that permanently altered the philosophy of freedom. They would be knighted by the same Crown, honoured by the same academies, and buried within the same decade. They never became close. They never quite agreed. And they may have needed each other more than either was willing to admit.

The parallels are almost too neat. Popper spent the war years in New Zealand, his wife Hennie stretching their income on what she described to E.H. Gombrich as a "carrot and rice diet, for economy's sake," while he filled aerogramme after aerogramme to London begging Gombrich to find a publisher for a seven-hundred-page manuscript on Plato, Hegel, and Marx. The manuscript, originally titled "A Social Philosophy for Everyman," was rejected by publisher after publisher. Cambridge University Press declined it on the extraordinary grounds that "a university press ought not to publish a book that is so disrespectful of Plato" (Gombrich to Popper, 13 October 1943; quoted in Hacohen, Karl Popper: The Formative Years, 2000, p. 457). Only through Gombrich's tenacity and Friedrich Hayek's intervention at Routledge did the book appear, in 1945, as The Open Society and Its Enemies. Berlin, meanwhile, was drafting weekly political summaries at the British Embassy in Washington so lucid that Churchill read them personally (and we can enjoy them today as well). Berlin would not produce his masterpiece until 1958, when he delivered "Two Concepts of Liberty" as his inaugural lecture at Oxford, but his 1939 Karl Marx already contained the instincts that would define his life's work: a deep suspicion of any doctrine claiming to decode the laws of history.

When Berlin read The Open Society, he called it the work of a thinker who had produced "the most scrupulous and formidable criticism of the philosophical and historical doctrines of Marxism by any living writer" (quoted in Magee, Popper, 1973). The praise was genuine. Both men had spent their youth watching the same catastrophe unfold from different vantage points: the seduction of closed systems, the promise that history could be mastered if only the right class or race or party seized the wheel. Popper had flirted with Marxism at seventeen and renounced it after a Vienna street demonstration in 1919 turned bloody. Berlin had witnessed both Russian Revolutions as a boy in Petrograd, watching a tsarist policeman dragged away by a mob, an image that haunted him for life.

They arrived at the same conclusion by different routes: the deadliest political ideas are not the ones that sound wicked, they are the ones that sound perfect.

They arrived at the same conclusion by different routes: the deadliest political ideas are not the ones that sound wicked, they are the ones that sound perfect.

What they shared, at bottom, was an attack on what Berlin called "monism," the conviction that all genuine human questions have a single correct answer, that the correct answers form a harmonious whole, and that some method exists for discovering them. Accept this, and politics becomes engineering.

Dissent becomes pathology. Popper traced the pattern from Plato's philosopher-kings through Marx's classless society. "We must not argue," he wrote, "that the misery of one generation may be considered as a mere means to the end of securing the lasting happiness of some later generation or generations" (Conjectures and Refutations, 1963, p. 362). Berlin approached the same problem from the history of ideas, finding evidence that human goods are plural, that liberty and equality cannot both be maximized at once, and that the collision of real values is a condition to be endured rather than a problem to be solved. "The world we encounter in ordinary experience," he wrote, "is one in which we are faced with choices between ends equally ultimate, and claims equally absolute, the realisation of some of which must inevitably involve the sacrifice of others" ("Two Concepts of Liberty," 1958).

The difference between them is what makes reading them together worthwhile. In February 1959, Popper wrote Berlin a remarkable letter about "Two Concepts." He opened with praise so warm it was almost disarming: "I have hardly ever read anything on the philosophy of politics with which I agreed so completely on all important issues" (Popper to Berlin, 17 February 1959; in After The Open Society, ed. Shearmur and Turner, 2008).

Then he turned critical. Berlin had characterized the Enlightenment's rationalist tradition as dangerously monist, a line of thought running from Plato through the philosophes to the totalitarians. Popper objected. He was a rationalist. He had spent his life defending Kant's sapere aude dare to know. He did not recognize himself in Berlin's portrait. "What have you against sapere aude?" he asked. Berlin's reply, a month later, was careful. The whole of his lecture, he explained, was "an attempt at a brief study, or prolegomenon to the study, of the way in which innocent or virtuous or truly liberating ideas (know thyself or sapere aude or the man who is free although he is a slave, in prison etc.) tend (not inevitably!) to become authoritarian and despotic and lead to enslavement and slaughter when they are isolated and driven ahead by themselves" (Berlin to Popper, 16 March 1959; in Enlightening: Letters 1946–1960, ed. Hardy and Holmes, 2009).

Here is the crux. Popper believed that reason, properly understood as the willingness to submit one's beliefs to criticism, is the best available guard against tyranny. Berlin believed that reason, improperly deified, has itself been the pretext for tyranny. Both were right. The tension between them is not a contradiction. It is a productive double exposure. Popper's most compressed formulation came in a follow-up letter: "Science has no authority; it can claim no authority. Those who claim authority for science, or in the name of science, misunderstand science" (Popper to Berlin, 21 March 1959). Science without scientism. Reason without rationalism. The open society defends inquiry and refuses worship.

Henryk Skolimowski, who knew both men at Oxford in the early 1960s, left the sharpest sketch of their contrasting temperaments: "Popper's intellect was penetrating while Berlin's mind was scintillating. Popper drilled with an amazing single-mindedness. Berlin continually burst with ever new effervescent flowers. With Popper you always discussed his ideas. You were for him. Berlin was always for you, generous to a fault" ("Karl Popper and Isaiah Berlin," c. 1998).

The contrast was not merely temperamental. Popper's pluralism, insofar as he had one, was epistemic: because we can never be certain we possess the truth, we must keep the channels of criticism open. Berlin's pluralism was ontological: human values themselves conflict, not because we are ignorant but because that is the nature of moral life. Popper gives us a method for living with uncertainty. Berlin gives us a reason why the uncertainty will never end.

Popper's pluralism, insofar as he had one, was epistemic: because we can never be certain we possess the truth, we must keep the channels of criticism open. Berlin's pluralism was ontological: human values themselves conflict, not because we are ignorant but because that is the nature of moral life. Popper gives us a method for living with uncertainty. Berlin gives us a reason why the uncertainty will never end.

Britain made both of them possible. The country that sheltered Popper and Berlin also sheltered Hayek and Gombrich, Wittgenstein and Namier, Pevsner and the entire Warburg Institute library, sixty thousand volumes loaded into two small steamers, the Hermia and the Jessica, in Hamburg in December 1933 and floated quietly down the Elbe to safety in London.

What Britain offered was a particular intellectual culture, empiricist, sceptical of grand systems, hospitable to argument. Oxford trained Berlin in the Greats tradition, whose premise was that one could read Thucydides in the morning and legislate in the afternoon. LSE gave Popper a department he named, with characteristic precision, the Department of Philosophy, Logic and Scientific Method. In 1952, hundreds of thousands of listeners tuned in each week to the BBC Third Programme to hear Berlin lecture on six enemies of human liberty.

Bryan Magee's televised conversations with Popper in 1978 reached a similar national audience. A culture that knights its philosophers is telling you something about what it values.

Ralf Dahrendorf, himself a refugee who would later direct LSE and become a peer of the British realm, called Popper, Berlin, and Raymond Aron his "fatherly friends" and designated them Erasmier, twentieth-century Erasmians, exemplars of a liberal spirit defined by the courage of solitary struggle for truth, the justice of living with contradictions, the discipline of engaged observation, and the wisdom of passionate reason (Versuchungen der Unfreiheit, 2006).

Erasmians do not resolve tensions. They inhabit them.

Today both thinkers are simultaneously invoked and misread. Popper's paradox of tolerance circulates as a meme stripped of its most important qualification: he wrote, in the same footnote, that "as long as we can counter them by rational argument and keep them in check by public opinion, suppression would certainly be most unwise" (The Open Society and Its Enemies, Vol. 1, Ch. 7, note 4). Berlin's value pluralism gets flattened into relativism, when he in fact spent decades insisting on the difference. Relativism says your values are yours and mine are mine and there is nothing more to discuss. Pluralism says there are many ways to live a fully human life, that they are not all compatible, and that choosing among them demands judgment, sacrifice, and the willingness to defend one's choices without claiming they were ordained by heaven. Berlin quoted Schumpeter approvingly: "To realise the relative validity of one's convictions and yet stand for them unflinchingly is what distinguishes a civilised man from a barbarian" (Capitalism, Socialism and Democracy, 1942; in "Two Concepts of Liberty").

Berlin quoted Schumpeter approvingly: "To realise the relative validity of one's convictions and yet stand for them unflinchingly is what distinguishes a civilised man from a barbarian"

What the two knights offer together is what neither offers alone: pluralism with spine. Popper contributes the spine, the insistence that open societies must defend themselves, that rational criticism is the engine of progress, that the answer to bad arguments is better arguments. Berlin contributes the humility, the recognition that our deepest values will sometimes collide, that no political arrangement can honour all of them at once, that the desire for a final solution to the problems of human coexistence is itself the most dangerous of political fantasies. The synthesis is unstable, even uncomfortable. That is the point. It mirrors the actual condition of free citizens trying to live together without pretending to agree about everything.

The relevance now is sharper than it has been in fifty years. We live in a moment when both populists and progressives are drifting towards polarization, in their different ways, have grown comfortable claiming privileged access to the true direction of history. Berlin and Popper warned, from inside the Vienna of 1919 and the Petrograd of 1917, against exactly this. The warning has not aged. The political technologies have.

Today the closed society does not always look like a marching column. It looks like an algorithm that decides which arguments deserve to be heard, a vocabulary so policed that disagreement becomes inadmissible before it becomes illegal, a politics that confuses moral seriousness with intolerance of dissent. Popper would recognize the pattern. So would Berlin.

Today the closed society does not always look like a marching column. It looks like an algorithm that decides which arguments deserve to be heard, a vocabulary so policed that disagreement becomes inadmissible before it becomes illegal, a politics that confuses moral seriousness with intolerance of dissent. Popper would recognize the pattern. So would Berlin.

What is left of them, then, is more than slogans. Berlin's "crooked timber" has become a motto, Popper's "open society" a brand. The substance is harder to keep. The substance is the refusal of two specific certainties: that history has a direction we can read off, and that human values can be harmonized by sufficiently intelligent rulers. Strip those away, and what remains is the Socratic wager that conversation, even difficult conversation, is preferable to silence, and immeasurably preferable to force.

The crooked timber of humanity, Kant observed, will never yield a straight thing.

Berlin adopted the phrase as a motto. Popper's version was plainer but no less honest: "I may be wrong and you may be right, and by an effort, we may get nearer to the truth" (The Open Society and Its Enemies, Vol. 2, Ch. 24). Two men. Two temperaments. One wager, placed on the possibility that free people, arguing openly, will do less harm than any alternative yet devised.

In an age addicted to certainty, on the right and on the left alike, that wager still looks like the best one available. The knighthoods were earned. Their arguments still unfinished. ◳