With a title that echoes the ideas of Judith Shklar (but that differs significantly from her, in its breadth), Alan S. Kahan provides us with his most ambitious account of liberal political thought. As an accomplished scholar of Alexis de Tocqueville, Kahan has already made important contributions to scholarship—notably, with his 2001 book, Aristocratic Liberalism: The Social and Political Thought of Jacob Burckhardt, John Stuart Mill, and Alexis de Tocqueville. But in this most ambitious of works, he provides a comprehensive overview of liberalism, from its proto-liberal founding in Montesquieu and Adam Smith, through nineteenth-century classics from Immanuel Kant, James Madison, Benjamin Constant, and Mill to the giants of early and mid-twentieth century. It is a magnificent and grand synthesis of thinkers, concepts, ideas, and debates designed to give an overview of liberalism as an ideology, a doctrine, and a set of thinkers. But Kahan’s book also offers more than that as it positions liberalism as a vital and continuously changing contribution to thinking about the challenges of modern politics—challenges that Kahan thinks are just as salient in a world of populism and post-liberalism. Although very different in scope and ambition, this is a book that ranks alongside the work of Samuel Moyn’s 2023 Liberalism against Itself or Patrick Deneen’s 2018 Why Liberalism Failed and invites critical comparison.

Grand-narrative histories of doctrines and ideologies often invite the usual pedantic scholarly challenges about the impossibility of writing a history of a doctrine or a concept that varies and changes its shape from context to context. Is liberalism even a concept or thing with a single identity? When did it start? Was John Locke a liberal in 1688? Kahan takes all of these challenges in his stride and offers us a considered way of approaching the past from the perspective of the present. There is no real point in claiming that there is no such thing as liberalism when it has become one of the main languages of western political theoretical argument. The question is not whether such a thing exists, but when is it most fruitful to identify its origins? Kahan has an important side argument about why John Locke is not a liberal, but that we can align Montesquieu and Smith as proto-liberals. (I think he is wrong about Locke, but that is not the point.) The main point is that Kahan provides readers with a helpful theoretical framework that allows us to see the linkages and affinities between thinkers, alongside their diversity of method and approach.

This brings us to the place of fear in Kahan’s story. Judith Shklar, the late Harvard political theorist, coined the term the “Liberalism of Fear” for her limited normative defense of post-totalitarian liberalism. Kahan acknowledges Shklar’s influence in his choice of fear as a central concept, but he uses it in a very different way to periodize his account of liberalism as a doctrine. His argument is that liberal politics and ideas develop to confront the problem of fear. And they do this by varying the relationship between the three essential pillars of liberalism—namely, the idea of freedom and the interrelation between markets and morals in the defense and maintenance of freedom in the face of sources of fear.

These sources of fear, however, change over time. Consequently, Kahan argues that this gives rise to four different version of liberalism, which he helpfully identifies as if they are different operating systems: Liberalism 1.0 to Liberalism 4.0. (An appendix on page 451 helpfully lists and illustrates these distinctions.) After a brief discussion of the proto-liberalism of Montesquieu and Smith, Kahan contends that Liberalism 1.0 arises in the context of the fear of revolution, specifically in reaction to the American and French revolutions. This version of liberalism includes Madison, Kant, Constant, Tocqueville, and Mill as well as underrated thinkers such as T. B. Macauley and thinkers like Jeremy Bentham who are often cast into the world of anti-liberals. With the death of Mill, we move to Liberalism 2.0, where the motivating fear is now the social threat of poverty. This fear results in classical liberals veering in an anti-statist direction as the state seeks more powers or in another direction where modern liberalism supports the state to help overcome the threat that poverty poses to personal freedom. Such a version is successful until the collapse of liberal optimism in the post WW1 world. From then until the end of the Cold War, Kahan argues, Liberalism 3.0 positions itself against the threat posed by the rise of ideological and movement politics that increases with a mobilized war-time state.

The final version, Liberalism 4.0, is the liberalism of the present, where the primary threat is populism and its demonization of Liberalism as an elite or class theory that justifies the new meritocracy. Liberalism 4.0 is the unfinished part of this deliberately open-ended history as we cannot see where the “owl of Minerva” will take us tomorrow. Kahan clearly has the opportunity to update his own account going forward, as we see whether populism is the challenge that he thinks it is or whether the real challenge comes from somewhere else. Yet he ends the book on an optimistic note as he thinks liberals like himself will continue to explore the resources of this complex tradition to ensure freedom prevails into the future.

With a narrative of this breadth and complexity, all manner of specialists can chip in with their critiques of Kahan’s arguments against their favorite theorists or approach, just as they can challenge the history that underlies the ideological narrative. I would have been more generous than Kahan is to John Rawls, Robert Nozick, and Milton Friedman, as he does not give sufficient attention to disciplinary boundaries when it comes to explaining the absence of a serious discussion of the economy in Rawls or morality and ethics in Friedman. Philosophers in their professional capacity do philosophy, and economists do economics. Perhaps more on these thinkers’ theoretical contexts would be important with both of these examples. I also disagree with Kahan’s view that Bernard Williams is a perfectionist, although I can see some route to that claim. But a lack of space can excuse some disputes, and the generosity of readers will overlook other more nuanced observations in favor of the main narrative in this magnificent work.

Where I am most skeptical is with the claim that Liberalism 3.0 has come to an end and that populism requires a Liberalism 4.0. Populism is undoubtedly an issue, but is it as pressing as Kahan presents it? Many post-liberal theorists like Patrick Deneen, John Milbank, or Adrian Pabst draw on populist politics to reinforce their original communitarianism and common-good politics. It is too simple to dust off Rawls to confront these post-liberal critiques, but it is also not obvious that the post-war theory of Liberalism 3.0 does not have the philosophical resources to deal with populism as a theoretical challenge, even if the “philosophers” are light on social theory. The risk of state overreach and authoritarianism today is certainly an issue that takes us back to the liberalism of fear of Judith Shklar. What remains a challenge for all variants of liberalism is the reconciliation of liberalism as a political theory with substantive moral commitments to the good life. In Kahan’s book, the debate continues between political liberals, comprehensive liberals, and perfectionist liberals, and he concludes by advocating a return to perfectionism. In this, Kahan joins Samuel Moyn, among others. But my money remains on the side of political liberalism and the hope for a convergence on a thin conception of the good that can be shared by those of differing values.