Mill, Hayek, and Liberalism - by Cass Sunstein
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Mill, Hayek, and Liberalism<br>Two Routes to Freedom
Cass Sunstein<br>Aug 22, 2026
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I have spent much of the last six months with John Stuart Mill and Friedrich Hayek, two apostles of freedom.<br>The two offered two very different justifications of freedom. Their ultimate conclusions are pretty close - but intriguingly different.<br>Cass’s Substack is a reader-supported publication. To receive new posts and support my work, consider becoming a free or paid subscriber.
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Mill was a romantic about choosers (about you and me, and what we know, and what we are capable of), while Hayek was not a romantic about choosers at all (not close). He was a romantic, or something like that, about undesigned orders and traditions, and a skeptic about planners.<br>Mill put a bright spotlight on individuals, their knowledge, their potential, and their agency. Hayek put a bright spotlight on markets and traditions, and on government planners and what they cannot know.<br>Hayek was a bit obsessed with Mill, and highly critical of him. Occasionally he was even a bit nasty about him, I think. It’s a long and intriguing story.<br>I am tempted to say that Hayek was formed, in large part, by Austrian economics, fascism, communism, and socialism, and that that simple fact helps explain the difference between them. But I know that’s too simple. I am tempted to say that Mill was formed, in large part, by Harriet Taylor, and by the effect of their intense relationship, and the scandal it caused, on his life. But I know that’s too simple as well. More on this below.<br>Conclusions first.<br>Mill of course supported the Harm Principle: “The sole end for which mankind are warranted, individually or collectively, in interfering with the liberty of action of any of their number, is self-protection. That the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others."<br>Hayek did not think that the Harm Principle was far off, but he had two objections.<br>In a sense, Hayek thought that the Harm Principle would protect too much. Here Hayek distinguished his own view from Mill’s, noting that Mill “directed his heaviest attack against such ‘moral coercion.’” In Hayek’s view, Mill “probably overstated the case for liberty.” That is a wow. Hayek was not famous for complaining that people overstated the case for liberty.<br>(For Mill, it was very important that the Harm Principle extended to “moral coercion.” He was much concerned about that.)<br>Hayek also thought that the Harm Principle would protect too little. Hayek urged that Mill left the door too open to official coercion. If I don’t laugh at your jokes, have I harmed you?<br>Hayek did say that “the most conspicuous attribute of liberalism that distinguishes it as much from conservatism as from socialism is the view that moral beliefs concerning matters of conduct which do not directly interfere with the protected sphere of other persons do not justify coercion.” That sounds close to Mill, and it might even be seen as an effort to update Mill and to be more precise; “interfere with the protected sphere of other people” is more careful than “harm to others.” But the passage goes by very quickly, and there is no sustained analysis, here or anywhere else, of Mill’s account of liberty.<br>The most specific statements can be found in The Constitution of Liberty, where Hayek notes that Mill offered “a distinction between actions that affect only the acting person and those which also affect others.”<br>Hayek said that the distinction “has not proved very useful,” because “there is hardly any action that may not conceivably affect others.” If I do not buy your product, I have harmed you; if you do not like me, you have harmed me. For Hayek, the Harm Principle could be a license for all sorts of coercion.<br>Hayek urged that “the important question is whether the actions of other people that we wish to see prevented would actually interfere with the reasonable expectations of the protected person.”<br>Okay, then: instead of harm, “reasonable expectations of the protected person.”<br>That raises its own questions, of course. What are those reasonable expectations? Hayek was clear that “the pleasure or pain that may be caused by the knowledge of other people’s actions should never be regarded as a legitimate cause for coercion.” But that does not tell us how to identify “the reasonable expectations of the protected person.”<br>Hayek’s useful phrase here is “the protected sphere of other people”; that captures his alternative to the Harm Principle. But to know what that protected sphere is, we need a theory of entitlements – of rights that you have against other people. Hayek did not supply that theory, though he surely knew that he needed one. (I speculate that he would have thought that undesigned orders, and the common law, were helpful here.)<br>Now to the matter of...