John Stuart Mill is a champion of liberty who today lacks sufficient liberal champions of his own. Erstwhile liberals have moved progressively forward to a world where restrictions on speech seem more to be the justified norm than the barely defensible exception. Political speech is limited if officials think it to be excessively coordinated with similar speech, or if it is funded by sources they do not like. Economic speech is subject to often arbitrary regulations about insider trading. The university subjects itself and the rest of us to subtle and not so subtle rules about political correctness and offensive speech. Privacy is challenged in the name of security, or through today’s almost inescapable means of communication.

So many of these restrictions are supported by today’s Progressives that Mill, who would have questioned the substance and purpose of several of them, cannot be their hero. Even his feminism is presumably a bit too individualistic for their taste: he hardly sees women as a class of never-ending victims in a never-ending war.

The conservatives and libertarians who most object to the direction that liberals have taken, and to the fears of risk and competition that stoke liberal sensitivities today, also do not in general look to Mill for sustenance. He is, after all, no great friend of every element of capitalism, no supporter of natural rights, and no proponent of traditional virtues. For conservatives as well as Progressives he is a source of occasional quotations, not a consistent guide. Even the occasional alliances of privacy-loving libertarians with corporate-hating populists are not cemented on Mill’s principles.

He has therefore been sidelined in today’s political debates, and of his philosophical works, it is largely only On Liberty (1859)—“in many ways his finest book” in Friedrich Hayek’s view—that is read. There is something about Mill’s defense of liberty and his understanding of happiness that has gone out of fashion; even those who bemoan his inadequacies see this as not a good thing.

Friedrich Hayek’s edition of Mill’s letters to and from Harriet Taylor—whom he married after her husband’s death and with whom he had a close intellectual collaboration almost from the moment they met in their early twenties, in 1830—is interesting for what it tells us about Mill, and also what it teaches about Hayek, about contemporary economics, and about contemporary economic scholarship. Hayek placed his own important work in a larger political, moral, and historical context—a context that he examined substantively and did not simply take for granted.

Who today thinks in such a capacious manner? Almost all economists are narrow specialists whose research displays little grasp of the meaning of their own field, let alone of politics or political economy generally. Many, indeed, specialize not in economics per se but in behavioral economics, a social science of the sort whose limits were clarified over 50 years ago by political scientists. Those who are concerned with politics have narrow views of justice that they hold for reasons no better thought through than the opinions of journalists, political partisans, or other academics. Economic history is no longer a study of origins that uncovers the basic issues and disputes at stake in founding movements, disciplines, and regimes, and, therefore, the justification for them. Rather, it is now primarily a series of examples or sets of data that happen to be old rather than new.

Hayek, as we mentioned, always considered economic life in a wider framework. The present book is Volume 16 in his 19 volume collected works, published by the University of Chicago Press, books that include The Road to Serfdom (1944) and The Constitution of Liberty (1960) as well as his work on business cycles and other economic matters. In the present case, the editor, Sandra Peart, has republished Hayek’s pioneering edition of the Mill-Taylor correspondence, which presents the letters interwoven with Hayek’s brief presentations of biographical context, and has added to them his various short writings about Mill. The republished correspondence makes up two thirds of the volume.

The editor notes Hayek’s own collecting and editing skills: his work preceded and to a degree inspired the University of Toronto’s edition of Mill’s collected works (and the complete works of Harriet Taylor Mill). She writes that, since Hayek “worked with such an extraordinary amount of unpublished material containing multiple types of handwriting, as well as an enormous library of published secondary sources, the small number of mistakes is absolutely astounding.”

One advantage of Mill’s thought is the engaged curiosity from which it emerges. He was, Hayek tells us, “not merely the heir . . . of a set of ideas which were in the ascendancy.” He was also “capable of absorbing and learning from most of the other worthwhile ideas of his age.” While he began “as the product and most faithful disciple of his father who was the most active and forceful expositor of Benthamite utilitarianism,” by the age of 22, Mill had declared his independence as a thinker.

Continues Hayek:

Though utilitarianism would continue to provide the overall mental framework of his thought, Mill incorporated into it suggestions derived from Saint-Simonian socialism and Comtean positivism over the following years. These elements were derived from Burke and German idealism through Coleridge and Carlyle, much of the French liberal thought of the period leading up to the 1848 revolution and—most important for the understanding of the development of his political philosophy—Alexis de Tocqueville. To this should be added . . . Plato.

Hayek’s own concerns in this volume primarily involve liberty’s connection to private property as Mill sees it, and the degree of Mill’s attachment to versions of socialism. It is here that Hayek finds Taylor’s influence to be pernicious. On the question of the equality of women, however, where Taylor’s influence is sometimes thought to be decisive, Mill’s own statement in his Autobiography (1873) indicates that his position, although not the full elaboration of it that he later developed in The Subjection of Women (1869), preceded his relationship with her.

As Professor Peart makes clear, one can see from Hayek’s 1945 essay “Individualism: True and False,” among other works, that he came to believe that Mill was a rationalist in Hayek’s sense—someone who erroneously believes that one can effectively plan, direct, and design institutional structures based on the outcomes one seeks. Hayek thought, to the contrary, that no one possessed sufficient information to form or design such structures successfully. Rather, they should evolve on the basis of individual actions.

Mill did consider evidence; his views were not based on abstract quasi-mathematical deduction. Nonetheless, he thought reason could choose and control social mechanisms. This led him, in Hayek’s view, to depart from genuine individualism and to consider too favorably collectivist or socialistic solutions. For this and other reasons Hayek does not consider Mill to be a thinker of the “first rank” but, rather, one whose “masterly” exposition of opinions that are ahead of their time greatly influenced those following him who saw these views “as the next step in an already recognizable direction of progress.”

How much Mill was influenced by Taylor in this collectivist direction is a matter of debate. The letters read in large doses can be cloying, and Mill’s remarks to and about Taylor sometimes border on the obsequious or, indeed, cross the border to the land of the servile and fawning. What for others would require “both great genius & experience” can for Taylor, “Shelley & one or two others in a generation” be achieved without benefit of experience or trial. Indeed, Mill’s transports about Taylor’s extraordinary talents amuse or befuddle his friends. Hayek quotes one concerning “Mill’s hallucination as to his wife’s genius,” and reports Thomas Carlyle’s view that Mill’s ideas of her “were altogether absurd and insupportable.”

Hayek himself credits Taylor with poetic gifts and genuine talent, but he also considers her husband’s opinion uxorious. As Hayek writes (in a previously unpublished essay discovered among his son’s papers in 2008), Mill’s extraordinary praise of his stepdaughter, Helen Taylor, “goes far to solve the riddle which Mill’s relation to his wife presents. We still do not know enough about [Harriet Taylor] to say with assurance how much Mill must have overestimated her.”

But, Hayek goes on,

we know enough of [Harriet’s daughter] to be fairly certain that, although in her way quite a remarkable woman, she was nothing like as extraordinary a person as this passage [in the Autobiography] suggests. It seems to me to confirm what one would even without it be inclined to suspect: that probably by the education given him by his father in his early youth Mill’s character was so formed that he stood in need of someone whom he could adore and to whom he could ascribe all possible perfection. . . . No doubt Mrs. Mill was an unusual person. But the picture Mill has given us of her is throughout determined by his own character and tells us probably more of him than of her.

Despite the letters’ moments of excess and self-absorption, they on the whole provide a lively and thoughtful discussion of socialism, distributive justice, and several other issues. There is no reason to doubt Mill’s view of Taylor’s intellectual importance to him. He did not, after all, credit her with the scientific aspects of his Political Economy (1848), or with more than editorial changes to his Logic of the Moral Sciences (1872).

But Mill does consider On Liberty to be essentially a joint production, and thinks this as well about the heart of Political Economy, if not its technical aspects. Indeed, together with Taylor and Mill’s discussions of the status of women, it is especially their discussions of economic issues that are most interesting in the letters, and it is these that primarily concerned Hayek. As Mill says in his Autobiography,

it was chiefly her influence that gave to [Political Economy] that general tone by which it is distinguished from all previous exposition of Political Economy . . . the properly human element came from her: in all that concerned the application of philosophy to the exigencies of human society and progress, I was her pupil, alike in boldness of speculation and cautiousness of practical judgment.

Harriet Taylor’s leaning toward socialistic solutions and her faith in the possibilities of education and of rational choice were, however, clearly greater than Mill’s. He did not in the end eschew capitalism or economic competition. His openness to the ideas of others did not prevent him from going his own way.