In Human Action--in the section entitled "A Critique of the Holistic and Metaphysical View of Society"--Mises rejects the holistic idea that "society is an entity living its own life, independent of and separate from the lives of the various individuals, acting on its own behalf and aiming at its own ends which are different from the ends sought by the individuals" (third revised edition, 1966, p. 145). He sees the classical liberal break from this collectivist notion as expressing an Epicurean view of the world:
The historical role of the theory of the division of labor as elaborated by British political economy from Hume to Ricardo consisted in the complete demolition of all metaphysical doctrines concerning the origin and the operation of social cooperation. It consummated the spiritual, moral, and intellectual emancipation of mankind inaugurated by the philosophy of Epicureanism. It substituted an autonomous rational morality for the heteronomous and intuitionist ethics of older days. Law and legality, the moral code and social institutions are no longer revered as unfathomable decrees of Heaven. They are of human origin, and the only yardstick that must be applied to them is that of expediency with regard to human welfare. The utilitarian economist does not say: Fiat justitia, pereat mundus [let justice be done, though the world perish]. He says: Fiat justitia, ne pereat mundus [let justice be done, so the world does not perish]. He does not ask a man to renounce his well-being for the benefit of society. He advises him to recognize what his rightly understood interests are. In his eyes God's magnificence does not manifest itself in busy interference with sundry affairs of princes and politicians, but in endowing his creatures with reason and the urge toward the pursuit of happiness. (p. 147)Elsewhere in Human Action, Mises adopts an Epicurean eudaimonism in his "praxeology"--his explanation of human action as purposive behavior--in presenting all human action as directed to removing uneasiness and thus pursuing happiness. The end of human action is that Epicurean tranquility of mind understood as "that state of perfect happiness and contentment at which all human activity aims without ever wholly attaining" (p. 15).
In contrast to the "holistic and metaphysical view of society," the Epicurean liberal sees social order not as an intelligently designed imposition by the state conforming to some cosmic or theological conception of the Good, but as an evolved order of spontaneous rules devised by individuals acting for their own ends. That spontaneous moral order arises through a tacit agreement to cooperation for mutual benefit, which is elaborated in modern social contract theory. This idea was anticipated by Epicurus: "Natural justice is a pledge of reciprocal usefulness, that is, neither to harm one another nor be harmed" (5.xxxi).
In embracing this Epicurean utilitarian hedonism, Mises argued against the tradition of natural law, which provoked Murray Rothbard into defending a natural law or natural rights basis for classical liberalism. But I think Mises and Rothbard were not really so far apart on this issue, because Mises recognized that what human beings regard as "useful" reflects the natural desires of their evolved human nature. In appealing to the human nature of social cooperation, Mises was implicitly appealing to a natural law/natural rights conception (see, for example, Socialism, 356-363, 408-409).
That Epicurean philosophy supports modern classical liberalism is also suggested by Leo Strauss. In his book Liberalism: Ancient & Modern, the central chapter and the longest chapter is his "Notes on Lucretius," thus implying that the Epicureanism of Lucretius anticipates modern liberalism. Strauss was famous for stressing the "quarrel between the ancients and the moderns." But in the Preface of this book, Strauss noted the modernity of ancient Epicureanism:
The most extensive discussion is devoted to Lucretius' poem. In that poem, not to say in Epicureanism generally, premodern thought seems to come closer to modern thought than anywhere else. No premodern writer seems to have been as deeply moved as Lucretius was by the thought that nothing lovable is eternal or sempiternal or deathless, or that the eternal is not lovable. Apart from this, it may suffice here to refer to Kant's presentation of Epicureanism as identical with the spirit of modern natural science prior to the subjection of that science to the critique of pure reason. (viii)And yet, Strauss worries about the sadness of this Epicurean teaching--that the world that we love is not eternal, because every world is mortal within the eternal universe of atoms in motion. He identifies this as "the most terrible truth" (85, 100, 135). Philosophers can live with this truth with a tranquil mind. But most human beings cannot. And consequently most human beings can find peace of mind only through the "pleasing delusion" of a religious belief that the world of human concern is supported by a loving intelligent designer.
Here is where Strauss and the Straussians depart from Lucretian Epicurean science. Following the Nietzsche of his early and late writings, they look to a new religion--perhaps even an atheistic religiosity--that will hide the "deadly truth" of modern science, and especially Darwinian science. They thus reject the Epicurean and Darwinian liberalism of Nietzsche's middle writings--Human, All Too Human and Dawn. Strauss implied this in his essay on Beyond Good and Evil by emphasizing the importance of Nietzsche's affirmation of "the eternal basic text of Homo natura": Strauss and Nietzsche long for eternity rather than evolution.
This explains why so many of the Straussians--for example, Leon Kass--show such a deep fear of modern evolutionary science and such a deep longing for a new religion to support an intelligent-design cosmology.