Aquinas followed Aristotle in thinking about all ethical matters by reference to the question of what defines a good life, a project that in turn implicates ideas about what makes a good polity. Believing that the fundamental principles of the good are open to discovery through the application of human reason, Aquinas argued that natural law is simply knowing “what we must do and what we must avoid,” an echo, of course, of Aristotle’s naturalist virtue ethics. For Aquinas, then, the conscience of the individual takes on a most essential role, calling him to cultivate it and listen carefully for its counsel. The free exercise of conscience and private judgment are treated, as they ought to be, as antecedent to and more important than man‐​made governmental laws, which Aquinas says should not attempt to compel moral action by proscribing vicious action. Thus while Aquinas believes that the law should seek to promote the common good, it should never undertake to supersede the private evaluations of individual judgment. Finding the mental or literal space for such quiet contemplation today is often exceedingly difficult. What’s more, we live in a world where the modern total state has systematically eroded the foundation of trust and confidence that people once had in their families, friends, and local communities, all these being rivals to the preeminent authority of the welfare state. Even with, for example, social media and our pretensions to connectedness through technology, it may well be that we are today more socially isolated than ever before, more atomistic and wanting for a deeply meaningful social existence. Aquinas understood what so few public figures—be they intellectuals or politicians—fully grasp today, that attempts to address questions of the political kind without first striving to understand “what human beings are and how and why they act” 1 would prove an exercise in futility. Today’s political institutions and their effects on society bear out the dire consequences of disregarding human nature or thinking that it can be remade or transcended by positive law.

Aquinas contended that we should endeavor to craft human law so as to make it accord with natural law, yielding a framework conducive to living well, that is, in harmony with others and with the requirements of virtue. He would not be surprised that the contraction of the sphere of private life—those few decisions left free from the creeping encroachment of centralized control—would be accompanied by a deterioration in general virtue. To fulfill his potential as a moral, reasoning being, an individual must be free to live his life according to the values he has chosen through the deliberations of his own conscience. “[H]uman law,” Aquinas taught, “does not put forward precepts about anything other than acts of justice.” Aquinas recommended a notion of justice and the common good nothing like the one endorsed by modern governments. Shortsighted and arrogant, the cradle‐​to‐​grave managerial state has seen fit to substitute legal positivism and a counterfeit devotion to the scientific method for the individual conscience. Extensive hearings that include testimony from ostensible experts create the semblance of respect for science and empirical data, all while individual autonomy and dignity are slowly undermined. As C.S. Lewis saw, the individual has been rendered a mere ward, a childlike dependent to whom the chance for genuine thriving is denied under a pretext of protection.

In reserving a central place in political and social life for individual conscience and action, Aquinas’s work features the principle of subsidiarity, the decentralist idea (generally associated with Catholic social thought, and very often with the distributist writings of Hilaire Belloc and G.K. Chesterton) that, ceteris paribus, the sovereignty and authority of smaller units ought to be preserved, to take precedence over that of larger bodies, power being devolved as far as is possible. Religious associations and connotations aside, the principle of subsidiarity as discussed in Aquinas’s work has important consequences for a thoroughgoing libertarian critique of contemporary politics and economics. The relationship of vertical federalism that the Constitution establishes between the federal government and the various state governments is itself an example of subsidiarity, as is the relationship between the European Union as such and the member state signatories that constitute it. Indeed, the Maastricht Treaty explicitly refers to “the principle of subsidiarity,” stating that the new Union should defer to the national, regional, and local levels. Subsidiarity is grounded in the assumption that different sizes and types of organizations meet different social, political, and economics needs. We reach both efficiency and an environment conducive to general human flourishing by respecting each unit in what we might call its “core competencies,” those activities to which its organizational size and structure are most well suited. While Aquinas accredited to the state a more extensive set of competencies than would most modern libertarians, he nevertheless understood that voluntary community groups and societies should play the primary role in building a just and proper foundation for human life. Minding the principle of subsidiarity would allow us to avoid many of the problems of centralization that were so conspicuously on display in the twentieth century; it furthermore allows the maximum space for individual experimentation and personal development, opening the way to, in the words of John Stuart Mill, “many possible independent centres of improvement.”

Aquinas’s natural law philosophy is as relevant today as it has ever been, providing the contemporary student of social and political thought with tools for a comprehensive and needed critique. Aquinas’s thought rises above the false dichotomy that drives so much of mainstream political dialogue, the mistaken idea that pits the flourishing and wellbeing of the individual against the common good. These two aspects of social life, Aquinas knew, are in fact mutually reinforcing, simply highlighting two complementary ways of looking at what is right or virtuous more generally. A revival of Thomistic philosophy offers a promising antidote to the stale political conversation obtaining in the United States today—that revival cannot come too soon.