“In accordance with the teaching of Aristotle, Aquinas maintained, not only that society in general is natural to man, but that organized political or civil society is a natural society. … But, if society is a natural institution, so also is organized government a natural institution. Even if men never sinned, there would still be need for some control over their activities directed to the common good. In short, a civil society and civil government are natural institutions in the sense that they are necessary for the fulfillment of men’s natural needs and for the leading of a full human life: there is [pace St. Augustine] no essential connexion between the State and sin, and man would still have required the State even if he had never fallen. Further, if the State is a natural institution, it is willed by God, the Author of nature.
“St. Thomas followed the Aristotelian conception of the State, in distinction from the family, as a self-sufficing community, that is, as a society which possesses in itself all the means requisite for attaining its end, which in this case is the common good of the citizens. By ‘common good’, he did not mean simply their temporal welfare in the material sense, but, more fully, the leading of a good life, which is defined, in Aristotelian fashion, as a life according to virtue. But, though he held that the State is a self-sufficing or ‘perfect’ community, he was, unlike Aristotle, a Christian; and he believed that the Church is also a perfect, a self-sufficing community, possessing in itself all the means requisite for attaining its supernatural end, the eternal happiness of its members in the beatific vision of God. At first sight it might appear that Aquinas would go on to say that the State exists to secure the attainment of man’s temporal final end, while the Church exists to secure the attainment of man’s supernatural final end. But he could not say precisely this; for he was convinced, as a Christian, that man has only one final end, a supernatural one. He held, indeed, that the State has its own sphere (otherwise it could not possibly be a ‘perfect’ community)…. On the one hand Thomas’s Aristotelianism rendered any complete subordination of the State to the Church … quite foreign to his thought. On the other hand, if man has one final end, a supernatural end, it follows that the Church is a superior society. The State is a natural institution, possessing its own sphere, the common good in the temporal order; but there cannot be a complete and absolute separation between the sphere of the State and that of the Church, since man has been placed in this world to secure a supernatural end; and his temporal life must be directed to that end. The Church is, therefore, superior in dignity to the State; and if any clash occurs between man’s supernatural interests and what appear to be his temporal interests, the latter must be subordinated to the former.”
–– F.C. Copleston, SJ, Medieval Philosophy (New York: Harper & Row,  1961, pp. 168–170, emphasis added).
The common good, which is the perfection of the universal human nature, requires the State to provide enough temporal stability that the goods of human nature are easily achievable. In that sense, radical individualism is an ideological obstruction to human flourishing. Or…?