While reading a recent article from @ccpecknold on De Koninck's contribution to the development of the concept of the common good - which I recommend - I came across the following passage which I thought was deserving of comment.

I remarked to someone earlier today that Liberalism doesn't actually have the means to understand the common good, because it can only conceive of community as an aggregate of homogeneous, autonomous individuals, of the common good as a sum total of private goods.

This radical Individualism, originally a reaction to Absolutism, is at the heart of the political and economic Liberalism we know today, whether of a "conservative" or a "progressive" bent. For either kind of Liberal, there is no common good, only overlapping private interests.

Having no real conception of the common good, the function of the Liberal State is thus limited to the protection of contractual relations between individuals, i.e., the commutative justice of the marketplace. Even marriage becomes a mere contract, to be dissolved at will.

When Liberals - whether "conservative" or "progressive" - speak of the "common good," what they mean is the benefit or advantage of a group formed via temporary alliance by virtue of their shared private interests. The result is, as was well-put above, a society of petty tyrants.

The error opposite of such Individualism is Collectivism, which views the individual not as an autonomous person, but as a particle, an atomized fragment of the substantive whole that is the State, from which the individual derives his dignity, his rights, and his ultimate good.

Collectivism, too, and the Totalitarianism it engenders, fails to grasp the common good, because, being subsumed under the interest of the State, there is no specifically private good to serve: "Everything within the State, nothing outside the State, nothing against the State."

If a movement away from Liberalism is to produce something other than Totalitarianism, it must take as its basis an organic view of the State, rooted in a sound metaphysics, general and special, which harmonizes the dignity of the individual with the social nature of man.