The “common good” may seem a bit nebulous. After all, many in the neo-aristocracy promote a twisted version of this, namely that what’s good for the rich, is always good for the non-rich. Pope John would seem to shatter that illusion:
55. Among the essential elements of the common good one must certainly include the various characteristics distinctive of each individual people. (Cf. Pius XII’s encyclical letter Summi Pontificatus, AAS 31 (1939) 412-453) But these by no means constitute the whole of it. For the common good, since it is intimately bound up with human nature, can never exist fully and completely unless the human person is taken into account at all times. Thus, attention must be paid to the basic nature of the common good and what it is that brings it about. (Cf. Pius XI’s encyclical Mit brennender Sorge, AAS 29 (1937) 159, and his encyclical letter Divini Redemptoris, AAS 29 (1937) 65-106)
56. We must add, therefore, that it is in the nature of the common good that every single citizen has the right to share in it—although in different ways, depending on his (or her) tasks, merits and circumstances. Hence every civil authority must strive to promote the common good in the interest of all, without favoring any individual citizen or category of citizen. As Pope Leo XIII insisted: “The civil power must not be subservient to the advantage of any one individual, or of some few persons; inasmuch as it was established for the common good of all.” (Leo XIII’s encyclical letter Immortale Dei.” Acta Leonis XIII, V, 1885, p. 121)
Nevertheless, considerations of justice and equity can at times demand that those in power pay more attention to the weaker members of society, since these are at a disadvantage when it comes to defending their own rights and asserting their legitimate interests. (Cf. Leo XIII’s encyclical letter Rerum novarum, Acta Leonis XIII, XI, 1891, pp. 133-134)
The preferential option for the “weaker elements” of society: this is vital. Also a repeated theme of Pope Leo XIII. Catholics cannot escape this reality. At the very minimum, PeT 55 suggests our “attention,” a serious discernment must go into the determination of the common good of secular society.