(Social justice; 04-02; p.4)

The first one relevant for catholic doctrine on society had been written by pope Leo XIII. in 1891 (cf. for the following: Pope Leo XIII.: Encyclical rerum novarum, 1891).
In it, the pope made use of older ideas - Aristotelian and explicitly of Saint Thomas Aquinas. So, the antagonism of capitalists and workers to him was artificial, not reconcilable with the idea of the human being. Besides, whereas the right to possess things was natural, this right was merely a right to use one's possessions. "Haves" thus had an obligation to use their wealth for the public good, not because of legal but of religious reasons. "Have-nots" therefore might not fight the right of possession, comprehensive expropriations could not have been justified.
According to this doctrine, the state's sphere of power was restricted, but in contrast to the mentioned protestant demands it was more than a mere liberal "night-porter". The state was also obliged to enforce the natural harmonic order and the orientation towards the public good. In the 36th section of the encyclical one finds: "[T]he principle being that the law must not undertake more, nor proceed further, than is required for the remedy of the evil or the removal of the mischief." - The guide-line of the German social market economy, "as much market as possible, as much state as needed", seemed to be outlined already there.
Besides, workers were encouraged to unite e.g. within Christian trade-unions to get their interests represented; welfare organisations independent from the churches were not rejected in general; but they were lacking "[c]harity, as a virtue, [that] pertains to the Church" (ibid. 30th section). - Leo XIII. obviously stuck to the core doctrine of the roman-catholic church that sees the institution as authoritative mediator between God and the believers.

The current pope Johannes Paul II. explicitly drew on Leo XIII. encyclical in his own from 1981, laborem exercens (cf. for the following: Pope John Paul II.: Encyclical laborem exercens, 1981).
As new element he stated that work comes before capital. So one finds in its section 12.5: "This gigantic and powerful instrument – the whole collection of means of production that in a sense are considered synonymous with 'capital' – is the result of work and bears the signs of human labo[u]r." Thus it is not appropriate according to roman-catholic doctrine to construe an antagonism between work and capital.
The "the error of economism" (ibid., section 13.3) lies in regarding especially work solely by its economical value, such seeing it merely as a factor of production. The "error of materialism" (ibid.) however lies in regarding human beings not mainly as the subject of work and making the production process possible, but as depending on production relations. Capital - as may be concluded - thus is nothing but an instrument with which work may be done. (read on here)