Comparing the social encyclicals by popes in the first century after the publication of Rerum Novarum, one can notice an evolution not only in their attitude toward the real political-economic situation but also in their postulated social solutions. It seems that an analysis of the contents of the encyclicals gives one the right to propose the statement that the general view of politicaleconomic life is rather similar and quite comparable to the model of democratic capitalism in the first encyclicals. However, the later period witnessed gradual but consistent change of this stance. At first, the encyclicals published in this period barely perceptibly remove themselves from, and then act with obvious distance toward the social solutions of democratic capitalism. This tendency is brought to a halt and partly turned around in the first two social encyclicals of John Paul II.
Maciej Zieba, "From Leo XIII's Rerum Novarum to John Paul II's Centesimus Annus," Journal of Markets & Morality 5, no. 1 (Spring 2002): 159-166