The author assumes that it is worthwhile to approach Catholic Social Teaching from a philosophical standpoint. He analyses whether and how in the selected passages the term "responsibility (towards future generations)" is presented as relational and in at least three parts (Chapter 1). He deals with the issue of differentiation of the term "future generations" and with the problem of the rights of future persons (Chapter 2). Finally, the author reflects upon the two main theses of concept of intergenerational justice from the encyclical Laudato si’ while investigating the meaning of the ultimate instance of responsibility and sanctions, using the mental experiment inspired by the encyclical (Chapter 3). The author concludes that in Catholic Social Teaching the notion of "moral responsibility (towards future generations)" is usually implicitly presented as at least in threeparts, but not always and not clearly. He suggests a basic differentiation of the term "future generations" and defends the thesis that we can be currently bound by the rights of future persons although these do not exist yet. According to the author, the mental experiment leads to theological insights into the meaning of the ultimate instance of responsibility and of personal immortality, namely already when we assume the philosophically plausible precondition of the possibility of sanctions.