Here at the end of Chapter Four, Francis concludes his discussion of integral ecology by examining two important topics: (1) the common good, which is either entirely absent from discussions or woefully distorted, and (2) the notion of inter-generational justice, so important for thinking about long-term goods which we bestow on our children and grandchildren. (In the course of these passages you'll see that Francis invokes the two great guiding principles of Catholic social thought: solidarity, active concern for the good of society and all of its individual members, and subsidiarity, the notion that needs are best understood and satisfied by people who are closest to them.)
IV. THE PRINCIPLE OF THE COMMON GOOD
156. An integral ecology is inseparable from the notion of the common good, a central and unifying principle of social ethics. The common good is “the sum of those conditions of social life which allow social groups and their individual members relatively thorough and ready access to their own fulfilment”.
157. Underlying the principle of the common good is respect for the human person as such, endowed with basic and inalienable rights ordered to his or her integral development. It has also to do with the overall welfare of society and the development of a variety of intermediate groups, applying the principle of subsidiarity. Outstanding among those groups is the family, as the basic cell of society. Finally, the common good calls for social peace, the stability and security provided by a certain order which cannot be achieved without particular concern for distributive justice; whenever this is violated, violence always ensues. Society as a whole, and the state in particular, are obliged to defend and promote the common good.
158. In the present condition of global society, where injustices abound and growing numbers of people are deprived of basic human rights and considered expendable, the principle of the common good immediately becomes, logically and inevitably, a summons to solidarity and a preferential option for the poorest of our brothers and sisters. This option entails recognizing the implications of the universal destination of the world’s goods, but, as I mentioned in the Apostolic Exhortation Evangelii Gaudium, it demands before all else an appreciation of the immense dignity of the poor in the light of our deepest convictions as believers….
V. JUSTICE BETWEEN THE GENERATIONS
159. The notion of the common good also extends to future generations…. Once we start to think about the kind of world we are leaving to future generations, we look at things differently; we realize that the world is a gift which we have freely received and must share with others. Since the world has been given to us, we can no longer view reality in a purely utilitarian way, in which efficiency and productivity are entirely geared to our individual benefit…. The Portuguese bishops have called upon us to acknowledge this obligation of justice: “The environment is part of a logic of receptivity. It is on loan to each generation, which must then hand it on to the next”.….
160. …When we ask ourselves what kind of world we want to leave behind, we think in the first place of its general direction, its meaning and its values. Unless we struggle with these deeper issues, I do not believe that our concern for ecology will produce significant results. But if these issues are courageously faced, we are led inexorably to ask other pointed questions: What is the purpose of our life in this world? Why are we here?... It is no longer enough, then, simply to state that we should be concerned for future generations. We need to see that what is at stake is our own dignity. Leaving an inhabitable planet to future generations… is [an issue] which dramatically affects us, for it has to do with the ultimate meaning of our earthly sojourn.
161. Doomsday predictions can no longer be met with irony or disdain…. The pace of consumption, waste and environmental change has so stretched the planet’s capacity that our contemporary lifestyle, unsustainable as it is, can only precipitate catastrophes…. We need to reflect on our accountability before those who will have to endure the dire consequences.
162. Our difficulty in taking up this challenge seriously has much to do with an ethical and cultural decline which has accompanied the deterioration of the environment. Men and women of our postmodern world run the risk of rampant individualism, and many problems of society are connected with today’s self-centred culture of instant gratification. We see this in the crisis of family and social ties and the difficulties of recognizing the other. Parents can be prone to impulsive and wasteful consumption, which then affects their children who find it increasingly difficult to acquire a home of their own and build a family. Furthermore, our inability to think seriously about future generations is linked to our inability to broaden the scope of our present interests and to give consideration to those who remain excluded from development. Let us not only keep the poor of the future in mind, but also today’s poor, whose life on this earth is brief and who cannot keep on waiting….
 SECOND VATICAN ECUMENICAL COUNCIL, Pastoral Constitution on the Church in the Modern World Gaudium et Spes, 26.
 Cf. Nos. 186-201.
 PORTUGUESE BISHOPS’ CONFERENCE, Pastoral Letter Responsabilidade Solidária pelo Bem Comum (15 September 2003), 20.