Starting in the 19th century, popes began to use their encyclicals to address hot-button social issues of their time. Each pope addressed a different issue, but built upon the legacy that the previous pontiffs created.
On May 15, 1891, Leo XIII wrote Rerum Novarum, deploring the inhumane working conditions of the working class.
Pius XI, 40 years later on May 15, 1931, reiterated the principal points of his predecessor in his encyclical entitled Quadragesimo Anno. He continued to develop the Church’s stance in regards to workers as well as commenting on the social order.
Mater et Magistra
On May 15, 1961, St. John XXIII wrote Mater et Magistra on social progress. He built upon his predecessors work and continued to dwell upon the rights of individuals and their relationship with the state.
Pacem in Terris
On April 11, 1963, St. John XXIII wrote Pacem in Terris, which further explored the rights of individuals in society.
St. Paul VI wrote Populorum Progressio on March 26, 1967, to comment on the “development of peoples.” He again built upon the foundation of prior encyclicals and reiterated the Church’s response to society’s pressing issues.
St. John Paul II wrote Laborem Exercenson September 14, 1981 to reinforce the Church’s teaching about workers’ rights and solidarity. It was to be published on May 15, but was delayed due to the assassination attempt on his life on May 13, 1981.
On May 1, 1991, St. John Paul II wrote, Centesimus Annus to further cement the principles in Rerum Novarum and to apply it to the current time.
Caritas in Veritate
Pope Benedict XVI released Caritas in Veritate on June 29, 2009, focusing on the concept of charity and how it should effect every corner of society.
In the beginning of his pontificate, Pope Francis wrote Laudato Si’ on May 24, 2015 to address the many social problems caused by poor stewardship of creation.
Pope Francis wrote his encyclical, Fratelli Tutti, on October 3, 2020, and sought to apply the many principles of his predecessors to the current world, which at the time was in the midst of a pandemic.