Syllabus of Errors

(A Syllabus Containing the Principal Errors of Our Time), published by Pius IX on Dec. 8, 1864, in an appendix to the encyclical Quanta cura.

The 80-paragraph Syllabus of Errors enumerated the “principal errors and false doctrines” condemned in encyclicals, epistles, and other documents issued by Pius IX since he assumed the papacy. It condemned progressive scientific and social thought, freedom of conscience, separation of church and state, rationalism, democracy, socialism, and communism—any thinking that contradicted the interests and doctrine of the church, its claims to a superior role in society and the state, and the papacy’s claims to secular authority. The concluding paragraph condemned liberal Catholicism’s thesis that the “Roman pontiff can and should reconcile and harmonize himself with progress, with liberalism, and with modern civilization.” The resolutions of the First Vatican Council (1870) included the basic tenets of the Syllabus of Errors.

The decree Lamentabili, published in 1907 under Pius X, included a new, 65-paragraph Syllabus of Errors condemning modernist ideas in Catholicism.