Syllabus of Errors

[1] It collected a total of 80 propositions that the Pope considered to be current errors or heresies, pairing the briefest headings with references to the various documents where the actual teachings are found.

The documents referenced by the Syllabus were intended to be a rebuttal of liberalism, modernism, moral relativism, secularization, and the political emancipation of Europe from the tradition of Catholic monarchies[2] but some relate to specific nations.

A cover letter by Cardinal Antonelli notes that Pope Pius IX had ordered the creation of the list, in case some Bishops had not read all his recent allocutions, speeches or encyclicals.

In 1874, the British Leader of the Opposition William Gladstone published a tract entitled The Vatican Decrees in their bearing on Civil Allegiance: A Political Expostulation, in which he said that after the Syllabus no one can now become [Rome's] convert without renouncing his moral and mental freedom, and placing his civil loyalty and duty at the mercy of another.Catholic apologists such as Félix Dupanloup and John Henry Newman said that the Syllabus was widely misinterpreted by readers who did not have access to, or did not bother to check, the original documents of which it was a summary.

The Pope particularly condemned the recent rise of Spanish-style liberalism and anti-clericalism in South America, which shares the same tradition of hostility to granting religious toleration and allowing Classical Christian education rooted in the Trivium with mainstream Republicanism in France, for unleashing "a ferocious war on the Church".