The Syllabus now ranks as my #1 Papal Encyclical of all time. First, you gotta dig the title. It just rolls over your tongue and lingers at the tip, poised for ironic re-purposing. I tried to think of some equally genius equivalent, like The Compendium of Blunders. Not bad, but not ironic. And it would take too long to write.

Pius IX: best known for his work on Virgin Birth.
Pope Pius IX wrote the Syllabus in 1864 to denounce the popular heresies of the day as his papal predecessors had done before him, except that Pius IX faced a new devil conjured by science and a burgeoning capitalist class. Previously, the term “heresies” referred the beliefs of competing religious sects, most recently Protestantism, but by Pius IX’s reign that dispute had largely settled itself. The Syllabus addresses a new form of impiety that we would call Modernity, identified by Pius IX as the “Scourge of Liberalism” in the subtitle. From here on out, the Church accepted a truce in overtly religious wars in order to arm itself against rationalism, philosophy, democracy and even more radical political ideologies like communism.
Pius IX found a mere 80 “errors” in the Modern world, actually far fewer than I find. He listed the offenses as expressed by their proponents, rather than turning them into condemnations. Consequently, the Syllabus reads like a bullet-point presentation of contemporary thought and political ideals:
- Human reason, without any reference whatsoever to God, is the sole arbiter of truth and falsehood, and of good and evil; it is law to itself, and suffices, by its natural force, to secure the welfare of men and of nations. (Error #3}
- Philosophy is to be treated without taking any account of supernatural revelation. (Error #14)
- The State, as being the origin and source of all rights, is endowed with a certain right not circumscribed by any limits. (Error #39)
- The Church ought to be separated from the State, and the State from the Church. (Error #55)
- No other forces are to be recognized except those which reside in matter, and all the rectitude and excellence of morality ought to be placed in the accumulation and increase of riches by every possible means, and the gratification of pleasure. (Error #58)
- It is lawful to refuse obedience to legitimate princes, and even to rebel against them. (Error #63)
- The Roman Pontiff can, and ought to, reconcile himself, and come to terms with progress, liberalism and modern civilization. (Error #80)
That last one had to sting!
Of course, heresy has political causes and consequences in a system where the Church has rights to taxation, land ownership, corporal punishment, tribunals, etc. From the late-18th century on, countries all over the world took those rights from the Church and royals and placed them in the hands of civil governments exclusively. Anti-colonial revolutions succeeded throughout Central and South America, and in Mexico. Rulers met at the Congress of Vienna in 1815 to withdraw the map of Europe (literally) in order to stop the spread of liberalism and nationalism, only to be washed away by a wave of revolutions in 1848 (the same year Marx and Engels published The Communist Manifesto). Additionally, the Holy Roman Empire officially dissolved in 1804 after centuries of slow disintegration and nearly disappeared by the time Pius IX wrote the Syllabus.
Anyone who wants to vie with me for nerd points, check out The Syllabus of Errors for yourself.