Pius IX Issues the Syllabus of Errors Summary

  • Last updated on November 10, 2022

In his defense of a papacy under siege, Pope Pius IX proved unrelenting in his condemnation of secular ideas and values that he deemed dangerous to the spiritual mission of the Roman Catholic Church. The Syllabus of Errors, a list of such ideas and values that were to be avoided by Catholics, reflected the depth and breadth of the pope’s alienation from modern secular society.

Summary of Event

During the nineteenth century, many nationalists sought to replace the dominion of kings who ruled by divine right with constitutionally based national states united through common ties of geography, cultural traditions, and ethnic composition. Nationalists in Italy, however, faced a particularly formidable task. That land had not known unity since the collapse of the Western Roman Empire in the fifth century. By 1848, it was divided among four major powers, three of which were adamantly opposed to the trend toward national unity and democracy. Pius IX [p]Pius IX[Pius 09];and Syllabus of Errors[Syllabus of Errors] Syllabus of Errors Roman Catholic Church;Syllabus of Errors Dupanloup, Félix-Antoine-Philibert [kw]Pius IX Issues the Syllabus of Errors (Dec. 8, 1864) [kw]Issues the Syllabus of Errors, Pius IX (Dec. 8, 1864) [kw]Syllabus of Errors, Pius IX Issues the (Dec. 8, 1864) [kw]Errors, Pius IX Issues the Syllabus of (Dec. 8, 1864) Pius IX [p]Pius IX[Pius 09];and Syllabus of Errors[Syllabus of Errors] Syllabus of Errors Roman Catholic Church;Syllabus of Errors Dupanloup, Félix-Antoine-Philibert [g]Italy;Dec. 8, 1864: Pius IX Issues the Syllabus of Errors[3770] [c]Religion and theology;Dec. 8, 1864: Pius IX Issues the Syllabus of Errors[3770] Bilio, Luigi

Foremost in opposition was the papacy in Rome. By the nineteenth century, popes for nearly eleven hundred years had held title to an aggregate of territories known as the Papal States Papal States . These lands encompassed some 118,000 square miles, straddling central Italy north of Rome. By splitting the Italian peninsula into two parts, north and south, this papal domain blocked any effective Italian unification. It was therefore a prime objective of the Italian nationalist movement to strip the Papal States from the papacy. A few wanted to abolish the papacy altogether.

The pope who had to confront this grave threat to papal power was a former Italian archbishop and cardinal who took the name Pius IX upon his election in 1846. At first, liberals and democrats found much to praise in Pius IX’s progressive policies. Among other measures, he granted amnesty to more than one thousand political prisoners in the Papal States, relaxed restrictions on Jews in Rome Jews;in Rome[Rome] , and even allowed a constitution to be drawn up for the Papal States.

Militant Italian nationalists wanted more, however. They demanded that the papacy declare war on the Austrian Empire, whose troops then occupied parts of northeastern Italy, including Venice Venice;Austrian occupation of . When the pope refused, insisting that he would never attack another Christian state, riots erupted in Rome, his prime minister was assassinated, and Pius himself was forced to flee in disguise to Naples Naples . In Rome, the charismatic nationalist leader Giuseppe Mazzini Mazzini, Giuseppe proclaimed a ramshackle republic that was soon crushed by French troops, but by the time the French escorted Pius back to his city in 1850, his whole perspective had been transformed.

The pope’s bitter experience with Mazzini’s Roman republic would color the remaining twenty-eight years of his pontificate. Henceforth, Pius IX viewed with fear and loathing the modern culture of his day, above all, nationalism and secularism. In subsequent speeches and writings, the pope broadened his targets to include a wide range of modern intellectual, religious, and social currents that he regarded as potentially lethal to the Christian faith.

The papacy’s plight in Rome became desperate in 1858, when the Austrian army in northeastern Italy that had long protected the Papal States was driven from the peninsula. The victorious coalition driving out the Austrians was led by the small northern Italian state of Piedmont-Sardinia, under its able prime minister Count Cavour Cavour, Count [p]Cavour, Count;and Italian unification[Italian unification] . He had become the driving force toward the unification of all Italy.

With the Austrians gone, Cavour quickly seized the Papal States, and when the king of Naples Naples was deposed in 1861, all Italian lands but Rome were in Cavour’s hands. The same year, Cavour proclaimed the new nation and installed Victor Emmanuel II, the king of his own Piedmont-Sardinia, as the first king of Italy. Cavour became the prime minister of the new nation. Only a small garrison provided by Pius IX’s last major ally, the French emperor Napoleon III, stood between the pope and his enemies.

It was against this background that Pius IX issued one of the most controversial documents in papal history. Syllabus errorum (Syllabus of Errors) was promulgated on December 8, 1864, as an appendix to the papal encyclical Quanta cura (with what great care), but the Syllabus of Errors would take on a life of its own. Believing the time to be ripe at last, the pope had appointed a senior papal official, Luigi Bilio Bilio, Luigi , to help prepare a list of current ideas, practices, and tendencies considered heretical or otherwise inadmissible by the Church. The list was to be compiled from the pope’s own oral and written pronouncements since the beginning of his pontificate.

Pope Pius IX.

(R. S. Peale/J. A. Hill)

The resulting Syllabus of Errors was composed of eighty propositions that identified modern political, religious, and intellectual phenomena deemed unacceptable by Rome. The language of the propositions was often scathing. For example, the pope regarded nationalism, socialism, democracy, and liberalism as deplorable substitute religions in direct rivalry with Christianity. Another proposition, one clearly related to contemporary events, asserted the papacy’s absolute right to own and administer land, because such ownership was essential to the welfare and mission of the Church.

Other propositions of the Syllabus of Errors asserted that freedom of worship and of conscience could not be allowed, because true religion must tolerate no divergence. Rejected also were all forms of secular rationalism as found in modern science and philosophy, from which God was excluded. The sheer scope and harshness concentrated in this single document left many in Europe both stunned and deeply puzzled. Others were outraged. Most Roman Catholic liberals were dismayed but remained loyal. An immediate question was how binding the document was on the Roman Catholic community. Opinion on this question has never been settled by Catholic theologians. A larger question was whether the pope really intended to declare war, in effect, on the entire secular world.

In a Rome encircled by his enemies, the pope well recognized by 1864 how precarious his situation had become. He had suffered humiliation and huge losses at the hands of the new Italian state of Mazzini and Cavour. The Syllabus of Errors can be seen, in part, as a lashing out by Pius IX against his perceived tormentors. In fact, some of the Syllabus of Errors’s bitterest attacks on political and intellectual trends related directly to the actions and beliefs of the contemporary Italian government and its leading politicians, Mazzini and Cavour. The document does not explicitly limit its target to Italy, however, nor does it provide for any exceptions to its blanket condemnations.

The French bishop Félix-Antoine-Philibert Dupanloup sought in an 1865 pamphlet to soften the impact of the Syllabus of Errors by construing it as a description of a perfect society, an ideal state of affairs that could never exist in this world. Dupanloup contended that in the real world of the nineteenth century, the forms of government, science, and religion excoriated in the Syllabus of Errors had in practice to be tolerated by the Church. Indeed, some good could come from the insights of secular politics, science, and philosophy, so long as God was not excluded from them. Thus, human reason could be greatly illuminated by the teachings of the faith as in the medieval philosophy of Thomas Aquinas. Dupanloup’s rationale did not satisfy everyone, although, interestingly, Pius IX commended it as an acceptable interpretation.


The Syllabus of Errors created a sensation across Europe. Previously scattered among diverse, sometimes obscure sources, the provocative papal opinions it expressed had a far greater impact when concentrated in a single publication. Despite ambitious attempts to place the Syllabus of Errors in its contemporary context and in a less baleful light, the curious document inevitably became ready fodder for critics of the Church. In general, the Syllabus of Errors can be seen as a last defiant declaration of a venerable papal monarchy come to grief in a secular world it no longer understood. While Pius IX could not prevent the triumph of nationalism, liberalism, and science across Europe, he would not cease trying.

Worse was still to come. In 1870, Pius IX convened the Vatican Council Vatican I (1868-1870) , which approved the doctrine of papal infallibility in certain matters of faith and morals. Immediately following the council’s adjournment, Napoleon III was deposed by a victorious Prussian army. This caused a sudden evacuation of the French garrison defending Rome. The Italian nationalists swiftly seized the city and confined the pope to the tiny enclave of the Vatican. He never acknowledged the authority of the Italian state, nor would he ever leave the Vatican again.

Rome’s fall in 1870 marked the end of an era. Over a very eventful and significant pontificate, still the longest in Church history, Pius IX did keep the papacy intact, despite his loss of the papal lands. He was the last priest-king of the Roman Catholic Church. In this age of transition, the Syllabus of Errors would stand as testimony to the iron determination of a pope to prevent further erosion of the Church’s moral authority and to warn the faithful against seductive worldly attractions that could imperil their salvation.

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Chadwick, Owen. A History of the Popes, 1830-1914. New York: Oxford University Press, 1998. Contains five chapters on Pius IX, including an excellent discussion of the context and significance of the Syllabus of Errors.
  • citation-type="booksimple"

    xlink:type="simple">Coppa, Frank J. The Modern Papacy Since 1789. London: Longman, 1998. An addition to the already extensive scholarship on the Syllabus of Errors, reconsidering its place in nineteenth and twentieth century papal history.
  • citation-type="booksimple"

    xlink:type="simple">Hales, E. E. Y. Pio Nono: A Study in European Politics and Religion in the Nineteenth Century. New York: P. J. Kennedy and Sons, 1954. Sympathetic but even-handed biography of Pius IX, including the Syllabus of Errors. Still the definitive life of Pius IX in English.
  • citation-type="booksimple"


    Pope Against Modern Errors: Sixteen Papal Documents. Rockford, Ill.: Tan Books, 1999. Contains the complete text of the encyclical letter Quanta cura, including the Syllabus of Errors.

Strauss Publishes The Life of Jesus Critically Examined

Italian Revolution of 1848

Pius IX Decrees the Immaculate Conception Dogma

Italy Is Proclaimed a Kingdom

Vatican I Decrees Papal Infallibility Dogma

Bismarck Introduces Social Security Programs in Germany

Papal Encyclical on Labor

Related Articles in <i>Great Lives from History: The Nineteenth Century, 1801-1900</i>

Count Cavour; Giuseppe Mazzini; Napoleon III; Pius IX. Pius IX [p]Pius IX[Pius 09];and Syllabus of Errors[Syllabus of Errors] Syllabus of Errors Roman Catholic Church;Syllabus of Errors Dupanloup, Félix-Antoine-Philibert

Categories: History Content