The Syllabus was divided into ten sections which condemned as false various statements about these topics:
The condemned propositions had been previously discussed and condemned in papal documents, and the interpretation of the condemned statements was intended to take place in light of the contents of those previous statements, hence the reference to other documents after each proposition. Thus the often-cited eightieth thesis is to be explained with the help of the Allocution "Jamdudum cernimus" of 18 March, 1861. In this allocution the Pope expressly distinguishes between true and false civilization, and declares that history witnesses to the fact that the Holy See has always been the protector and patron of all genuine civilization; and he affirms that, if a system designed to de-Christianize the world be called a system of progress and civilization, he can never hold out the hand of peace to such a system. According to the words of this allocution, then, it is evident that the eightieth thesis of the Syllabus does not apply to all notions of progress.
The government of France briefly tried to suppress the circulation of the encyclical and the Syllabus within its borders; it forbade priests to explain the Syllabus from the pulpit, though newspapers were allowed to discuss it from a secular point of view.
The document met with a mixed reception among Catholics; some accepted it wholeheartedly, and others were as shocked as their Protestant neighbors by the apparent broad scope of the condemnations.
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 propositions listed had been condemned as erroneous opinions in the sense and context in which they originally occurred; without the original context, the document appeared to condemn a larger range of ideas than it actually did. Thus it was asserted that no critical response to the Syllabus which did not take the cited documents and their context into account could be valid (Newman 1874). Newman writes:
The Syllabus then has no dogmatic force; it addresses us, not in its separate portions, but as a whole, and is to be received from the Pope by an act of obedience, not of faith, that obedience being shown by having recourse to the original and authoritative documents, (Allocutions and the like,) to which the Syllabus pointedly refers. Moreover, when we turn to those documents, which are authoritative, we find the Syllabus cannot even be called an echo of the Apostolic Voice; for, in matters in which wording is so important, it is not an exact transcript of the words of the Pope, in its account of the errors condemned, just as would be natural in what is an index for reference.
In the wake of the controversy following the document's release, Pius IX referred to it as "raw meat needing to be cooked." Others within the church who supported the syllabus however disagreed that there was any misinterpretation of the condemnations.
Félix Dupanloup, as bishop of Orléans, published a pamphlet in January 1865 ("La convention du 15 septembre et l'encyclique du 8 décembre" - "The September Convention and the Encyclical of December 8") in which he interpreted the Syllabus in terms of thesis and antithesis. The Church, he said, condemned general propositions stated in terms of the ideal society, not in terms of what might be prudent or just at a particular time and place. The condemnation of absolute freedom of belief, worship, speech, and the press meant that teaching false ideas could not be an ideal. It did not mean that freedom of worship, speech, and the press were not good things as practiced in particular states. It was false to say that the Catholic Church should be disestablished everywhere; but it was not true to say that it should always be established. More than 600 bishops, including the Pope, thanked Dupanloup for this explanatory pamphlet. (Hales 1954)
John Henry Newman wrote one of his last major works, the Letter to the Duke of Norfolk (Difficulties of Anglicans volume II) in response to Gladstone's attacks. In chapter 7 he explained the Syllabus along a similar line of argument as was taken by Dupanloup. Henry Edward Cardinal Manning also wrote a response to Gladstone, using the same title as Gladstone's original pamphlet.
In the United States, the Syllabus was mostly ignored. The history of Catholics in America ignoring Papal documents (such as these) which contradicted the common beliefs of the United States is known as Americanism.
Further thoughts in the same vein were expressed in Pius' encyclical of 21 November, 1873, Etsi multa ("On the Church in Italy, Germany, and Switzerland"), which is often appended to the Syllabus. There Pius condemned current liberalizing anti-clerical legislation in South America as a "a ferocious war on the Church."
Some think that the political or dogmatic propositions of the Syllabus may be abrogated by later documents coming from the Second Vatican Council in 1962. Others argue that this view results from an excessively broad interpretation of statements that had a narrower sense in their original context, and from contrasting the infallible documents of the ecumenical council with papal statements that were not infallible because they were not addressed to the whole church. For instance, proposition 77 (excerpted above) was an excerpt from an allocution relating to Spain and proposals to disestablish the Catholic church there. English historian E.E.Y. Hales argues that:
Still others argue that the points implied by the Syllabus were in fact infallible and that Vatican II in fact made no infallible statement which contradicted the older beliefs. Finally still others, the "Modernists" they would come to be called believe that dogmas can evolve, and so both the Syllabus and Vatican II taught valid things. Cardinal Ratzinger (now Pope Benedict XVI) approvingly called Vatican II a "counter-syllabus", in a gesture of frankness. See Modernism (Roman Catholicism).