>>588721
Because the "adapting to the modern world" part has a very narrow meaning in the Syllabus, which doesn't appear in the documents of Vatican II.
It's obviously incorrect, if not outright heretical, to say that the Church cannot adapt to the times; it's easy to see why both by logic and by history. All the things Church does are but means to the end, which is glory and goodness of God and salvation of souls; and means must always by their nature be subject to the end. Several of these were commanded by God (e.g. that the Eucharist is to be celebrated - "Do this in rememberance of Me") and as such we, trusting Him who gave them, can and must obediently continue doing these things, and can never discard them.
However, the particular way these things are done, in addition to many other actions and laws of the Church, are mere human, fallible inventions, and can be changed by relevant, human authority (e.g. an ecumenical council); because in the end they are just means, and less effective means should be replaced by more effective means. For example, if a particular way of evangelisation doesn't work, then we shouldn't continue evangelising this way; rather, we should use a more effective way because one or another method of evangelisation is just a fallible, created, human tradition whose value lies in how well it attains its end.
We see this kind of adaptation to circumstances of time countless times in Church history: Counter-Reformation comes to mind as perhaps one of the most prominent - the society and culture had changed, and the Church as it functioned before had been inefficient when faced with the new and previously unknown danger of Protestantism; and so, the Church adapted to the times - this is the essence of aggiornamento as expressed by the modern popes; efficient church, not modernised doctrine.
In addition, it's equally obvious that the Church can take what is good and true even from an evil source; and if modern civilisation treats some issue rightly, the Church can adopt this, not because of the particular civilisation which invented or developed this approach, but because the approach is good, useful and agrees with the doctrine. As the saying goes, even a broken clock is right twice a day: and when we know it's right, it's illogical to refuse to accept what it says only because it's a broken clock.
As for the quote from Syllabus, the New Catholic Encyclopedia says:
>The publication raised a furor that had been long expected. The Italian and French governments allowed the press to publish and comment upon it, but denied the ecclesiastical authorities equal freedom in explaining the propositions; and so misconceptions about the condemned errors became widespread, especially since many of the errors had specific reference to the Italian situation. For example, condemned proposition 80 reads: "The Roman pontiff can and should reconcile and harmonize himself with progress, with liberalism, and with recent civilization." This condemnation was drawn from the allocution Jamdudum cernimus (March 18, 1861), which had reference to the Piedmontese government's idea of progress and civilization, i.e., closing of religious houses, enforcement of secular education, secularism, and anticlericalism. Other nations had different views on progress, liberalism, and civilization, and misinterpreted the meaning of the pope; Catholics became confused about some of these condemnations, although many were very clear, e.g., those with reference to the denial of Christ's divinity and to atheism.
It's a quote from another document and explicitly presented as such, rather than an independent statement, in the Syllabus and should be interpreted not on its own, but in light of that document, which concerns a very specific situation.