As I’ve been thinking more about the issue of Church infallibility, I realized that a lot of apparent disagreements probably come down to confusion over the meaning of the term infallibility as opposed to inspiration. But in Catholic theology these terms have very distinct meanings.
Inspiration is the principle of positive guidance given to the scriptural authors to set down certain ideas, such that the result of their writing can be called the word of God.
Infallibility, though, is the principle of negative guidance given to the leadership of the Church, such that no matter how hard they try, they will never be able to definitively commit the Church to doctrinal error.
It is, of course, easy to confuse these. After all, inspiration implies that the inspired work will be protected from doctrinal error. And more than that, when catholics try to explain the idea of infallibility to protestants, we almost inevitably end up using scripture as our point of reference because it is the only example of infallibility in most Protestant theology.
Nonetheless, the two ideas are distinct. The biblical Canon, the Nicene Creed, and all the dogmatic teaching of the Church are human responses to divine revelation. But they are human responses that the Spirit prevents from going fundamentally awry.