A good freind of mine asked me how a Pope can be infallable and things such as the Inquisition can happen. He also said (and of this I’m not sure about) that The Church has apologized for some of the things it has done i.e. the inquisition. And if the Church takes back decisions it has made, how can those decisions be infallable? How might I respond to his question???
Your friend suffers from a common misunderstanding. Papal infallibility is not a guarantee that Popes will not make mistakes or even that they will not sin. It is simply a gift of the Holy Spirit whereby Popes cannot err when proclaiming doctrine on matters of faith and morals.
For more on the subject see Papal Infallibility: catholic.com/library/Papal_Infallibility.asp