Sedevacantism is the position of those Catholics who refuse to recognize Jorge Bergoglio as a true pope.
The sedevacantists affirm that the See of Peter is vacant, on account of the apostasy from the faith on the part of the official hierarchy, since the promulgation, in 1965, of the documents of the Second Vatican Council.
The sedevacantist reasoning is quite simple, and the facts on which it is based are empirically verifiable. More