"When Thomas Aquinas formulates his argument against contraceptive-type acts, he singles out every deliberate attempt to render a male ejaculatory act (“emission of semen”) incapable of generating. In fact, his discussion of contraceptive acts is in the context of a discussion of why intercourse be-tween non-married persons is wrong [2]. For Aquinas, this type of act is contra naturam (against nature). Aquinas’ contra naturam argument against contraceptive acts dominates Catholic theological literature on the question up until the middle of the 20th century. Since texts of canon law going back 700 years, papal encyclicals in the 20th century and the most influential theological arguments in Catholic history formulate the norm against contraceptive-type acts as universal, applied to every act by every person intended to render sexual acts sterile, the view that the Church’s condemnation only applies within marriage — and therefore does not apply to (i.e., the acts can be legitimate and even obligatory for) fornicators, adulterers and prostitutes — ought to be set aside as inconstant with Catholic traditional teaching."