The possibility that the received Catholic teaching on the morality of contraception has been proposed infallibly by the ordinary magisterium was generally ignored in the debate which took place after the publication of Humanae vitae. Everyone agreed that Paul VI proposed no ex cath edra definition, and the supposition that Pius XI might have proposed such a definition in Casti connubii was hardly mentioned in the debate. Thus those who dissented from the teaching reaffirmed in Humanae vitae and those who defended the legitimacy of such dissent proceeded directly from the nondefinitive character of Paul VIs pronouncement to the possibility of licit dissent from noninfallible teachings, ignoring the possibility that the nondefinitive pronouncement contained a reaffirmation of a teaching which, even if never defined, was already infallibly proposed by the ordinary magisterium. Those who supported the teaching reaffirmed in Humanae vitae and who questioned the legitimacy of dissent from it similarly argued that the teaching should be accepted as authoritative and binding, even if noninfallible. As evidence of the obligatory character of the teaching, they frequently cited Vatican II, Lumen gentium 25, regarding the religious allegiance of will and of intellect due authentic teaching of the bishops and especially of the pope even when the infallible exercise of the magisterium is not in question. – from “Contraception and the Infallibility of the Ordinary Magisterium” (Theological Studies, Vol. 39, No. 2, June 1978)