WHICH TRUTHS ARE CATHOLIC TRUTHS?
WHAT IS A HERESY?
Student I am moved by the words of Jerome that you brought forward to seek to know whether when blessed Jerome says, "A heresy involves a wrong doctrine", he intended to assign a definition or description of heresy.
Master Those whose opinion of the preceding question I have recorded say that taking "wrong" broadly, as any kind of pernicious or harmful thing, Jerome did not intend there to define heresy. For there are many pernicious doctrines which should not be considered heresies. If "wrong" is taken more strictly, however, as that which is pernicious in the teaching of religion, just as according to blessed Augustine [in Liber de mendacio] one kind of falsehood is that which is found in religious teaching, so it can be granted that blessed Jerome intended to assign a description of heresy there, because in this way "wrong doctrine" is taken for false doctrine contrary to orthodox faith.
William of Ockham, Dialogus,
part 1, book 2, chapters 1-17
Text and translation by John Scott.
Copyright © 1999, The British Academy