… It is undeniable that a man cannot be invincibly ignorant of the
natural law, so far as its first principles are concerned, and the inferences easily drawn therefrom. This, however, according to the teaching ofSt. Thomas, is not
true of those remoter conclusions, which are deducible only by a process of laborious and sometimes intricate reasoning. Of these a
person may be invincibly ignorant. Even when the invincible ignorance is concomitant, it prevents the act which it accompanies from being regarded as
sinful. The perverse temper of
soul, which in this case is supposed, retains, of course, such malice as it had. Vincible ignorance, being in some way
voluntary, does not permit a man to escape responsibility for the
moral deformity of his deeds; he is held to be guilty and in general the more guilty in proportion as his ignorance is more
voluntary. Hence, the essential thing to
remember is that the guilt of an act performed or omitted in vincible ignorance is not to be measured by the intrinsic malice of the thing done or omitted so much as by the degree of
negligence discernible in the act.