Given from the Catholic Broadcasting Station 2SM Sydney Australia
Choose a topic from Vol 3:
No. A man's conscience is not always necessarily a true conscience. A man can warp his conscience. And just as he can form a wrong judgment in literature, science, economics, business, or sport, so he can form a wrong judgment as to what is correct moral conduct or evil moral conduct. A conscience is right when it is in harmony with God's law. If it is not in harmony with God's law, then it is an erroneous conscience. And we know by experience that men have often done evil under the impression that they were right. When conscience is in error, however, so that a man does wrong in good faith, we have to ask whether that man is responsible for his lack of knowledge or not. If he is responsible, because ignorant of things he ought to know and was obliged to know, he cannot be excused from sin. But if he is invincibly ignorant, having no suspicion that he is wrong, and no means of finding out that he is wrong, then he would be excused from sin even in obeying an erroneous conscience. But I have said enough to show that the individual conscience is not infallible.
The fact that your moral intuitions were opposed to those your environment should have produced is in itself an experimental proof that conscience is not a product of environment. But, even supposing that environment did dictate what good is to be done, and what evil is to be avoided, the problem would remain. For the basic thing to be explained is why men should think that good of any kind ought to be done, or evil of any kind to be avoided. Before environment can specify the operations of a human tendency, the tendency has to be there. Environment may more or less mould one's conscience. But it cannot create a conscience.