Within the last couple of months I have twice, in very different contexts, been presented with something like the following idea:
Suppose that someone accepts an ideology or religion that teaches or implies that some wrong act is not really wrong. Perhaps it even teaches or implies that this act is obligatory. Then he cannot be judged to have done wrong for committing the act itself but only (or even "merely") for having adopted the ideology. Since adopting an incorrect ideology is an intellectual fault and may be significantly mitigated by honest intellectual confusion, lack of information, or mistake, a person who commits a wrong--even something that would otherwise be a very grave wrong--under the influence of an ideology that teaches that it is not a wrong is significantly less culpable than a person who commits the wrong without such an ideology. We can charge him only with an intellectual error rather than with the moral wrong of the act itself.
I think this reasoning is, at least for a very significant group of cases, completely incorrect. Let's be clear: Both times that this reasoning came up, the act in question was deliberately killing an innocent person.
I am at least open to the argument that when we are talking about something on which it is understandable that the natural law should not be obvious to a person, a parallel to the above reasoning has some point to it. Suppose, for example, that we are talking about something like in vitro fertilization. I believe that in vitro fertilization is intrinsically wrong, that it is contrary to the proper valuation of a child to generate the child in a laboratory. But I understand how a person could believe that, at most, it is wrong for prudential reasons--for example, that the widespread acceptance of in vitro in society has led to many other evils, such as embryonic stem-cell research. The wrongness of conceiving a child by in vitro is, in my opinion, not glaringly obvious until you think about it for a while and have first come to see the way that natural conception is related to the meaning of the child. Hence, a married mother raised in America who undergoes in vitro fertilization--assuming that she intends to have all the embryos implanted rather than allowing any to be destroyed--and who was never taught the wrongness of the act has diminished culpability as compared to a person who, we might way, "knows better."
But it seems to me that this way of thinking becomes less and less applicable the more glaringly horrific the act in question is, until we reach a point where it is just plain wrong. When we get to exposing infants on hillsides, killing one's daughter for apostasy from Islam to Christianity, or taking one's elderly spouse off to a euthanasia clinic, I think we have crossed a line.
Suppose you don't like my examples. Then I invite you to think up examples of your own. Do you really believe that worshipers of Baal who sacrificed their infants by fire were guilty of a merely intellectual error--the error of happening (oops) to believe in the wrong god?
Imagine an ideology that taught that gang rape is permissible as a form of subjugation of the Other or as vengeance for past harm done by the woman's family group. Would that significantly alter the nature of the act and its wrongness for the men who participated in the gang rape?
My main point here is that there can be such a thing as a reductio for a worldview or religion. And if that is the case, then it must also be the case that there are some acts so glaringly, obviously wrong that any person in possession of his mental faculties can tell that they are wrong. If a person adopts a religion and then discovers that this religion holds that such an act is not wrong, or that it enjoins such an act on him, he ought to go back and rethink the religion. Blindly going ahead and committing the suicide bombing is inexcusable and, in particular, is not excusable by a prior acceptance of a suicide-bomber religion.
I think it is important to bring this up now, because I think that to some extent philosophy encourages the suppression of outrage. No matter what horrific thing someone brings up, be it infanticide, bestiality, or killing grandma, the impression one sometimes gets is that the only truly professional philosophical approach is to prescind from all horror, deliberately to suppress a horrified response, and then to ask what (other) argument one can mount--and often the only arguments the professor or interlocutor will accept are utilitarian ones--against the act in question.
This, it seems to me, cuts out without discussion the very possibility that we can know at least some ethical truths a priori and use them, then, to judge other systems of thought, which will be refuted by reductio if they lead us to condone atrocities. It also, usually, involves an unargued and underhanded imposition of utilitarianism upon young minds, which is especially pernicious.
So the fact that there is no such thing as not guilty by reason of ideology (at least when it comes to this class of glaringly obvious wrong acts) is relevant to the ethical controversies of our day. But it is also relevant to the religious conflicts, as my example of suicide bombing is meant to imply. Neither Singerism nor Islam should be treated as some sort of black box ideology which one, first, adopts in innocence and which, then, takes over one's entire ethical sense in such a way that one cannot be held responsible for acting on it. If one becomes a Singerian at the impressionable age of 18 through the pernicious influence of one's pushy ethics professor, the ethics professor may be the one most to blame at that time. But one should still be able to be shocked into sanity if one becomes a doctor later in life and has the opportunity to carry out the Groningen Protocol for oneself. If one is raised a Muslim, one's initial acceptance of Islam may be not blameworthy. But when they start telling you to strap on the bomb and go blow yourself up in the shopping mall, you have an opportunity to think again.
So let's have no nonsense about how people are just trying to do what is right according to their worldview, as if that were an excuse for heinous acts. The law is written on our hearts, and we can draw back our hands, even at the last moment, from actually committing or ordering heinous acts. Let us hope that, by the grace of God, more people in this dark world choose to do so.