Here is a moral fact: It is wrong to torture babies for fun. (Let T stand for “torture babies for fun.”)
But in what sense is it wrong to T? One answer, and a quite popular one, is that T’ing is wrong because it is irrational to do so. Why it is irrational can be explained a several different ways. One option is the egoist option. It is wrong to T because it is not in my self-interest to do so. It may not be in my self-interest because if I T, others might torture me back or otherwise degrade me in retaliation for my T’ing. The idea here is that it is in my self-interest to live in a world where people don’t torture each other for fun, so, in order to bring about that world, I ought to act in a way consistent with the world I want to bring about. Or perhaps we could say it is irrational to T because it is inherently degrading to myself. I destroy my own soul if I go around T’ing and that is not good for me so it is irrational for me to do so.
We might also say that it is wrong to T because it lowers the aggregate human happiness. Since living in a society where, on the whole, there is more happiness than less, I should not T because it is better to live in a more happy society than a less happy one. Or possibly it is wrong to T because there is an implicit social contract being broken when I T. By virtue of living in a society, I implicitly agree to follow certain norms and T’ing counts as a violation of those norms.
Notice that the theories I listed above all cash out the wrongness of T’ing in terms of bringing about an undesirable result. It is wrong because it will result in states of affairs that are not desirable. Surely, this cannot be the full explanation of why it is wrong to T because, presumably, it would be wrong to T regardless of the consequences. Natural law provides one way to say it is wrong to T, whether the consequences are desirable or not (and it is worth pointing out that on many of the initially suggested options, counterexamples can be constructed in which T’ing would produce desirable results and therefore our belief that it is wrong to T would be undermined).
One way to say more is to appeal to a natural law account of human rights. The idea here would be that human beings, by virtue of being human beings, have certain rights that are owed to them. T’ing would be wrong because it would be a violation of the baby’s rights that obtain by virtue of the baby being human. This is a better explanation than the ones given above because it makes the wrongness of T’ing more than instrumentally wrong.
Now, consider what naturalism might say about how it is that humans have the rights presupposed to exist on a natural law view. Remember that that naturalist is committed to the idea that everything is composed of only matter and is determined by natural laws. How could norms of action be generated from mere matter and physics? Rights and the associated norms seem like an odd fit on naturalism. Perhaps the naturalist would appeal to Kant here. Kant thought that moral duties obtain because of the dignity of human beings as rational agents. If humans are rational agents, then we ought to never treat them merely as a means and always as ends. However, Kant himself was no naturalist. And the appeal to Kant here by the naturalist is question begging because the naturalist still has not provided an account of how such properties as “dignity” obtain in a naturalistic universe.
But suppose that we grant that if humans really are rational agents, then we ought to treat them as ends and never merely as means. But consider what must be true of humans in order for them to be rational agents. Obviously, they must at least be rational and an agent. Being rational would seem to require that humans act for good reasons. Here the naturalist faces a problem because human action can be fully explained in third person, physical terms. We don’t think machines act for reasons; we think they act because of physical causes. Some naturalists, like Daniel Dennett, think that acting for reasons and being determined are not incompatible. Possibly he is right. But there is another problem. If humans are agents, this would seem to require libertarian free will. If humans are genuine agents, they must at least be understood as being the cause of their own actions (in contrast to the cause of their actions being fully explained in third-person, mechanistic ways). Again, naturalism will have trouble with explaining how humans could be agents in a naturalistic world. So Kant is no help to the naturalists here.
On the other hand, consider how such rights might obtain in a theistic universe where humans are souls resembling God. Here it seems natural to think that divine image bearers would possess essential, natural rights. If we think about Kant’s view of duty and his categorical imperative, we say that plausibly, being a rational agent just is being a divine image-bearer. And so theists can appeal to Kantian ethics as a possible way to ground the wrongness of T.
However, I suspect there is yet more to say about the wrongness of T. There is a kind of authority to the wrongness of T that cannot be fully explicated just in facts about human persons and their nature. Rather, it seems that if I were to T, I would be in violation of moral obligations that obtain not just as a result of degrading human beings. And we can see how this might be so by paying careful attention to what humans actually are, oddly enough.
Suppose of the sake of the argument that humans really are created in God’s image. This provides a ready explanation for how it is humans have rational agency and why degrading them would be wrong, for sure. However, if humans are the creation of God, then a violation of their rights is not merely a violation of their dignity as humans, but also a violation of God’s intentions for them as humans. When God created humans, he intended for them not be tortured for fun. That is built into human nature, but not reducible to it. That is to say that two kinds of violations occur: a violation against the human victim and a violation against God himself by virtue of his intentions towards humans. In this way, we actually defy God himself (by defying his intentions) in T’ing.
Now consider the gravity of these two offences taken together. When T’ing, a person not only violates another human person, but a Divine Person. A person who is ultimately valuable, completely good, holy, and maximally authoritative. That is, the breaking of moral obligations constitutes a defiance of God himself. This means that moral obligations, while serious enough understood just in natural law terms, takes on an exponentially greater seriousness when we consider that we have also violated God himself.
I think this view provides a good explanation of the phenomenology and reality of guilt. When we violate a moral obligation, the guilt we feel seems to extend beyond “feeling guilty for violating a human person.” And to be sure, that considered in itself should create a tremendous amount of guilt. But feelings of guilt often extend beyond that. We have not just harmed a person, but we have gone against the grain of Reality itself. When we do what we are morally obligated not to do, we do not just feel out of sorts with the person, but we are in contention with reality itself. Now, how could we make sense of this phenomenon? It does not seem to make sense that we have failed the universe understood naturalistically; rather the better explanation of this feeling of guilt is that we have failed a Person. That is to say, in addition to feeling guilty about violating the victim, we also feel guilty about violating the intentions of God himself and this better explains the experience of guilt.
Therefore, theism better explains how it is that humans could have natural rights and the full gravity of the wrongness of T’ing than does naturalism. And if theism more successfully explains these things, human rights and the guilt of failing a Person, it also better explains the reality of moral obligations, since both human rights and moral guilt for failing a person entail moral obligations.