I've been looking at the case of the moral status of animals in my summer ethics class, and I've just finished rereading a piece by Tom Regan, who argues that animals have full moral rights and thus shouldn't be treated as means to human ends, including any use in laboratory experiments, for food, as pets, or for entertainment. His is just one of several views I'm looking at, and it's not new to me, since I've taught this article or another similar one several times in the past. So I wasn't expecting to notice an argument that I didn't remember from any of the previous times I included his work, but there's an argument about souls that strikes me now as particularly bad in a way that it surprises me not to have noticed it before.
He considers and dismisses several reasons people might have for thinking humans have rights that other animals do not have, and one in the list is the view that humans have immortal souls, and animals do not. His argument against this method of distinguishing the moral status of humans and animals was simply that the issue of whether humans have immoral souls is controversial, and we shouldn't base our stance on one controversial issue on our stance on one that's even more controversial.
I can't say I'm impressed by this argument. Most people who believe in immortal souls do not do so based on the controversial arguments offered by philosophers, most notably those of Plato and Descartes. There problems with their arguments. Someone who holds an alternative view has some pretty easy dodges. They can deny a premise or point out that certain inferences don't follow if materialism is true. Of course, the derision held for mind-body dualism among professional philosophers is reserved for few views, and philosophers who find these arguments unconvincing are usually unwilling to recognize that pretty much every philosophical argument for any position that doesn't command near-universal agreement is just like that. I'm not at all sure that Plato and Descartes' arguments are as bad as they're made out to be, so I'm not willing to grant that immortal souls are more controversial than views on animal rights, as Regan seems to think.
But there's a deeper reason why this argument can't easily succeed. If we do have immortal souls, then that might make a big difference in how we think about moral status. Suppose it does. Suppose also that there's no convincing argument either way. Does it follow that we shouldn't assume that we have immortal souls that animals lack? Suppose it does. I think it's only fair to say that we also shouldn't assume that we don't have such souls. Regan's claim that there's no good reason to think we have moral status that animals lack would then turn out to be true, but it would also be true that Regan has no good reason to think we don't have moral status that animals lack. We should hold no view either way, and he thinks he can just assume one stance on this issue that he thinks is more controversial than the question he's primarily writing about. He's done the same thing he's claiming the believer in immortal souls shouldn't do.
There is one reason you might favor one side, though. Regan could argue that he would assume one way rather than the other on this question because he's giving the benefit of the doubt to those who, if we ignore their possible rights, we do great wrong to. If we assume animal rights, we prevent what might be a serious wrong to animals. I should say that those who use this reason better not be pro-choice in the abortion issue on the ground that we don't know for sure if a fetus has moral status (and there are indeed people who take such a view, including the current President of the Unites States).
But there are at least two considerations that would at least moderate such a presumption. One is that the human benefit of various ways we treat animals, not least being the significant scientific advances from animal experimentation that produce benefits both for humans (and probably animals), means we would be doing a great wrong to humans (and possibly for animals) if it turned out that animals have no rights but we pretend they do.
But we also need to take into account the fact that a large number of people who believe in immortal souls do not do so because of philosophical arguments but because their religious beliefs include that view. To evaluate whether such people's beliefs are rational we'd have to evaluate the entire question of the rationality of religious belief, something I've certainly spent a lot of time on in other places but won't get into here. That's yet another controversial question, but if it turns out religious belief can be rational then there might well be a rational reason for thinking we do in fact have immortal souls that animals lack. Without knowing that, Regan's argument now has to rely on two unestablished conclusions and thus is doubly question-begging even if he's right that the other side's argument is question-begging.
I happen to think I've got good reasons for thinking my belief in immortal souls and in the non-existence of immortal souls in animals, even before I've considered the question of the moral status of animals. I don't think animals have no moral status, but I don't think Regan can dismiss a view held by the majority of the world's populace as easily as this, since he hasn't actually even given any arguments against the two views he'd need to resist for his argument to go through (although maybe he does do that elsewhere, but I doubt it since he does say that he hopes he does have an immortal soul, and he does speak once of God as if he believes in a divine being). I don't think the status of animals is anywhere near as simply as humans having full moral status because of immortal souls and animals have none because of no souls, but surely more needs to be said to refute that kind of consideration than simply noting that it's controversial.