In this post I'm going to explain why I'm a substance dualist rather than a hylomorphic dualist. So the title might be an instance of false advertising, insofar as I'm not really going to explain in detail why I'm not a materialist of any sort. I will say that I think there is little evidence for reductive materialism/physicalism/naturalism, and that there is strong evidence for at least some minimal form of dualism. (See, just for a couple of examples, this and this.) I won't say much more than this here, other than that I find the sort of "classic" dualist objections from qualia, intentionality, consciousness, personal identity, etc. among others convincing, and I do not feel there has been a good reply. I don't mean to sound dogmatic, it's just that, based on the evidence, at this moment I don't consider materialism to be a very strong option. If anyone is genuinely curious about this or feels otherwise though, please feel free to ask.
II. Animalist & Substance Dualist Background
Before explaining my view, I should explain the views in question. The definitions should be clear enough, but they can be made more detailed and precise.
Substance dualism I take to be the theory that the soul is a substance distinct from the body, the soul is immaterial, and that we are identical to a soul. Hylomorphic dualism I understand to be the theory that we are identical to rational animals, which are composites of matter and form, and that our soul (which is the form) has immaterial components. Animalism is the view that human persons are identical to human animals. Clearly then hylomorphic dualism is a form of animalism. Since in characteristic scholastic fashion I basically believe all material substances are hylomorphic composites, and I'm a dualist, as far as I'm concerned establishing animalism is both necessary and sufficient for establishing hylomorphic dualism. So for me the dispute really comes down to deciding between substance dualism and animalism.
In modern times, the biggest proponent of animalism is probably Eric Olson. For those uninitiated into Eric Olson's papers, the argument he gives in its favor is basically as follows:
(a) There is an animal where you are.
(b) It is thinking and you are thinking
(c) There is only one thinking thing where you are; so,
(d) You are an animal.
(a) seems impeccable. Just look at your body: It is clearly alive and in the shape of an organism, it descends from an evolutionary history, and moreover all biologists think it belongs to the species 'homo sapiens'. (b) I am a bit more unsure of; maybe you will say that thinking and rationality cannot develop out of matter, so that no organism could have thoughts. However, clearly even lower animals have some sort of conscious perceptual experience, and thus at the very least you and the animal are both having conscious awareness. You could revise (c) to say there is only one conscious thing where you are (where consciousness means having some sort of experience), and the conclusion would still follow.
Since (c) is the only premise which appears not unquestionable, the cost of denying this argument's conclusion is to say there is more than one conscious subject wherever you are. This seems counter-intuitive to say the least. First of all, all sorts of new obligations follow which we generally would deny exist; for instance, whenever you are fasting, you are subjecting the animal which follows you around to fasting and such against its will. More generally whenever you subject yourself to pain, you subject the animal to it as well. Whenever you make love to a person, not only you but another animal are as well. Etc.
I'll be honest, I have found this to be the most compelling argument in favor of some sort of animalism, which says that rather than me being identical to a soul I'm identical to an animal. (But more on this in a moment.)
However, with all that said, I find this argument quite compelling for the thesis that I am not identical to an animal:
(1) Some disembodied conscious subject psychologically continuous with me continues to exist after death.
(2) I am this subject.
(3) The animal associated with me does not continue to exist after death.
(4) So I am not identical to the animal associated with me.
(1) I take to be a datum of Christian theology (at the very least it's Catholic teaching). (2) I take to be extremely hard to deny; suppose I am about to die, and before I die I begin to say in my head "IIIIIIIIIIII think, therefore I exist". It is extremely counter-intuitive to think that if I am holding the "IIIIIIIIIIII" syllable as I die, that before my death it refers to me, then after death it either ceases to refer or refers to something other than me. In effect, denial of (2) seems to be a denial of Descartes's "cogito"; for you could be thinking, but then a moment later cease to exist--while thinking the same thought! If one doesn't like this specific example, one could probably easily come up with something similar enough to get the point across, the main point being that it is very counter-intuitive to believe that I could be thinking, and meanwhile this same conscious subject turns into a person different from me. Since (3) is equally if not more obvious than (2), from all these three premises (4) follows.
Given (4), the best way to make sense of all these facts seems to me to be substance dualism.
III. Substance Dualist Rejoinder
For a while I've sort of been at a fork in the road, not really sure which way to go; to me, both arguments have seemed very good on the face of it. However, on re-examining it, I think that Olson's argument will not appeal to substance dualists, because of his premise (b) that both the animal is thinking and you are thinking. For the animalist, the motivation behind this premise is that it seems animals can think, and thus the animal associated with you should be able to as well. However, I think the substance dualist can plausibly deny that animals think per se, if 'animal' is just taken to be the biological organism. Rather, substance dualists can plausibly say that animals have souls too; since they are also conscious, the same sorts of arguments for the immateriality of our minds would apply to theirs just as well. Hence, it is the animal's soul which thinks, properly speaking. So all Olson can really justifiedly say is that both you and an animal's soul are thinking, from which it follows you are identical to an animal's soul; but the substance dualist will have no problem agreeing that we are identical to some animal's soul.
Note what saying animals have souls does not mean: It does not entail that humans are basically just like lower animals. Human souls and lower animal souls may be very different, insofar as one possesses intellect and the other does not. It also does not entail that animals will survive death, though it may entail the possibility of their doing so. Finally, it does not entail anything really more weird than hylomorphic dualism does: For even on hylomorphic dualism it is common to say that animals (and even plants) have souls, the difference being that humans possess a rational soul including intellectual capacities, whereas lower animals have only the capacity for sensation. The substance dualist seems to me to be saying something very similar.
There is a lot more that could be said about substance dualism: How exactly does it fit into an Aristotelian metaphysical framework? What are the deeper metaphysical, epistemological, and even ethical implications? Does it fit in with Christian theology in other areas, like Christology or the Resurrection? Doesn't it just make us out to be angels? How does the soul interact with the body? What is the nature of the union between the soul and the body? While I think these are all good questions and replies can be given to all of them, I don't want to try to answer everything in this post. Answering all these questions would probably turn into a book-length project. All I want to do is explain why I've chosen substance dualism over hylomorphic dualism: While I am open to other arguments as well as hearing other options, as of now I have found the arguments in favor of substance dualism convincing, and the arguments in favor of animalism, which I take to be the key consideration, wanting.