“Hey, heads up, guys. Here comes Substance Dualism”
If contemporary philosophy were a high school and theories were students, Substance Dualism would be the kid who has a reputation for bad breath, horrible fashion sense, a shady family history, and for saying gauche and tactless things on a regular basis. The cool kids wouldn’t be caught dead talking to him, and others would avoid him assiduously. If any were unfortunate enough to come in contact with him, they’d dismiss him with a patronizing smile. “See that kid over there? That’s S.D. He’s mostly harmless, but, man, he has some crazy ideas. Everyone knows who he is, but no one pays him much regard.”
In the cafeteria of Philosophy High School, Substance Dualism eats alone.
Substance dualism, for those who aren’t familiar, is the view that humans are composed of two distinct substances—an immaterial mind (or soul) and a physical body. This view, or something like it, is the “common sense” belief held by the vast majority of people, both throughout history and across the world today. But, as anyone who’s taken an introductory course in the philosophy of mind knows, substance dualism is, as Jaegwon Kim puts it, “not a live option” for most contemporary philosophers. The majority view is materialism, alternatively known as physicalism, which holds that humans are composed solely of matter, and that the mind is either strictly physical or strictly supervenient (dependent) on the physical brain. We are, in the words of Marvin Minsky, “computers made of meat.”
Thankfully, philosophy is not a high school, and theories are not judged by popularity contests…or, at least, they shouldn’t be. Substance dualism’s unpopularity is irrelevant to whether it is true or false. Our concern should be with the reasons to accept or reject it, and we should do our best to eschew argumentum ad (un)populam.
So, what are the reasons that most contemporary philosophers reject substance dualism in favour of materialism? Surely there are very strong reasons against it (beyond its horrible fashion sense)?
As I see it, there are three main reasons philosophers reject substance dualism: First, discoveries in neuroscience have ostensibly removed the need to posit an immaterial mind. Brain researchers have established links between what we think, dream, and experience, and the immensely complex whir of processing in our brain. Our mental activity appears to be strictly correlated with neuronal activity.
Second, dualism is a more metaphysically complex theory than materialism. Ockham’s razor dictates that we choose the metaphysically simpler theory (materialism) over the more complex (dualism), provided the simpler theory explains the phenomena in question equally well.
Lastly—and this is the whopper—the interaction between the mind and brain is seemingly inexplicable if the mind is not physical. How does the immaterial mind interact with the physical brain? If the mind has no mass, charge, or extension in space, how can it cause neurons in the brain to fire? And how could neurons in the brain cause changes in the immaterial mind? This last consideration, known as the “interaction problem,” is the most cited reason for rejecting substance dualism.
In a series of three posts, I will evaluate each of these three main objections in turn. I will argue that they are, all things considered, not the decisive reasons to reject substance dualism that so many take them to be—especially in comparison with the problems facing materialism.
So, what do you think? Is this a fair list of the major objections against substance dualism? Are there other objections that I should address?
A Philosopher's Take 
Travis R
February 2, 2015
I have a potential #4, though it may fall under the interaction problem. What is the origin of the mind under substance dualism? That is, how do we get from sperm + egg to mind, or on an evolutionary timescale, from last universal common ancestor to animals with minds?
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Gordon Hawkes
February 3, 2015
Thanks for the comment, Travis. The objection you suggest is certainly a problem for substance dualism. But how should we classify it? First, we can make a distinction between constitutive questions (What does the mind consist of? What is the ontology of consciousness or rationality?) and origin questions (When did mind emerge in the history of the universe? How did it arise?). Every theory of mind—materialist, dualist, or idealist—faces both types of questions. The objection you suggest could be interpreted as either.
When answering origin questions (“How or when did the mind emerge in our evolutionary history?”), many philosophers make the assumption of naturalism—the metaphysical view that there exists the natural order, consisting of fundamental stuff (for most, this means physical stuff) governed by fundamental laws…and that’s it. Nothing else. There’s nothing outside Nature. It should be clear that, if we assume naturalism is true, no amount of rearranging or recombining the original fundamental stuff will yield a new fundamental substance that is both distinct from the rest of Nature, and in some way causally independent of the natural (i.e., physical) order.
So, if taken as a challenge to explain the origin of substantial minds, I would classify it as an objection from naturalism. Naturalism, however, cannot merely be assumed (since, by definition, it excludes the possibility of substance dualism). The objection only carries weight insofar as naturalists provide independent arguments for naturalism, and show it to be superior to its alternatives. (I might address this as a fourth objection.)
If we interpret the objection as a constitutive challenge, then I think you’re right to classify as a form of the third objection (one might reasonably ask: “How do the causal powers of sperm + egg either yield an immaterial mind, or cause the body to come into causal relationship with an immaterial mind?”). That said, your comment has made me realize that I was rather sloppy in my characterization of the third major objection. Strictly speaking, the so-called interaction problem is a specific problem within the more general category of objections from mental causation. (Objections from causal closure or the completeness of physics, and the so-called pairing problem, would fit under this heading.)
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Travis R
February 3, 2015
Gordon,
I’m not sure if I was able to accurately extract a request for clarification from your response, but I think there was one there so I’ll give it a shot. The intent of the question was to view it from the assumption that substance dualism is true. In other words, given the presence of immaterial minds linked to physical bodies, how do we account for the fact that what appears to be a purely physical sperm + egg combination eventually comes to join with, or generate, an immaterial mind? Then, on an evolutionary scale, the question is how did evolution occur such that what appears to have been purely physical simple replicating systems evolved into animals that became joined with, or generated, immaterial minds? Where do we find the cause for the joining or generative function?
As an extension to this question I’ll note that the most prolific answers to these seem to invoke theism or panpsychism. Theism of course opens up a massive suite of new questions and panpsychism essentially suggests that mind was actually there all along as a guiding force behind the formation of these more complex manifestations of mind-bearing creatures. In other words, it wasn’t actually true that sperm + egg or LUCA was purely physical – mind was there in some hidden way. That then seems to present a chicken and egg problem, however, since the content of our minds seems to be dependent on both experience and the high-order complexity of the brain, yet mind as the guiding force from simple to complex infers that it already knows that complexity is the end goal and it is working toward that end.
I think that last paragraph may not have come out as clear as I would have liked so you’re welcome to ignore anything that doesn’t make sense. In the end, I’ll just say that I’m interested in seeing the follow-up posts and hope that I have in some way helped refine your argumentation.
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Gordon Hawkes
February 5, 2015
Hi, Travis. You raise some very good questions. These are questions that substance dualists debate amongst themselves. Please excuse me if I come across as somewhat pedantic in my response. (It sounds as if you might be somewhat familiar with the debate already.) I’m working through these things myself, so it’ll be helpful for me to lay them out as clearly as I can.
You raise the question, “Assuming substance dualism is true, how does the union of sperm and egg, which appears to be a wholly physical event, cause (or generate) an immaterial mind (or soul), or cause the organism (the zygote) to become attached to, united with, an immaterial mind (or soul)?” Substance dualists disagree among themselves as to the potential answers, but the answer they give will at least partially depend on the form of substance dualism they subscribe to.
There are three main forms of substance dualism:
1. Cartesian Dualism: On this view, mind is a substance that has the ultimate capacities for consciousness (i.e., sensation, thought, belief, desire, and volition). The mind is connected to the body through a causal relation—that is, my body is mine because I can cause things to happen to it.
2. Thomistic Dualism: On this view, humans possess a soul, and the soul is broader than the mind. Not only does it include the capacities for consciousness, it is also responsible for the unity, growth, animation, and form of the physical entity that comes from the joining of the egg and sperm. What makes the physical entity human is the soul, which is “diffused” throughout the physical structure. Without the soul, the body would cease to be human, strictly speaking. After death, the body, while still possibly composed of many living cells (a dead body can still have many live cells) ceases to function as a coordinated whole, and instead becomes merely a group of cells, since it was the soul that directed the unified function of the body.
Your point about how “it wasn’t actually true that sperm + egg or LUCA was purely physical” is spot on according to the Thomistic view.
3. Emergent Dualism: A spatially extended, immaterial self emerges from the functioning of the brain and, after emerging, is able to exert its own causal powers. (See William Hasker, The Emergent Self for a defense of this view).
Now to your question: “How does the physical entity “join with, or generate, an immaterial mind”?
There are three answers that go way, way back to the ancients, although they viewed the matter in terms of how the soul joined the body or was generated: (1) traducianism, (2) creationism, and (3) platonic pre-existence.
1. Traducianism: The soul, like the body, is derived from the parents, according to metaphysical laws. (Metaphysical Law 421: “If a spermatozoan should come into union with an ovum, a soul shall at that moment come into existence and be united thereafter with the physical entity.”) This view strikes me as parallel, or very similar, to the view of (naturalistic) property dualists like David Chalmers. Given the right physical conditions, consciousness emerges or comes into existence. While it would fit with all three versions of substance dualism, emergent dualism seems to require something like traducianism. Of all the options, something like traducianism seems to me the option that would fit best with a non-theistic metaphysics. Emergent dualism, in fact, as I understand it, is the result of philosophers who think the evidence of mind requires dualism, yet who want to ensure that it is compatible with the grand evolutionary story of our origins…unlike the next option.
2. Creationism: God creates each soul especially for each body. Well, it’s pretty obvious this option necessarily requires theism.
3. Platonic pre-existence: Immortal and pre-existing souls temporarily unite with the body. This view would fit with something like a Buddhist metaphysics, since it clearly allows for reincarnation. However, it was put forward by classical theists, as well. Augustine, for instance, believed that God drew from a well of pre-existing souls and joined them with bodies.
I don’t think traducianism and Platonic pre-existence are necessarily united to a theistic or pantheistic worldview, but they are, I think, necessarily united to a MENTALISTIC worldview (a metaphysics that makes mind fundamental to the universe, e.g., panspsychism [as you mentioned]). Any such theory faces problems that physicalism avoids, but physicalism faces its own problem: How does mindless matter turn into mind? How does reason emerge in a non-rational, blind universe?
As you can see, we can still ask the question, “But how EXACTLY does the union of the soul with body work?” I’ll end with what I consider an especially important reminder in contemporary philosophy: All explanation comes to an end somewhere. If we had to explain every explanation with a further explanation, then we would find ourselves in a vicious regress. If I have good evidence THAT our minds our immaterial, I don’t also need to be able to explain HOW they work. Put another way, we can offer an answer to the constitutive question without having an answer to the origin question. That’s precisely what many physicists do who have no metaphysical answer as to how the physical universe came into being, and I think we can proceed the same way in the philosophy of mind.
My concern over the next three posts will not be to argue in favour of substance dualism. Rather, my goal is simply to show that the major arguments offered against substance dualism are not good reasons for rejecting it. There might be broader concerns, which you’ve touched on, that might lead one to reject substance dualism.
P.S. I didn’t quite understand the chicken and egg problem you mentioned. I agree that the content of our minds (our mental properties) depend on the brain and on experience, but I didn’t understand what you meant by the “mind as the guiding force from simple to complex”.
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Travis R
February 5, 2015
Gordon,
Thanks for the elaboration on your understanding of the origin question for substance dualism. The “chicken and egg” comment was admittedly awkward and poorly worded so I would like to try and offer a formalized clarification:
P1) Intention requires the mental properties of intelligence and purpose
P2) Intelligence and purpose only manifest with a complex physical arrangement (e.g., neural network)
P3) Intelligence and purpose are only functional after training through experience over time
C1) By P1, P2 and P3, intention only manifests with a combination of a complex physical arrangement and experience
P4) All known complex physical arrangements in C1 developed from less complex physical arrangements which did NOT manifest intelligence and purpose
P5) The manifestation of the mental was intentional
C2) By C1 and P4, there was time with no manifestation of intention. This, by P5, implies that the mental did not manifest.
This isn’t so much meant to be a logical argument for a the conclusion of C2 – clearly the mental actually has manifest – but rather a way to tease out the errant assumptions through the examination of the objections, such as:
Obj1) P1 is false. To this I ask whether we can really call it “intention” if it doesn’t involve knowledgeable planning toward a goal.
Obj2) P2 and P3 are false. This would accord with theism or any system wherein a causal force knows in advance how to bring about our more familiar, physically correlated mental manifestations.
Obj3) P4 is false. This is either a denial of evolutionary origins or an assignment of intelligence and purpose to the simplest organisms.
Obj4) P5 is false. This carries two implications, either (a) the evolutionary result of increasingly frequent and capable mental manifestations is just a coincidental by-product of a purely physical process, or (b) the mental is not different from the physical and so was an active participant in the physical process.
I’m not asking anybody to engage with this. Mostly I just wanted to see if I could make sense of what I was trying to say in the original comment.
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Gordon Hawkes
February 5, 2015
Hi Travis. This is much more clear! Thanks for taking the time to clarify. “Reading maketh a full man; conference a ready man; and writing an exact man.” – Francis Bacon
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keithnoback
February 3, 2015
I’d hope you would state what might constitute(?) a separate substance. A description of pure mentality (mind distinct from content/’physical’ reference) should do. Is there an epistemology available for that discussion?
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Gordon Hawkes
February 5, 2015
Hey keithnoback. I must thank you for asking one of those seemingly simple questions that gets an amateur philosopher like myself in a mental tangle. Excuse me while I jump down a certain rabbit hole…
The classic definition of ‘substance’ is something that HAS properties, but is not HAD by anything else. E. J. Lowe, in his Introduction to Philosophy of Mind, defines a substance as “any sort of persisting OBJECT or THING which is capable of undergoing changes in its properties over time.” Or here’s James Madden in Mind, Matter, and Nature: “A substance HAS properties, or properties EXIST IN substances, but a substance (in this sense) is never had by, nor exists in, anything else. Substances are not ways of being, but entities that exist in certain ways. Will (who IS TALL) and the water (that IS COLD) are substances. Philosophers argue about which things are substances, what ultimate kinds of substances there are, and even whether there are any substances at all…”
As to “what…constitutes a separate substance”—in the present context, I initially interpreted you to be asking more specifically, “How can we distinguish between physical and non-physical substances?” Well, if you already buy into the metaphysical category of substances, then, in order to answer the question, you’d need to define “physical” and “non-physical” first. I take that distinction to be one that everyone makes, but that few, if any, can precisely define. I’d say any substance that has certain properties—mass, charge, etc. (there are certain properties that almost all would agree are quintessentially physical)—would count as a physical substance.
Understood that way, we could differentiate physical substances from non-physical substance by their properties. But here I run into a problem: The more I reflect on what is meant by “substance,” the less it seems appropriate to classify any substance qua substance as physical. The metaphysical category of substance, as defined above, already seems to go beyond what fits with physicalism. For instance, on the classical view, an acorn is a substance, and the oak tree that grows up from that acorn is one and the same substance. That individual substance, then, could not be the physical parts of the acorn or the oak tree since the substance persists or survives the physical changes. If we assume physicalism is true, and that only physical substances, properties, and events exist, then what would we mean when we say that the brain is a physical “substance”? If we allow that its identity as a substance persists through physical change, doesn’t that, like the acorn, make the substance something beyond the physical stuff?
Substance dualists would argue that understanding your self to be a substance fits with your common sense understanding. For instance, when you introspect, you presumably (although I don’t know you well enough to say for sure) will believe that the person who is reading this response is the same person who wrote the original question. The ‘you’ is a substance, they’d say, that persists through changes in its properties.
Now, in regard to what sort of epistemology is involved, I’ll have to think some more on that, but my initial thought is: We reflect on ourselves, our experience of being a self, of being a conscious mind. We can infer much, I think, from our experience. It is our experience of being selves that persist over time, our experience of the different modes of consciousness (viz. sensations, thoughts, beliefs, desires, and volitions) that ground the dualist’s inference that we are not just our bodies. Are those immediate experiences somehow less grounded, less justified, than, say, the inferences we make in science? I take a key insight of Descartes’ to be that whatever third-person, scientific inferences (judgments about the external world) we make, those inferences are made through our first-person, internal perspective. If we cast doubt on our first-person perspective understanding of ourselves on the basis of claims about the external world, it seems to me we are in danger of cutting off the branch we are sitting on. At the very least, we need to take our first-person experience seriously.
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keithnoback
February 6, 2015
Well put. Just as problems arise in distinguishing ‘physical’ and ‘non-physical’ substances, problems arise in claiming solid identities, even for ourselves. I don’t believe that the person reading the response is the same, in a rigid sense, as the one writing the question. Damned close, but not the same.
The problem I see arising from this imprecision is that the imprecision seems to flow from the dependency relation inherent in causality. Even talking about substance to substance causation would appear to allow reduction to a standard, monist story.
Anyway, thanks for the reply, and as a fellow amateur, I look forward to your further thoughts on the topic that makes me a geek.
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Joe
February 3, 2015
I will be happy to read your responses to the first 3 objections.
I think Travis asks you to address different issue then the third. The third objection as I understand it is how can an nonmaterial thing interact with a material thing?
But on a related note how is it these minds come into contact with interactable bodies? Like he said do they grow out of the body and not exist before? Do they preexist and randomly strike into a body like lightening might strike a house?
I how things came to exist is also a question we can’t entirely answer for material things either.
I don’t think it is necessary to answer these questions as the fact that we don’t know how it works is not a true objection. But I would be interested in your thoughts.
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Gordon Hawkes
February 5, 2015
“I don’t think it is necessary to answer these questions as the fact that we don’t know how it works is not a true objection.”
I think this is spot on. One of the most helpful distinctions I have come across is the distinction between knowing THAT something is the case and knowing HOW it is the case.
But, that said, I think that questions like Travis’s are still very important, especially as the challenge the internal consistency of a theory.
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Gordon Hawkes
February 5, 2015
P.S. See my response to Travis above for more.
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angramainyu2014
February 5, 2015
Hi Gordon,
I would suggest a modification of the first one, which you describe as “discoveries in neuroscience have ostensibly removed the need to posit an immaterial mind”.
That seems to assume a need to posit that without the discoveries in question. While I would count discoveries as evidence against dualism, I wouldn’t be inclined to say there was such a need.
But additionally, regardless of whether there was such need, I think discoveries in neuroscience plus many other facts provide evidence against substance dualism (i.e., they make it less probable).
For example, if we had found that altering the brain (with drugs, or a blow to the head) affected our ability to move our body, but not our intentions, goals, etc., then that would have been at least some evidence for dualism.
More generally, if scientists had found that some aspect of our mental experiences, properties, etc. – say, our values, goals, memories, feelings for others, anything – were impervious to anything we do to the brain, that would had provided some strong evidence for dualism – in other words, based on that, we should have increased the probability that we attribute to dualism.
But science has found not a single case of that, and moreover, when studying different ways in which the brain is altered, damaged, etc., they kept finding more and more mental experiences, properties, etc., that can be so affected.
For example, brain damage, drugs, etc., can alter what a person wants, values, fears, etc., her memories, her capacity for math, language, etc.
I guess it’s debatable how good the evidence is (perhaps you’re planning to challenge that it’s good), but it is evidence against dualism, so one ought to reduce the probability one assigns to dualism after learning those facts.
Other than that, there are plenty of objections but I’m not sure they classify as major ones – still, perhaps a lot of small objections in the end weigh more than a major one.
But for example, how about objections that target not dualism in general, but specific forms of dualism but which can be combined with other objections of that sort to make a more general case.
For example, on Thomistic dualism, the soul makes the physical structure human, and is responsible for the form. But that implies separate kinds of entities with different souls. Evolution counts against it. One may consider the human souls of present-day people, then the previous generation (also human), etc. Eventually – on Thomism – one would reach a non-human.
But those human children born to nonhuman parents still had a brain similar to those of their parents (like the rest of the body), looked like their parents, learned their culture from their parents and other nonhumans (i.e., how to hunt different animal, how to obtain food different sources, how to make different tools), and also learned rules of behavior from their parents and from other nonhumans, either because they were taught or by observing the adults.
So, the first humans would have believed themselves to be the same sort of being as their nonhuman parents, would have learned toolmaking, hunting strategies, rules of behavior, etc., from nonhumans, and generally they would have been much more similar to their parents than to any present-day human. But then, how is it that the soul makes the body human? After all, it seems the soul was not very relevant. The body was (and in particular, the genes), since the human agents in question were much more like their nonhuman parents than they are to present-day humans. There seems to be no good reason, based on looks, behavior, etc., to place those people in the same category as we are placed, rather than in the same category as their parents.
Granted, someone might claim that there was some sort of evolutionary jump, getting a vastly different brain from one generation to the next, or very different behavior with pretty much the same brain, etc. But such claims would be (at least; I’d say a lot more than that) unwarranted, so that would make Thomistic dualism at least unwarranted. There are more objections, but in the end, I think this kind of argument provides
One can raise more arguments of this sort against Thomistic dualism by considering genetic engineering – actual or potential but clearly possible even if unethical -, etc.
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Gordon Hawkes
February 8, 2015
Hi angramainyu2014. Your comment is a perfect segue into my next post (a response to the objection from psychophysical regularities between mind and brain). I’ll respond more in that post, but I’ll add a few other comments here.
For dualists, the perceived need to posit an immaterial mind is based on the need to explain the salient features of our mind. In other words, the EXPLANANDUM (the thing that needs explaining) is the set of mental capacities that appear, in principle, to be inexplicable in physical terms (e.g., rationality, a priori knowledge, intentionality, consciousness [qualia], the unity of conscious experience, the experience of being a self, self-identity over time, the experience of apparent free choice, etc.) and the EXPLANANS (the explanation of that phenomenon) is the immaterial mind.
Many physicalists acknowledge that these salient features of mind do, in fact, create a “temptation” to dualism. But, for those same physicalists, positing an immaterial mind as an explanation for our mental capacities is, as Daniel Dennett would say, tantamount to “giving up.” Even though (arguably) they have no satisfactory explanations for the features of mind mentioned, they are holding out for an eventual answer, made possible by the inevitable advance of physical science. (Many dualists argue that there are good reasons to believe that, even in principle, no such physical answer can be provided.)
You argue that evolution would count against Thomistic dualism. Perhaps…but I wanted to make several points in defense. First, in your comment, you seem to assume the Darwinian, gradualist picture of evolution on one hand, but then, on the other hand, create a stark division between “the first humans” and “their parents.” I don’t think your description, which was meant to illustrate a problem for Thomistic dualism, fits with the Darwinian picture. Because the progress of neo-Darwinian evolution is infinitesimally gradual, there wouldn’t be a sharp dividing line between an individual that we could call the first HOMO SAPIENS and its immediate predecessors.
That said, I do acknowledge that the physical change in the course of evolution is much easier to conceive than an “evolution,” so to speak, of immaterial souls. How would that work? Wouldn’t the souls have to be changing (evolving) with (or even prior to) the corresponding changes in each subsequent generation of physical bodies along the evolutionary chain? What forces or causes would be propelling that change in the immaterial souls? You definitely highlight a genuine problem for the Thomistic dualist.
Yet, many Thomists insist upon a union of evolutionary theory and Thomistic dualism. Also, for Thomists, the “soul” (or “form”—roughly Aristotle’s “formal cause”) is what makes any living thing the particular living, unified, animated organism it is and not just a hunk of non-living matter. Aristotle and Aquinas thought ALL living things have a soul (e.g., vegetative, animal, rational). Odd as it may sound, I think many Thomists would argue that they have an advantage over materialism in explaining both the origin of life and the progress of evolution—because Thomistic dualism allows for TELEOLOGY (the evolution of the universe is progressing toward an end), whereas materialism does not. In fact, this is (very) roughly the critique of naturalist Thomas Nagel against neo-Darwinian materialism, that is, that teleology is needed to make sense of the universe.
[Please note that I’m not advocating Thomistic dualism, but simply offering tentative responses on its behalf. Also, I’ve been somewhat fast and loose with my use of “Thomist”—not all Thomistic dualists are also Thomists, followers of the philosophy of Thomas Aquinas.]
Lastly, evolutionary theory, as it is understood by many, already ASSUMES materialism—both before and after the existence of life. If “evolution” is understood to be a purely physical process in a purely physical universe (wouldn’t you say that’s the very picture we have in our minds when we conceive or imagine evolution?), then an appeal to evolution as evidence against dualism subtly begs the question, as I see it. It ends up being just an appeal to materialism.
I appreciate your comment. Please let me know if I’ve misunderstood you in my response.
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angramainyu2014
February 8, 2015
Gordon, thanks for the reply.
On the issue of whether there is a need to posit an immaterial mind, I have to say I’m not sure the term ‘material’ (or for that matter, ‘physical’) is precise enough to do the philosophical work it’s supposed to be doing in the context of material/non-material debates. But that aside, I don’t see why substance dualism would explain things any more than property dualism – which would also handle rationality, etc.
On evolution and Thomism, it seems there’s been a misunderstanding:
Actually, I accept the gradualist picture (even punctuated equilibrium is gradual in this context) when it comes to the changes in mental capacity, looks, etc., but I do not create a stark division between “the first humans” and “their parents”. On the contrary, I argue that Thomism creates the start division in question, and that’s where the problems begin – given, precisely, a combination between gradualism and Thomistic dualism.
Agreed for the most part, but that’s exactly the point I’m trying to make. Thomistic dualism does not fit. The problem is the combination of gradual changes with the start division resulting from the different kinds in which Thomistic dualism categorizes substances.
For example, on Thomism, humans would be ‘rational animals’. But there is no such thing as a half-rational animal: either the soul is that of a rational animal, or it is not. Combining that with common descent, there are humans born to non-humans, and the children would be the same kind as we are, unlike the parents. Adding gradual changes, surely those children would be far more similar to their parents than to us, in all of the ways I described in my previous post and more (including their minds).
The Thomist seems committed to weird radical evolutionary leaps.
Granted, many Thomists do claim that Thomism is compatible with evolution. What I’m arguing is that it’s not compatible with the picture of evolution that we get from present-day science. In fact, even being agnostic with regard to gradualism would not be enough for the Thomist, who is committed to evolutionary leaps.
It gets even worse when we consider the evidence of the correlations between changes in the brain and changes in the mind. What about the first humans?
If the Thomist claims that their brains are very much like the brains of their parents but their behavior is more like ours – rational animals -, then there would be a vast behavioral change with almost no change in the brain, which is extremely improbable given our observations.
If the Thomist claims that there was a radical change in the brains too making them vastly more intelligent, capable of reason, etc., from one generation to the next, then how would that ever happen without genetic engineering or something like that (sure, they may claim that, but why should anyone believe it?)?
One may add more arguments by considering hypothetical genetic engineering: what if someone (say, some aliens) were to start with humans, and gradually (by means of genetic engineering) turn them into far more intelligent beings? Or beings with very different values? And it doesn’t have to be only humans. Any gradual genetic changes are a problem, at least if the end result is a big change.
Granted, a Thomistic dualist might not be a Thomist, and perhaps might separate the categories differently, but that does not seem to resolve the general problems raised by gradualism – at best, they might move the problem from one point in time to another one. I guess a Thomist dualist might try to reply by adding zillions of different kinds of souls (to account for gradual changes), but I think that that would create other, equally serious problems.
On the issue of materialism, as I mentioned I have doubts about the adequacy of the terms, but in any case, my arguments against Thomistic dualism in this context are compatible with – for example – emergent dualism, or panpsychism, so there is no assumption of materialism.
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Gordon Hawkes
February 10, 2015
Hi angramainyu,
Well done. This is a much more clear presentation of your arguments. I take the following passage to be a concise summary of your argument:
“The problem is the combination of gradual changes with the start division resulting from the different kinds in which Thomistic dualism categorizes substances. For example, on Thomism, humans would be ‘rational animals’. But there is no such thing as a half-rational animal: either the soul is that of a rational animal, or it is not. Combining that with common descent, there are humans born to non-humans, and the children would be the same kind as we are, unlike the parents. Adding gradual changes, surely those children would be far more similar to their parents than to us, in all of the ways I described in my previous post and more (including their minds). The Thomist seems committed to weird radical evolutionary leaps.”
You’ve given what I would consider a very good critique of a marriage between (naturalistic) evolutionary theory and Thomistic dualism. I think your argument forces the Thomistic dualist to choose between two options: (1) abandon Thomistic dualism, or (2) appeal to special creation in the case of the origin of the rational soul.
A Thomistic dualism that maintains that rational souls are distinct IN KIND from other sorts of souls is, as you have clearly explained, incompatible with blind, unguided, naturalistic Darwinian evolution.
In the interest of playing devil’s advocate, here’s a possible reply that a Thomistic dualist might offer:
The materialist faces a parallel problem: Just as the Thomistic dualist must explain the appearance of rational souls from non-rational souls (i.e., the evolutionary leap that you rightly point out), the materialist must explain the appearance of rational minds from non-rational matter. How did that jump happen?
I think your critique is right on the money. But, if your critique is forceful, then I think we must allow that a parallel critique of materialism on the same front (the jump from non-rational to rational) is, at least to some extent, also forceful. (This isn’t even to mention the leap from unconscious matter to conscious minds—a leap that seems as strange and inexplicable as the leap from animal soul to rational soul.)
Thanks again for your helpful comment. It’s a really helpful and clear critique of Thomistic dualism. Inspired by your comment and others above, I might add a fourth post to respond to the critique of substance dualism from evolutionary theory.
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angramainyu2014
February 10, 2015
Gordon, thanks for the interesting reply, and you’re welcome.
I’d like to add a couple of thoughts in reply to some of your points. Specifically:
Agreed, but (2) on its own would require something like an interventionist creator. While most Thomist dualists are Christians, an Aristotelian hylomorphist (or someone with a similar view) would seem to be in trouble just because of that.
Also, as I see it, a commitment to theism would, on its own, be enough to make Thomistic dualism too improbable.
But for those who disagree, I would like to raise another issue:
By positing special creation, the T. dualist may offer an explanation as to how rational animals come from, but that does not remove the problem of the commitment to very improbable statements. In other words, the T. dualist would still face the following options:
1. There was a radical change in mental properties from non-rational animals (the parents) to the first rational animals, but the brain and DNA was almost the same.
2. There was pretty much the same behavior, so the first rational animals were mentally much more similar to their non-rational parents, than to us.
3. There was a radical change in the brain also.
Option 1. is very improbable given observations of correlations between brain and mind.
Additionally, there is an independent reason to deem it very improbable: our observations of other primates, and in particular, bonobos and chimps. They are tool makers and rule-enforcers, they have culture and so on. Given the gradual change in brain size from our last common ancestor with them to present-day, gradual changes in behavior appear far more likely than a jump.
Overall, I deem it extremely improbable.
Option 3. faces the same problem from observation of behavior as option one, and in addition to that, those brain changes seem to require massive DNA change – i.e., God doing genetic engineering, or just creating Adam and Eve separately -: I also reckon it’s extremely improbable.
Even the disjunction of 1. or 2. seems extremely improbable, in my assessment.
Option 2. seems lethal for T. dualism, since one may ask: “What role does the rational soul play, given that different entities have pretty much the same mental properties when they have pretty much the same brain regardless of whether they have a rational soul?”
However, the T. dualist is not only committed to rejecting my assessment that the disjunction (1. or 2) is extremely improbable, but she seems committed – at least if she accepts at least enough modern science to reject YEC and things like that – to asserting that (1. or 2.) is true or almost certainly true. But that’s unwarranted.
So, I think if the argument above does not show that T. dualism is false, at least it shows it’s unwarranted to believe it’s true, after reflection.
Side note: There are a number of other arguments I’d raise against T. dualism (considering scenarios involving genetic engineering, advanced aliens from other planets, strong AI, etc.), but that would make this post too long.
As I see it, the problem for the T. Dualist is not so much having to explain the appearance of rational souls, but rather, a commitment to the claim that the jump happened (i.e., to something like the disjunction of 1. and 2. above) – which I think is very improbable, but otherwise it’s at least unwarranted.
As for the materialist, I’m not sure what materialism is, but briefly, my take on this is that – as we can see from chimps, orangutans, bonobos, several corvids, etc. -, the ability to reason is not exclusive to humans, and also comes in degrees (indeed, observation of humans of different ages and/or with different mental conditions also shows that the ability to reason comes in degrees).
An anti-materialist might press the issue, and ask – say -: “But hos did the first jump happen, from not rational at all to minimally rational?”
As I see it, there is a difficulty with the question, namely that it assumes that the term ‘rational’ is precise enough to make that distinction. I think that – just as it happens with at least the vast majority of our colloquial terms -, that is probably not so, and at least one is not warranted to assume that it is so – i.e., that the term ‘rational’ is precise enough for that.
However, I think the materialist doesn’t need to be committed to that. She might say something along the lines of: “Change in mental properties, capacities, etc., was gradual, as was change in other respects. Whether the term ‘rational’ is precise enough to distinguish some mentally very similar entities between rational and non-rational is a semantic issue I take no stance on, but my stance is that change was gradual”.
That said, if this objection is a problem for materialism, or even if materialism less probable than T. dualism due to some other objection (perhaps, one based on the conscious/unconscious distinction), I would still say that T. dualism is very improbable – and at least unwarranted.
On that note, imv if T. dualism were the most probable of the many options (both dualist and monist) philosophers have so far considered (perhaps, due to even stronger objections to each of the other options), it would still be very improbable, and too improbable to warrant belief, after reflection.
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Gordon Hawkes
February 13, 2015
Hi angramainyu2014,
Thanks again for your thoughtful, clear comments.
This might seem like a small point, but I think we should be careful, in this context, about rejecting a theory on the basis of probability. The context: an argument from neo-Darwinian evolution against Thomistic dualism, and, by extension, in some cases, theism.
Darwinian evolution, by any account, is extremely improbable—yet scientists and philosophers don’t see that as a reason to reject the theory. I think it might be better to frame the discussion in terms of which theory is the BEST EXPLANATION. Of course, what list of factors determine the “best explanation” is up for debate (probability would likely be on many thinkers’ lists), but probability alone, considered in isolation, cannot be the deciding factor in this case, since Darwinian evolution itself is mathematically improbable to the extreme, yet that is not a hindrance to its wide acceptance.
You list three options open to the Thomistic dualist. I think the most promising is Option 1: “There was a radical change in mental properties from non-rational animals (the parents) to the first rational animals, but the brain and DNA was almost the same.” Option 2 makes the rational soul irrelevant. Option 3 breaks significantly with the Darwinian picture, and we’ve been considering how a Thomistic dualist might marry Darwinian evolution with T. dualism.
And yet I agree that Option 1 is a problem for the T. dualist. The creatures that immediately preceded the rational homo sapiens in the evolutionary chain would be almost indistinguishable physically from us, yet they would lack all mental capacities that the rational soul is responsible for (see bottom). You’d have a situation where nothing would physically prevent mating between the two groups, although the former might be less than appealing to the latter (“SWF, looking for a sensitive, intelligent partner who enjoys discussing cave paintings. No animal souls need apply. Third cave from the oak tree.”) What would the offspring of a rational soul and animal soul parents end up being?
But… there still seems to be a parallel problem for the physicalist/materialist. (Let’s ignore rationality for the moment.) Of all our mental features, phenomenal consciousness most clearly creates a problem for the hope of physical explanation on a gradualist picture of our development, since consciousness seems to be an ON/OFF type of mental feature. How would adding more physical parts, or arranging the physical parts differently, suddenly give us consciousness (however rudimentary)? The physical changes would be minute at each step of evolutionary development, but the change from unconscious to conscious seems like it would be immediate, not gradual.
I’d love to see inside other philosophers’ minds to see how they deliberate over difficult questions. I picture the ideal as being something like a ledger with pros listed on one side, cons listed on the other, and then a relative weight assigned to each reason. If you have a theory with no good reasons on the pro side, and lots of good reasons on the bad side, then you give it up. But it’s our responsibility to actually survey the reasons fairly on both sides of the ledger. So, in the debate between substance dualism and its rivals, the question is which ledger has the most strong reasons on the pro side and the least on the con side. As you mention at the end of your comment, though, it might be reasonable to withhold assent to a theory, even if its ledger is comparatively the best. (The theory might only have very weak reasons on the pro side, and very strong reasons on the con side.)
You make a good point regarding the jump from a non-rational to a rational mind: whether or not one considers this a problem is going to depend on one’s definition of “rational.” But that, my friend, is a great topic for another blog post! (Or dissertation.)
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angramainyu2014
February 13, 2015
Gordon,
Thanks for your thoughtful reply as well.
This might a case of miscommunication, but I’m talking about probability after factoring in the observations, not prior probability.
If I reckoned that evolutionary theory is improbable, then I wouldn’t believe it’s true (I’m not sure whether that’s tautological; perhaps, it’s not since a person can have contradictory beliefs, impossible beliefs, etc.), and if that’s not tautological, I shouldn’t believe it is true.
However, after reflection and in light of present-day observations, I reckon evolutionary theory (the basic core, not every detail) is extremely probable, even if it’s incomplete and there are some things to figure out.
On the other hand, I don’t think that having a theory that is the best explanation available (of a certain fact) justifies believing it’s true. It may well be that the best explanation available is improbable – it’s just that any alternatives are even more improbable -, in which case one ought not to believe any specific one is true (though maybe we agree on this? You said “it might be reasonable to withhold assent to a theory, even if its ledger is comparatively the best”. I’m saying that sometimes one ought not to believe that the best available theory is true)
For example, suppose that we have the following options:
a. Panpsychism.
b. Substance monism + Property Dualism.
c. Thomistic Dualism.
d. Property Reductionism.
e. Cartesian Dualism.
f. Emergent Dualism.
g. Neutral Monism.
h. Disjunction of all other alternatives considered by philosophers so far.
i. So far, no philosopher has considered the right one.
If, after reflection and counting observations, P(i)>.05 (for example; I’m not saying we can properly assign specific numbers, though), but P(c) > P(j) for any j other than c or i, then Thomistic Dualism is the best explanation available, but one should not believe it’s true.
Similarly, if each option has probability less than, say, 1/6, one should not believe that any specific one is true (even though the disjunction of them all is true).
Granted, the Thomistic Dualist might disagree with my probabilistic assessment, and so my disagreement with them would endure – as I would actually expect, given that disagreement on these matters tends to be very persistent.
That aside, I agree that option 1. is the best for the T. dualist among those three (though I think changing her mind and no longer being a T. dualist is better), but I think it’s a bad option, for the reasons I’ve been given.
As for the offspring of a rational animal and a non-rational one, my take on this is that given that there were already rational animals born to non-rational parents (on T. dualism), it seems that what kind of soul the offspring gets does not depend only on what the parents are, but partly or entirely on what the soul maker decides (the T. dualist already seems committed to the existence of a powerful being guiding evolution at least when it comes to making some souls, for the reasons I gave in my previous post), so I don’t think this adds another problem for the T. dualist that wasn’t already there – but I still think it’s a big problem.
With regard to the parallel problem for the physicalist/materialist that you mention, I think that’s a problem unless there are states such that there is no fact of the matter as to whether the entities are conscious (maybe the term “conscious” is actually not precise enough).
However, assuming there are no such states, I think it’s smaller problem (i.e., not nearly as big as the problem for the T. dualist), because the beginning of subjective experience on physicalism may happen at an early stage, before biological evolution, and jumps at that stage are not problematic.
For example, having mass or not having mass is also an on/off feature, but that’s not a problem for theories that objects with mass began at some point. Generally, some jumps (given quantum theory) are not so improbable. Rather, a problem for the T. dualism is where the jump would happen on T. dualism. The T. dualist may take no stance on when exactly it happened, but it’s still at some point when evolution had been going on for a very long time already, complex brains already existed, etc.
In the particular case of option 1. (but 3. is worse, and 2. as you say makes the rational soul irrelevant), there would be radical differences in behavior and cognitive capacity with pretty much the same brains. Observations from neuroscience count against that.
That aside, let’s the reply (from the physicalist) I suggested above does not work, and the problem you raise is at least as serious for the physicalist as the problem I raise is for the T. dualist. If that is so, then I would say physicalism is very improbable too (by the way, I don’t have the belief that any specific one of the alternatives under consideration is true).
On the other hand, panpsychism has no difficulty with any of that. Neither does neutral monism (though there might be other factors that count strongly against each of those).
In re: definition of “rational”, I think that the definition is up to the T. dualist (it’s their theory, after all), so they have options within some range, but I think as long as the T. dualist is committed to some big jump (ala 1. or 3.), the problem remains – and I don’t see how they can avoid such jumps without losing much of their metaphysics. Maybe a radically changed sort of T.-like dualism could avoid them; I’d have to see it to assess it.
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