This can all be a little confusing. Cartesian dualism and hylemorphic dualism entail a supernatural view of the mind, while property dualists may or may not be materialists. For the purposes of this series, I'm not particularly concerned with the minutiae of the different schools of dualistic thought; rather, I'm focused on the overarching thesis that the mind is fundamentally non-physical. That is, the qualia of the mind — abstractions, semantics, and metaphor — all literally exist, but exist in some non-physical capacity. Dualists get in a pickle about how exactly those qualities exist; some say it's in a separate realm or plane of existence (Platonic realism), some that they stem from the mind of God, etc. And again, those discussions aren't really relevant here — I'm only concerned with the claim that those qualities do exist independently of the body.
Dualism, though, doesn't provide an easy solution to our understanding of the mind, and that's because it comes with a host of loaded assumptions and conceptual ambiguities. In the previous post, I argued that contrary to what some dualists claim, the dilemmas faced by monism do not in principle show it to be false. And by the same token, I think it's worthwhile to point out that the dilemmas faced by dualism also do not in principle show it to be false. What's needed in a sound understanding of the mind is a model, whether dualist or monist, that successfully accounts for qualia with a minimum of assumptions, and that will be coming in the next few posts.
But yes, a minimum of assumptions. Parsimony. Something I've never liked about dualist views of the mind is that they entail a number of assumptions that appear to raise more questions than they answer. Again, this does not in itself demonstrate dualism is false. But if we can model the mind without those loaded assumptions, we'll have shown dualism to be irrelevant. So what are these loaded assumptions?
Problem 1: What is a non-physical substance?
Dualist theories of mind center greatly on claims about the mind, the self, and qualia being some variety of non-physical substances. Descartes thought that the mind and the body were distinct 'substances'; some Scholastic theologians think the mind and body are different forms of the same 'substance', one being a physical form and the other being non-physical.
We have a coherent picture of what physical things are. They have mass or energy that can be measured; they interact according to repeatable, reliable patterns we describe as physical law; and they exist spatiotemporally — that is, at a given location in space and time.
But what, exactly, is a non-physical form or substance? It is not located anywhere, nor is it composed of anything, but it is neither nothing nor nowhere. It is not governed by any known physical laws, yet it causally interacts with the physical brain and, by extension, our bodies. If a form or substance is not physical, it has no dimensions, no weight, no mass, and no energy. So what, exactly, is it? How can something even be coherently called a "form" or "substance" if it lacks the properties we generally use to describe a forms and substances in the first place? And if something does not exist at any time or in any place, in what sense does it exist at all?
The problem for dualism isn't just that these concepts seem enshrouded in semantic mystery; it's that dualists have yet to even propose a means by which semantic clarity could be ascertained. Rather, dualism seems doomed to be trapped behind a veil of metaphor. How can we possibly have a clear understanding of the mind as a non-physical entity if we cannot even have a clear understanding of what a non-physical entity is in the first place?
Problem 2: How does the mind interact with the brain?
Descartes was aware of the interaction problem, but he never developed a strong solution. On dualism, the mind causally interacts with the brain in some fashion. The type and degree of interaction varies depending on the school of dualistic thought, but the bigger hurdle is the mechanism of interaction. I'm quite fond of this quote from physicist Lisa Randall in her book Knocking on Heaven's Door, which I've referenced often and once again find relevant:
Even if science doesn’t necessarily tell us why things happen, we do know how things move and interact. If God has no physical influence, things won’t move. Even our thoughts, which ultimately rely on electrical signals moving in our brains, won’t be affected.
If such external influences are intrinsic to religion, then logic and scientific thought dictate that there must be a mechanism by which this influence is transmitted. A religious or spiritual belief that involves an invisible undetectable force that nonetheless influences human actions and behavior or that of the world itself produces a situation in which a believer has no choice but to have faith and abandon logic— or simply not care.Randall is talking about a slightly tangential issue, but the dilemma is the same for dualism. We have a clear, mechanistic picture of how the world works, and that includes the physical brain. We know that damaging specific regions of the brain can produce profound changes to one's qualitative experience. In the book Descartes' Error, neurologist Antonio Damasio discusses research in which damage to the areas of the brain responsible for emotion produce an inability to use reason, showing that our capacity to reason is deeply intertwined with our ability to think emotionally.
In a materialist paradigm of the mind, there are no non-physical elements interacting with the physical. The mind is, as Steve Novella frequently puts it, "what the brain does"; therefore, as we'd expect under such a paradigm, our capacity to think is directly affected by causal interactions in the physical brain. But on a dualist view, this is merely a lucky correlation, obscuring the real interaction between the physical and non-physical. When the brain is damaged, it's simply preventing the mind from being properly realized.
If that is true, though, there must be some mechanism of interaction between the non-physical mind and the physical brain. If the mind cannot causally affect the neurons in the brain, we will not have the capacity to think. If such an interaction exists — and it must, for dualism to be true — why can it not be modeled empirically?
Consider for a moment that in its simplest conceptualization, science is the search for stable truths. I believe science's empirical bend is incidental, not fundamental, because science simply searches for repeatable, reliable patterns in the world. It just so happens that "supernatural" or "non-physical" substances and mechanisms have not lent themselves to those types of patterns. But if dualism is true, then we ought to be able to find reliable, repeatable patterns substantiating the hypothetical interaction between the mind and brain. Even if the mind itself eludes quantitative description, dualism requires that the mind has a functional relationship with the body that we ought to be able to model empirically.
The only alternative for the dualist is to try and have it both ways: to claim that the non-physical mind causally interacts with the brain, yet produces no reliable, repeatable effect in the brain. Holding such a position requires the dualist to abandon logic and embrace magical thinking.
Toward a physical model of the mind
We've seen the dilemmas that monism faces, and we've seen that dualism raises more questions than it answers and may suffer from some intractable problems. So we have to find a new model of the mind: one that fully and coherently accounts for the existence of qualia like semantics, metaphor, and abstraction, yet does not posit any magical substances or interactions between physical and non-physical realms. Is it possible? I think it is, and it's the science of embodied cognition — a burgeoning field in modern neurocognition. A scientific understanding of the mind will necessarily overturn some longstanding assumptions about reason, logic, semantics, language, and metaphor, and those assumptions are what I'll be discussing in the next post.
Next: Old Assumptions Die Hard
Part 1: The Mind-Body Problem
Introduction: Toward an Understanding of the Mind