The Substance of Consciousness:
A Comprehensive Defense of Contemporary Substance Dualism

by Brandon Rickabaugh and J.P. Moreland
Wiley Blackwell, 2024, 408 pages
reviewed by T. Nelson

In this book, two theologians try to make the case for the existence of an immortal incorporeal soul using modern metaphysics. But the book also suggests a more fundamental question: is it possible in principle for philosophy ever to prove anything specific? Maybe the best we can hope for are new ideas.

The authors argue that consciousness results from substance dualism. In philosophy, a substance is something whose existence is independent of all other things and has no internal parts. ‘Substance’ by this definition is not meaningful in science as no known materials fit the requirements, and it is usually considered an abstract concept. Dualism in this case means mind vs matter.

The authors also claim that science is completely wrong about conscious­ness, and they might be correct. Heaven knows I’ve complained about that enough on these pages. Their solution, however, is to chuck science out the window. They claim that our “common­sense” intuition about consciousness, which they call “mere substance dualism” [p.14] but is really just Christian dogma, is the correct one. They define it this way:

The human person (i) is comprised of a soul (a fundamental, immaterial / spiritual substance) and a physical body, (ii) capable of existing without a body, but not without a soul, and (iii) the mental life of which is possessed and unified by the soul.

The idea of a common­sense argument is reminiscent of Aquinas, who said it was ‘obvious’ to common sense that God must exist. The authors don’t get to the Supreme Being until the end, where they speculate about whether God has a concept of redness [p.333], but they clearly hope their work will beef up religion.

Saying something is ‘obvious’ is an old trick used by math profs, but if science has proved anything at all, it is that our common­sense intuitions about the world are worse than useless. In particular, our intuitions about how the brain and our psychology work are rarely correct.

Most of the book consists of a variety of arguments in favor of substance dualism, including the ‘mereological [whole-vs-part] argument’, which says: “I endure over time as the same object. Therefore, I am not my body or brain. Since I have to be either a simple enduring soul or a body or a brain, therefore I am a simple enduring soul.” [p.145]

By ‘simple’ the authors mean that it has no constituent parts. This is the same as calling it a substance.

Another one is the ‘teleological’ argument [p.160], which the authors say ‘seems sound’:

1a If strict physicalism is true, there is no irreducible, intrinsic, rational teleology.

2a Rational deliberation exhibits irreducible, intrinsic, rational teleology.

3a There is such a thing as rational deliberation.

3b Therefore strict physicalism is false.

4a If there is irreducible, intrinsic, rational teleology, then there is an enduring, simple, rational, substantial, deliberative self.

5a Therefore, there is an enduring, simple, rational, substantial, deliberative self.

I struggle to find how either argument is coherent. How are the premises not circular? In the mereological argument, why would existing as the ‘same object’ mean you are ‘not a body or a brain’? How can anyone seriously argue, as Richard Swinburne did, from ‘being the same person as yesterday’ to ‘having an immortal soul’?

The basic terms used in this book: ‘immater­ial object’, ‘spiritual substance’, ‘unexten­ded object’, and ‘simplic­ity of the self’ needed to be nailed down and their existence proved empirically. Other­wise people would ask: If an object is immaterial or unexten­ded, then how does it really exist? If the immater­ial self is spatially unextended [p.143] doesn’t that mean there is no immaterial self?

What we have here are typical examples of the type of reasoning done in metaphysics. Hume famously ridiculed metaphysics, saying it should be “consigned to the flames.” Kerry McKenzie called it the ‘the problem of progress.’ Philosophers don’t make progress, he said, because they get bogged down in mutually exclusive all-or-nothing concepts. Then they argue over who is right and who is wrong when in fact both the concept and its opposite are inadequate to describe reality.

Philosophy isn’t unique, of course. The whole field of consciousness studies seems designed to avoid making progress. Many concepts thought to be evidence of a dualist nature (i.e., mind vs matter) are actually illusions. For instance, there is no mystery why we experience red and green differently. We associate each color with specific physical objects: calm green grass, alarming red blood, and so on. The same is true of any other emotion or sensation. Our feelings are all easily explained as memory associations and pre-programmed physiological responses to physical sensations.

The idea that the self is ‘simple’ is inconsistent with our current view of the brain as a computer. The brain, with its 86 billion parts, is as far from simple as you can get. The ‘self’ is nothing more than the brain's narrative about itself. The brain will defend this narrative at all costs, even though it is constantly changing. The human mind is more like a cacophony of different, conflicting function­alities that sometimes work in harmony and sometimes do not.

The only thing not explained in science is Chalmers’s “hard problem,” i.e. internality. Why does each human experience things from a unique perspec­tive, from “inside the information”? A person's sensations and thoughts not only possess internality but also can’t be shared with another person. This is still dualism (though not ‘substance dualism’) and it’s a mystery.

There are at least two fully developed theories in physics that might explain it if somebody were interes­ted enough to put forth the effort. But ancient Aristote­lean concepts like hylomor­phism and ‘subst­ance’ are simply too vague and indefinite to build on.

Science does not have a handle on consciousness. But the idea proposed here explains nothing: not what consciousness is, where it comes from, how it interacts with the brain, or why indeed we should believe it consists of some immaterial stuff with no known function that somehow gets poured into our heads. As a theory, it's a non-starter.

mar 15, 2026