I have been away from blogging here on Civitas Humana for a while, due to being busy with graduate work as part of my Ph.D. program. Thankfully, I passed my dissertation prospectus and advanced to Ph.D. candidacy last quarter, and so now I can dedicate more time to research and blogging.
I am going to start posting again here on Civ by beginning with a relatively short discussion of my definition of metaphysical naturalism. I have discussed some of the conceptual and ontological ways of defining both the “natural” and the “supernatural” in a couple of my previous essays on this blog (see here and here). In those essays I discuss criteria such as physicalism, reductionism, uniformity, and teleology. I think that all of these criteria are useful for articulating some of the ways that we differentiate the natural from the supernatural, but recently I have started to think that an even more minimal definition of naturalism is sufficient to deny one particular supernatural concept, namely the existence of God.
One of the major issues that I have discussed in defining naturalism is the relationship between mental states and physical states. Our brains are physical objects, but many philosophers have posed conceptual issues for how our minds (a pattern of the brain) relate to physics. Hard reductionists argue that all mental states are reducible to and identical with physical states, but there have also been proponents of supervenience, who argue that, while mental states are not directly identifiable with physical states, they still supervene upon physical states. Epiphenomenalists argue that mental states are a byproduct of physical states, but play no causal role in behavior. Discussing each of these theories can become complicated, and it often bogs down the definition of naturalism, so that it becomes difficult to use the term in ordinary discussion.
While I think it is worthwhile to explore these conceptual and ontological issues, I do not think that they are necessary to form a minimalist definition of naturalism that posits a basic relationship between mental and physical states. Rather, I will offer this more simple definition that is compatible with all of them: Metaphysical naturalism is the ontological view that all mental states are dependent upon antecedent physical states, in the sense that mental state X cannot exist, unless there is antecedent physical state Y. Notice how I have not specified whether mental states reduce to physical states or supervene upon physical states. What I have basically argued is that all minds must be dependent upon physical brains, regardless of whether they ontologically reduce to physical states in the brain or supervene upon those physical states.
This definition is useful, because it denies the existence of a number of supernatural concepts. Ghosts and souls, for example, are usually conceived of as minds that are not dependent upon physical brains, and under my definition, minds of this kind would not exist. Even physical objects inhabited by mental forces, however, would still fall under this definition. A golem, for example, is a physical object that is inhabited by a mental force. But the mental force within the golem cannot be explained by any physical state or structure within the golem itself, such as a brain. Likewise, this definition denies more abstract intentionalities that are conceived of as non-physical forces influencing the world. Karma, for example, cannot exist under this definition, unless it is defined as an ordinary cause and effect pattern within social contexts, in which reciprocal outcomes occur as a result of decisions and actions that ultimately depend on antecedent physical states.
Now, how is this useful for denying the existence of God? For the simple reason that theologians have classically defined God as lacking physical parts. The medieval theologian Thomas Aquinas (whom I have discussed previously on this blog, here), for example, argues in Summa Theologica (I, 3, ii) that God is not composed of matter and form. Likewise, God is generally understood as a conscious, aware, and even omniscient. In the words of the Shvetashvatara Upanishad (VI.2), God is “pure consciousness, omnipresent, omniscient, the creator of time.” Generally understood, even across the theologies of multiple religions, therefore, God is mental and not non-mental. But, likewise, God is not a physical being.
We could, of course, envision an omnipotent and omniscient being that was still composed of physical parts, but I have offered the theological definitions above to point out that classical theology generally denies that God is a physical being, despite his mental and conscious attributes. This relates, then, to my definition of metaphysical naturalism. Under my definition of naturalism, all mental states are dependent upon antecedent physical states, regardless of whether they reduce to or supervene upon them. Under this definition, therefore, the classical theological conception of God would not exist. My metaphysical naturalism, therefore, entails an atheistic reality.
Now, the great thing is, however, that my definition is perfectly compatible with human minds, even with all the peculiarities of our conscious existence. So long as our minds are dependent upon antecedent physical states, they are compatible with my definition of metaphysical naturalism. And what we know about the human mind, through neuroscience, demonstrates that it is, indeed, dependent upon antecedent physical states in the brain. As naturalist philosopher Richard Carrier (Sense & Goodness Without God, pp. 156-157) explains:
“The evidence seems clear: our mind, hence our very existence, depends entirely on the brain. As a mechanism, the brain must be kept healthy and active, so it can remain a system of coherent perception and thought, and we can remain ‘conscious’ and experience life itself. But stop the brain from functioning, and we can experience nothing. Our ‘consciousness’ ceases to exist.”
“The positive evidence for mind-brain physicalism also presents an almost insurmountable challenge for opponents. For example, scientists have confirmed that we only perceive things after our brains do, not the other way around. When we see a face, our brains already show activity in the area that recognizes faces a fraction of a second before we are aware of seeing a face at all. Likewise, when we make a decision, say to move our arm, we know our brain has already sent the signal to move the arm (and thus has already decided to move it) a fraction of a second before we become aware of making such a decision. This is very hard to explain unless physicalism is true. For only then would perception be a process occurring in a physical organ, one that takes time (a fraction of a second) to complete itself, and only then would self-awareness itself be such a process of perception.”
“Consider a different problem. There are many people who suffer from a condition called synesthesia, where their brain fails to physically separate sensory processing, so they ‘see’ sounds or ‘hear’ colors, and so on. If this is what happens when the brain’s wires get crossed, how can a disembodied soul experience distinct sensations? After all, the soul has no physical wires to keep such sensations separate, and clearly can’t keep them separate in synesthetes. Yet every out-of-body experience has been reported without synesthesia.”
“I could list a dozen other similar problems that opponents of mind-brain physicalism have a hard time answering, but that neurophysiologists can answer easily, often with hard evidence to back them up.”
Philosophers can still challenge in what way our consciousness relates to physical states in the brain, and whether it can truly be said to be identical with those physical states. But regardless, the evidence is clear that our consciousness depends upon antecedent physical states, so much so that we can even observe those states in the brain before we become aware of them. Humans are natural, therefore, whereas God is not.
A final point that I will raise is that we also have a very good explanation for why humans have created the concept of God, as well as other non-physical consciousnesses, such as ghosts and souls, if we live in a universe where no such minds exist that are not dependent upon antecedent physical states. The reason why is that the human mind is programed for agent over-detection. As Stewart Guthrie explains in Faces in the Clouds: A New Theory of Religion, human beings have a tendency to impute our own consciousness and agency onto non-conscious and non-mental things. Seeing the Virgin Mary’s face in a piece of toast is a simple example, but likewise, even the very concept of God involves imputing a conscious intentionality onto the origins of our universe.
As I explain in my essay “Cosmology and Time in Metaphysical Naturalism,” even if our universe had a “beginning,” in the sense that it is past finite, and even if there was a “cause” at t=0 that entailed t–>nonzero, we would still have little reason to believe that such a cause was conscious or mental. The reason why is that such a cause could have been something non-conscious and non-mental. With all of our tendencies toward agent over-detection, however, human beings have projected a conscious agency, such as God, onto the origins of our universe. But, this is a simple case of human fabrication. The current evidence that we have for every mind that exists, whether it be human or animal, is that such minds depend upon antecedent physical states, such as those in the brain. We have no evidence to the contrary. This fact, combined with our tendency to impute agency, provides a strong inference to the conclusion that God, as defined by classical theologians, probably does not exist, but is rather a human creation. In contrast, the state of the evidence for how our brains and minds work is compatible with my minimalist definition of metaphysical naturalism, spelled out above.
Admittedly, this minimalist definition of naturalism does not predict much else that is specific about our universe (such as galaxies, stars, or even biological evolution), but I am fine with that. There can be multiple possible worlds of naturalism that are conceivable, but all of them will have no mental states or minds without antecedent physical states such as brains.