Mind-Matter Problem

The Mind-Matter Problem, which involves attempts to address theories of the mind, can be divided into three major approaches (or more broadly, into two):

• a) Reductive Physicalism: This stance considers the mind equivalent to bodily activity (i.e., a physical entity). Cognitive neuroscience, which views mental states as nothing more than chemical reactions among neurons in the brain, is a representative example of this perspective.
• b) Epiphenomenalism: This stance regards the mind as a byproduct of bodily activity. If mental states closely interact with the brain, then the mind may be viewed as a kind of byproduct generated by the brain.
• c) Emergentism: This stance is a dualist approach that entirely challenges (a) and (b). Emergentism posits that the mind is a separate entity, distinct from the physical entity, and that a mind can “emerge” when a physical entity becomes sufficiently complex. Attempts to explain brain phenomena as emergent properties of large clusters or systems using statistical field theory or chaos theory are representative examples.

In fact, (a) is merely an “extremely strong (radical)” version of (b). Imagine a ball (representing the brain) rolling on a road—according to (b), the shadow of the ball represents the mind, whereas (a) considers the ball itself to be the mind. The shadow of the ball has no causal effect on the movement of the ball on the road. Thus, one might consider the concept of the mind—at least as a physical phenomenon that is presumably reducible—completely irrelevant, focusing solely on material phenomena. Consequently, from the perspective of (a) and (b), the term mind refers to a phenomenon dependent on the physical world, and any soul independent of the physical world would be unequivocally irrelevant. Naturally, mental causation is also not a crucial factor for proponents of these stances, as mental elements in mental causation are considered equivalent to physical elements. This kind of thinking is, in essence, the core of (b), which encompasses functionalism, connectionism, computational theories of mind (CTM), identity theory, anomalous monism, and many other concepts. Philosophers of psychology generally dislike this stance, and rightly so. Logical humanists are bound to be discontented with it. After all, the extension of (b) aligns with a view that dismisses all systems of human civilization and human existence itself as meaningless. If human thought and deliberation are nothing more than products of brain processes—if the mind is a natural phenomenon—then every action performed by humans is futile, and all human language is reduced to mere gibberish. In other words, according to the logic of (b), humans could no longer engage in moral evaluation, criticism, accountability, or appeals regarding anything at all. Just as we cannot hold lightning accountable for striking someone, no human could be held responsible for any action, regardless of its social implications. If this reasoning holds, ethics, history, literature, and the arts would be reduced to collective delusions, and sociology and law would need to be abolished. With this line of thinking, formal logic—since it was invented by humans—along with symbolic logic-based pure mathematics and physics, and all the scientific and engineering disciplines reducible to physics, would also be deemed meaningless. Even metaphysics would devolve into mere nonsense. Ultimately, under the claims of (b), everything humans do becomes a grand exercise in futility. How horrifying and absurd a notion this is! Furthermore, (b) suffers from a fatal logical inconsistency. Suppose a person A claims to hold the stance of (b). They could assert that the mind is dependent on the physical world, meaning that a mind, as an abstract entity independent of the physical world, does not exist. However, by this logic, the “self (I)”—which is also an abstract entity independent of the physical world—cannot exist either, and physical world-dependent abstract entities must be mere meaningless collections of matter. Yet A, by considering themselves to have a “self,” is asserting (b). According to (b), the proponent A’s mind is also a physical world-dependent abstract entity, which makes A’s assertion meaningless. Therefore, A’s assertion ends up affirming and simultaneously denying itself. Most proponents of physicalism and epiphenomenalism inevitably find themselves trapped in such an impressive logical contradiction. This fundamental flaw is a primary reason why mainstream philosophers of psychology reject (b). The mainstream theories in neuroscience and psychology, which view consciousness and the mind as freely occurring information processing algorithms within the brain, also share this limitation. Meanwhile, emergentism (c), a stance that is somewhat antithetical to (b), offers a rather unique perspective. It posits that there exists a mind independent of the physical world, and that this mind has no causal relationship with physical entities dependent on the physical world. However, from the perspective of scientists, this notion may prompt an instinctive reaction of “What on earth is this nonsense?” Therefore, the main issue with (c) lies in how one could prove the existence of a mind independent of the physical world. For example, consider the concept of a zombie that appears frequently in horror films—a being whose consciousness has died but whose body continues to move. Such an entity does not exist in reality, nor can we create it to demonstrate its existence. Hence, these arguments, based solely on the possibility of existence, may appear to be metaphysical, if not outright nonsensical.

The Causal Exclusion Argument can be used to summarize this debate in a simple diagram. Specifically, if a neural state (NS) induces (supervenes upon) an experiential state, and if a neural state (NS*) induces (supervenes upon) an action, then according to (a), 1) = NS and 3) = NS*. If we assume that NS* is the cause of an action and that the experiential state exists, then the experiential state induced by NS has no causal influence on the outcome. Conversely, if we assume that the experiential state does not exist, then it is merely a physical state—NS. Emergentism, particularly substance dualism, renders any claim in this scenario meaningless, no matter which option is chosen. As a result, this introduces a significant flaw into any justification of mental causation within philosophical psychology.