I just turned in the first paper for my current philosophy class, “Mind, Matter, and Meaning.” I like to think my philosophy writing style has gotten better, but that might be tempered by my lack of depth on the topic. The paper isn’t very long, but I also didn’t manage to get a lot of content into it.
Do We Understand Physicalism?
When considering consciousness, we often distinguish between the physical aspects of firing neurons and the mental aspects of how being alive actually feels. A further consideration is whether the physical and mental are the same–as physicalists believe–or distinct–as dualists believe. In “What Is It Like to Be a Bat?” Thomas Nagel claims that “it would be a mistake to conclude that physicalism must be false” and that “physicalism is a position we cannot understand because we do not at present have any conception of how it might be true.” These claims might seem inconsistent, but I will explain how Nagel would resolve them. I will then consider meaning of his second claim and explain why I believe it is false.
Before addressing those topics, I want to clarify two points. First, physicalism, as defined by Nagel, states that “mental states are states of the body; mental events are physical events.” Just as Barack Obama and the current President of the United States are distinct names that correspond to the same object, mental states and physical states correspond to the same phenomena. Second, Nagel is ambiguous about what physicalism he believes we cannot understand. He writes, “we do not at present…”, so he could mean that we cannot understand our current version of physicalism, or that we cannot and will never understand the complete theory that physicalism might one day become. While the latter is an interesting topic, I believe that Nagel intends to say that we don’t actually understand physicalism as it is now. Thus, I will abbreviate his second statement as “we can’t understand physicalism now.”
At first glance, Nagel’s two claims, that physicalism doesn’t have to be false and that we can’t understand physicalism now, don’t make much sense together. Roughly, the criticism is that the two claims are mutually exclusive and cannot be simultaneously true, which is valid if we can show that when one is true, the other must be false. So let’s assume we can’t understand physicalism now. If we can’t understand physicalism now, then we don’t actually know what we mean when we talk about “physicalism.” So physicalism is meaningless. For physicalism to be true, it must accurately explain consciousness, and a meaningless theory can’t explain anything. Thus, if physicalism isn’t meaningful, then it is false. The argument concludes that the claim that we can’t understand physicalism now implies that physicalism is wrong.
Nagel would likely respond that this argument is invalid. The criticism asserts that a theory we cannot understand is meaningless, yet earlier in the essay, Nagel specifically addresses what we as humans can understand. He states, “My realism about the subjective domain in all its forms implies a belief in the existence of facts beyond the reach of human concepts.” There are certain facts about the universe that, because of our limited human point of view, we will never understand. Because our scope is limited, we cannot conclude that topics we don’t understand must be false. Quite the opposite, Nagel argues some of those unknowable topics must be true. Although he presents the argument within the scope of explaining the differences in subjective experience, his assertion applies equally here in the debate about these theories.
Following the same argument as that of the criticism, we can start with the same assumption that we can’t understand physicalism. This only implies that, to us humans, physicalism is meaningless. Aliens, however, may exist to whom physicalism is very meaningful and understandable. We may never understand physicalism as it truly is, but according to Nagel, we should accept that such facts do exist. Because physicalism may not be entirely meaningless, we cannot authoritatively claim that it is false from what we know. Granted, this argument is somewhat weak as it doesn’t necessarily prove that physicalism is true; it only shows that we are uncertain about the truth of physicalism. Fortunately for Nagel, that is his original claim. Because both of his two claims can both be true simultaneously, they are not mutually exclusive. Note that this argument still works even in a stronger interpretation of the first claim, where Nagel suggests that physicalism is consistent with the rest of his essay. In this case, we still cannot undoubtedly know that physicalism is false for the same reasons above.
Having dealt with the apparent inconsistency with these two claims, we can now consider the truth of his second claim, “It would be truer to say that physicalism is a position we cannot understand because we do not at present have any conception of how it might be true.” Without delving into the individual clauses, we can first analyze the structure of this claim. With some rearranging, his statement implies that if we have a conception of how physicalism might be true, then we would then be able to understand it. In his essay, the following paragraphs present a counter-argument to the belief that we can understand physicalism directly with the “mental states are physical states” definition. Instead, I will argue that a conception of how physicalism might be true does not necessarily imply that we can understand it.
The more generalized form of his statement is that if we have a conception of how X might be true, then we would then be able to understand X, where X can be anything. We can prove this statement false with a counter-example where the antecedent is true and the consequent is false. Having shown the existence of a counter-example, we can no longer broaden the claim to all objects, including physicalism. I will use string theory as an example of something that we understand but have no conception of how it could be true.
Under Nagel’s definition, one way that we can understand something is to have a “theoretical framework.” Although he doesn’t specify what is sufficient for a theoretical framework, he uses the theoretical framework to determine whether one thing “is” another. Such a framework can break down a concept into understandable and identifiable parts that can act as a common language between two concepts. For string theory, that theoretical framework is math. String theory was originally based upon math and is popular for the elegance of the numbers. At least as far as string theory requires, I will assume that we understand math. Its current content has been developed through human thought and is not dependent on any experience with the physical world that is more fundamental. In the equations dealing with one-dimensional strings in multi-dimensional space, we can describe a significant portion of phenomenon in consistent way with what we observe. Because we can definitively say whether some other theory is or is not string theory, string theory satisfies Nagel’s conditions for understanding.
Although we understand string theory, we still do not know how it could be true. A fundamental problem with string theory is that we have no way to prove whether it is correct or not. With Newtonian mechanics, we can conduct experiments observable by the human-eye to verify our theories. On a quantum level, physicists have worked with particle accelerators to determine the existence of sub-atomic particles. On a string level, however, we have yet to develop a feasible method to directly test whether such strings exist. Even our visualizations of strings are incomplete and unsubstantiated. Simply, we currently don’t even have a method for how we could determine if string theory is true. Without it, we can’t even begin to consider how it might be true.
Given the example from string theory, we can see that there exists at least one theory that we understand yet have no conception for how it could be true. Admittedly, this notion doesn’t tell us much. It’s a fallacy to believe that we don’t currently understand physicalism on this basis, yet we haven’t proven that we do understand physicalism. Having denied Nagel’s conditions for understanding, we can’t use Nagel’s definition of understanding to determine whether we understand physicalism. Although it is not meant to be definitive, I want to propose a different condition for “understanding” so that we can say that we understand physicalism. I will define “understanding” as the ability to express and discuss an idea in a meaningful, accurate manner. The obvious ambiguity with this definition is what I mean by “meaningful.”
In his essay, Nagel points out that we can have proof for something without actually understanding it. Similarly, he would likely believe that we can discuss some concept without actually understanding what it is. What I think is more important is the meaning in context for how we discuss something. For example, if I was explaining baseball to a newcomer, I could say that I understand baseball because I can explain the rules and contrast them with other games. If I were discussing baseball with a physicist, however, I wouldn’t understand baseball because I don’t know exactly why a curveball curves or how the shape of the ball affects its trajectory. For physicalism, we must ask what the most important context is to judge whether we understand it. Although we might hope to understand it better in the future, we now understand it well enough to contrast with dualism, which, most simply, argues that physical states are not mental states. So with this definition of “understanding,” it seems that we can generally say that we understand physicalism.
With these two claims, that physicalism isn’t wrong and that we can’t understand physicalism now, Nagel avoids taking a hard-line position on the dualism versus physicalism debate. Although his statements may seem contradictory, I think it more likely that Nagel intended his essay to be read more as an observation instead of a defense for any particular view. Even so, his conditions for understanding physicalism are wrong, so perhaps we do understand physicalism in a different sense of understanding.
Nagel, Thomas. “What Is It Like to Be a Bat?.” The Philosophical Review 83 (1974): 435-450.