Physicalism versus Naturalism
Why We Reject the Former and Embrace the Latter
This blog was co-authored with Professor John Vervaeke.
We are scientists. We believe that there is only one world, the natural world. We also believe in the power of the scientific enterprise to yield deep truths about the nature of the universe that transcend the knowledge of “local” cultures.
We believe in a deep ontological continuity across the stack of complexification. We believe science has traced that ontological continuity in a convincing manner, both “back” to the origins of our observable universe at the Big Bang and “down” into molecules and atoms into particles and, finally, quantum fields.
And we believe that psychology and cognitive science should be consistent with biology which, in turn, should be consistent with chemistry which should be consistent with physics. We also believe in the causal closure of physics and that everything that is real ultimately “supervenes” on the physical.
And, yet, despite all these assertions and commitments, we reject the label physicalism (as well as materialism) to describe our views.
Instead, we are ontological naturalists. More specifically, we are Extended Naturalists (EN). As we have laid out in the Cognitive Science Show Transcendent Naturalism, EN is a new philosophy of mind and science. To see why we reject the label physicalism, we need to zoom out and see the current state of our knowledge and consider how we got here.
Materialism/Physicalism: The Dominant Position in Science and Philosophy
When it comes to philosophy of mind and science, physicalism is the dominant position. The Closer to Truth executive producer, Robert Kuhn, recently provided an excellent overview of the “landscape of consciousness,” and it demonstrated the primacy of physicalism in how most philosophers and scientists approach consciousness.
To understand the doctrine of physicalism, it is helpful to clarify its relationship with materialism. Materialism is the older term, although as the Kuhn review makes clear, it is still preferred by many. Materialism emerges as natural science splits from natural philosophy gets consolidated around Newtonian physics. Materialism can be considered the view that there is only one world, and it is the material world. The simplistic view is that materialism means that “everything is matter.”
In academic circles, materialism evolves into physicalism in the back half of the 20th century. This happens for several reasons. One was that new arguments emerged regarding ways of framing causal closure and supervenience (see here) that provided a compelling argument for the claim that there were no “non-physical” causes or properties. That is, to the extent that something caused something or had specifiable properties, those needed to be physically instantiated in some way.
A second reason the shift from materialism to physicalism happened was because advances in modern physics expanded our view of physical reality. Modern physics shifted the picture, such that “matter” was no longer considered to be fundamental. Rather, energy and quantum fields reside “beneath” matter, so materialism does not serve as a good description.
This latter point gives rise to one of the great questions of physicalism, which pertains to how to conceive of the term. Does it relate to a commonsense view of “physical objects”? Or does it relate to the theories of physics and the ontological picture of the world derived from physicists? If the former, how should physical objects be defined? If the latter, what about the fact that our physical theories are incomplete and change, like they did in the 20th century? And, finally, what, exactly, does it mean to describe or explain consciousness via a physicalist lens?
Physicalism grapples with these questions and does so in a way that renders it highly ambiguous (see Strawson for a strong critique). We will return to this point.
First, though, there is a deeper point that gets at the core of our criticism of the label, which pertains to the core grammar that emerged for understanding the world in the wake of the scientific Enlightenment.
Physicalism is Defined by the Enlightenment Gap and Its “Matter vs Mind” Grammar
Kuhn characterized his review of the landscape of consciousness as focusing on what consciousness is, rather than how it works. As Kuhn stated, the review is concerned with the “classic mind-body problem.” The mind-body problem has its most specific formulation with the hard problem of consciousness (i.e., the mystery of how subjectivity arises from brain states). The incredible diversity of opinions makes clear the problem has not been solved.
We believe there are two aspects of the mind-body problem that need to be separated. One problem pertains to clarifying exactly how subjective conscious experiences emerge in the context of brains. We consider this to be the narrow aspect of the problem, and see it mostly in neurobiological engineering terms. Unlike some commentators who claim this remains a complete mystery, we believe science has generated significant knowledge about this problem. At the same time, it also is the case that there remain some important aspects of it that are somewhat mysterious.
However, we do not see the neurobiological aspects of the hard problem to be the primary problem. There is a significantly larger mind-body problem, which we call the Enlightenment Gap. It can be considered the “top half” of the hard problem of consciousness, in contrast to the “bottom half” framed by the neurobiological engineering problem. It can be framed as the philosophical or metaphysical aspect of the problem.
The top half of the mind-body problem refers to the inability of modern knowledge systems to place mind in relationship to matter, and objective scientific knowledge in relationship to subjective and social knowledge. Given all the philosophical considerations and different approaches that Kuhn reviews, it is clear that there is much more at play than research questions about how the brain produces subjective experience. We are missing a larger frame of understanding because we are lost in the long shadow cast by the Enlightenment Gap.
The Enlightenment Gap emerges as natural philosophy splits off from Christianity, and gets consolidated as natural science grounded in Newtonian physics. A major reason why is because Newtonian mechanics essentially depicts the world as a bunch of atoms in the void, behaving in a deterministic way. In addition, as classical physics consolidates around the laws of conservation of things like energy and momentum. This results in something called “causal closure.” This means that all causes are going to be physical in some way. This picture of the physical world is hard to square with the domain of the mental.
There are also developments in philosophy that add to the confusion. Immanuel Kant synthesizes the rationalists and empiricists in a series of works that became the starting place for much of Western philosophy. Kant’s Transcendental Idealism emphasizes how we know about the world via the categories of the human mind. But it splits the world in the “thing-in-itself” and human phenomenology. In other words, we get a metaphysical split between being (i.e., the world as it exists) and knowing (our phenomenological understanding).
The combination of the methods and epistemology of natural science, the ontology of Newtonian physics, and the way modern philosophy was shaped by Kant gives rise to the great bipolar split of the Enlightenment. It is a split that divides the world into the domains of the physical and the mental. The split happens epistemologically (objective versus subjective knowing), ontologically (matter versus mind), and metaphysically (being versus thinking).
This split was recently described by the neuroscientist Christoph Koch as follows:
Western philosophy of mind revolves around two poles, the physical and the mental — think of them like the north and the south pole. There’s materialism, which is now known as physicalism, which says that only physical really exists, and there is no mental; it’s all an illusion…Then there’s idealism, which is now enjoying a mini-renaissance, but by and large has not been popular in the 20th and early 21st century, which says that everything fundamentally is a manifestation of the mental.
Thus, the split identified by the Enlightenment Gap is what gives rise to the physicalism versus idealism split (i.e., all matter versus all mind). It can also be seen in dualism (i.e., the world is made up of both matter and mind) and panpsychism (i.e., mind goes all the way down with matter).
With this summary we arrive at the first major reason we reject physicalism. It is essentially defined by the matter versus mind split. For a host of reasons, Extended Naturalism rejects this split. In contrast to a grammar where matter is defined against mind, EN extends our view of nature and of human consciousness to see how they can fit together. In addition to physicalism being defined by a fundamentally problematic grammar, we argue that it is an ambiguous and confusing doctrine that should be replaced by an ontological naturalism, of which EN is a specific kind.
What does Physicalism actually mean?
Robert Kuhn’s review makes clear that materialism/physicalism is the dominant approach in science. But the review also makes clear that physicalism means many different things.
To understand what it means, we can start with the most general version of physicalism. To do so, we simply need to trace it to its historical roots as natural philosophy in the Christian worldview. The standard interpretation provided by Christianity is, of course, a substance dualist worldview. There is the natural world that we live in, and the supernatural world of God (and angels). Our soul is given by God, it breathes life and consciousness in us, which ultimately returns to the supernatural plane after we die.
In Christianity, natural philosophy was about the natural world, as opposed to the supernatural world. The task was to discover “God’s laws” as he set them in motion. As natural philosophy evolved into natural science, then we get the shift from a “substance dualism” (i.e., two worlds, natural and supernatural) to a one world monism. This gives us the most general meaning of physicalism, which is that there is only one world and it is the natural world.
The proper term for this assertion is ontological naturalism. Now, some philosophers equate physicalism with ontological naturalism. For example, here is the philosopher David Papineau making this point. However, we consider this to be a problem. To start, if physicalism means one world naturalism, then we should just go with ontological naturalism because it is much clearer. Miłkowski makes precisely this point, writing:
Physicalism must be committed to the view that all objects are physical, and that implies that objects mentioned in special sciences, for example, are reducible to physical. [Ontological] naturalism doesn’t have to embrace this view. This is not to say that naturalism is necessarily anti-reductive; on the contrary, it has to imply that all objects are natural objects, and that means that they are reducible to natural objects. The main difference is that narrow physicalism implies unity of science, and naturalism can remain neutral towards it, neither denying nor accepting it.
This brings us to our second point for rejecting physicalism. We agree with the most general version of physicalism (i.e., there is only one world, the natural world), but we think the it should be referred to by its proper name, ontological naturalism.
However, as Miłkowski suggests, physicalism often means more than the one world naturalist position. First, as the grammar of the bipolar disordered split reminds us, the concept of the physical is tied up with the mental, such that the physical, meaning objective and material, is often considered to be the polar opposite of mind, which is subjective and “non-material.”
Second, unlike naturalism, physicalism carries strong connotations of physics, especially the way physical theory describes reality. With this linkage to physical theory made, we can then move to the three primary variations on physicalism, which relate to how to conceive of it in terms of reductionism and emergence.
Reduction and Emergence in Physicalism
There are three broad positions on reduction and emergence within physicalism. First, we have reductive physicalism. This is the project of attempting to reduce everything to lower and lower levels on the ontological stack. One famous example is “eliminative materialism” by Paul and Patricia Churchland. This tries to eliminate folk psychology and replace it with talk of brain-behavior relations. John Bickle similarly offered a “ruthless reduction” of mind-to-molecules, completely eliminating scientific psychology and replacing it with chemistry and neuroscience. We also have scientists like Sean Carroll saying that the only things that are “fundamentally real” are the elementary particles, and the neuroendocrinologist Robert Sapolsky saying that the only real determinants of behavior are biology and the environment.
There are also epistemologically reductive positions that try to “reduce” our understanding of the world to science and its third person perspective. This was the late philosopher Daniel Dennett’s approach. He even questioned whether qualia (i.e., subjective experiences of things like redness) really existed and characterized subjective experience as a kind of illusion. His solution was to ground one’s understanding in a third person, scientific view of the world.
EN rejects reductive physicalism, both the ontological and epistemological versions. However, many physicalists are not strict or “greedy reductionists” as Dennett would call them. A reason immediately presents itself, which is that strong, simplistic forms of physical reductionism can quickly become absurd. For example, consider the project of trying to reduce the behavior of economic markets to the movements of atoms. Essentially no one does this or advocates for it.
This brings us to the concept of emergence. Virtually everyone in science and philosophy acknowledges emergence in some form or another. As Kuhn’s review notes, there are generally two positions on emergence in the philosophy of mind, one “weak” and one “strong”.
Weak emergence recognizes both that novel properties emerge, and to make sense of them we need epistemological categories that describe them. Continuing with the example above, economic markets have their own properties and must be studied as such. On this account, we have chemistry, biology, psychology, and the social sciences, in addition to physics, because of emergent properties, and practical realities force us to examine entities at that level of organization. This is probably the standard position in physicalism.
However, it is unclear what, exactly, weak emergence says about the world ontologically. For example, is it the idea that everything ultimately reduces ontologically to the bottom layer of physics, as Sean Carroll argued? This is not clear, and weak emergence is ambiguous regarding what it says about the ontology of nature.
There is also nonreductive physicalism, which is so named because it embraces the strong form of emergence. Strong emergence is the claim that there are emergent properties that both have causal powers above the lower levels and that those properties “can never be explained in terms of properties of lower levels, not even in principle, no matter how ultimate the science” (Kuhn, 2024).
We do not think strong emergence is clear in what it proposes. We agree that higher ontological layers in nature are not reducible, even in theory, to the causal explanatory frameworks of the layers beneath them. However, we do not consider this a mystery. And, we embrace top-down causation. However, we do not think it is a conceptual problem to do so, nor is it mysterious (i.e., our ontology of science makes obvious why top-down causation is part of nature).
To sum up this section: There are confusing, inconsistent positions pertaining to reduction and emergence that render the meaning of physicalism ambiguous. In addition, reductionism, weakly emergentist, and strong emergentist positions are problematic in the picture they offer. This brings us to our next critique, which is that this ambiguity spreads into our everyday understanding of the world.
The “Standard View” of Physicalism is Misleading and Confusing
In his book, Physicalism, Daniel Stoljar summarizes what he calls the “standard view” of physicalism. This is the set of claims that (a) everything is physical and (b) we tend to think of the world as being split between the physical and the mental and thus (c) because of a and b, the world of the mental is really an illusion and is just made up of physical stuff after all. This is a problem because this set of ideas seems to be in direct conflict with commonsense.
He writes:
Some of the claims which physicalism might be thought to be inconsistent with or in tension with are:
• that people perceive things and have bodily sensations of various kinds, e.g. tastes, cramps, itches, nausea;
• that people speak and think about the world and about each other;
• that at least some words have meaning;
• that people’s bodies, and physical objects in general, are colored, textured, have various tastes, and emit sounds and smells;
• that people have reasons for thinking and acting as they do, and that those reasons may be subjected to normative (including moral) scrutiny;
• that people participate in group decisions and actions, and in turn the actions of these groups impact on the individuals who constitute them;
In order to appreciate the importance of these claims, try to think for a moment how things would be if they were false — that nobody thinks or feels, or says anything meaningful, or that ordinary physical objects are not solid or colored, or that there is no freedom of action or social agency or mathematical knowledge. It is obvious when you think about it that these claims and others like them are central to life as we live it; they are, as I will say, the presuppositions of everyday life. So in effect what we are being asked to accept by the standard picture is the idea that there is a prima facie conflict between the presuppositions of everyday life on the one hand, and a thesis we have overwhelming reason to believe — i.e. physicalism — on the other.
Stoljar goes on to explain that it depends on how both physicalism and these commonsense claims are interpreted to decide if they really are in conflict. For example, if one adopts the perspective of a strong reductionist, then there are good reasons to believe that there is a conflict. Indeed, Eliminative Materialism is very much about transforming our way of talking away from folk psychology and into brain-behavior language. However, the conflict is much less clear if one adopts an emergentist perspective. It also, of course, depends on how one is thinking about these commonsense claims.
For us, the ambiguity rendered by the standard view is enough to make the point: The basic structure and grammar of “physicalism” results in deep confusion about how to scientifically and naturalistically understand the mental and the everyday world of human consciousness.
Importantly, this confusion regarding the mental does not emerge under the label ontological naturalism. Here we can again return to Miłkowski who offered an excellent justification for ontological naturalism:
Ontological naturalism appreciates that we have multiple ways of access to objects on various levels of their organization. Far from denying the role of physics in contemporary science, it is able to integrate special sciences in the realistic account of human knowledge. There is no better source of knowledge than science, and there is no evidence that all special sciences will converge into ideal physics.
Of course, as those who follow UTOK know, we have the ToK System to validate this assertion.
In sum, physicalism is a deeply problematic term because: (a) it is intimately tied to the matter-mind bipolar split that gave rise to the Enlightenment Gap; (b) it results in a grammar that is difficult if not impossible to clarify in relationship to the mental; (c) it is unclear regarding whether it refers to general physical objects or requires commitment to physical theory; (d) it results in problematic approaches to reduction and emergence (i.e., reductive physicalism, weak emergence, and strong emergence); and (e) it is confusing to communicate and unclear how it aligns with commonsense.
Ontological naturalism is different. It is clear in that it means that there is only one world, which is the weak, “good” claim that physicalism makes. Second, ontological naturalism is not entangled in the matter-mind bipolar split, nor does naturalism evoke the polar opposite of the mental. It also does not make any commitments to physical theory. At the same time, it is consistent with the general insights of physicalism pertaining to causal closure and supervenience.
Extended Naturalism: A Powerful New Approach to Ontological Naturalism
In regards to emergence and ontology, as well as aligning our philosophy with our everyday experience of reality, these elements are addressed by EN. As this blog lays out, EN comes with a clear ontological picture of the world that is directly consistent with natural science. Via the ToK System it divides the natural world into five ontological layers (i.e., Energy-Information; Matter-Object; Life-Organism; Mind-Animal; and Culture-Person), and via the Periodic Table of Behavior, clarifies why the latter four layers can be further divided into three levels each, resulting in 12 “primary” ontological levels.
Moreover, via the combination of the emergence of properties combined with the emanation of constraints coupled to logical arguments about ontology, EN gives us a clear picture of complexification in nature, one that is more specific than weak emergence but also avoids the mystery associated with strong emergence. UTOK’s Big History 2.0 taxonomy of emergence/emanation gives additional clarity.
Finally, as this blog lays out, current approaches to consciousness split the “nature” question from the “function” question. The nature question is the philosophical question of how consciousness fits into the furniture of the universe and it gives us the categories like physicalism, idealism, and panpsychism. In contrast, the function question is how consciousness operates in the world.
As we laid out in Untangling the World Knot, we believe this split is problematic and leads to much confusion. As metatheorists in psychology and cognitive science, we are deeply concerned with both the nature and function question and see them as intimately intertwined. In addition, we have developed metatheoretical systems that allow us to see how everyday human processes, such as realizing relevance, investing in activities, influencing others and justifying our actions, are all related to human consciousness and part of the “natural world” broadly defined to include human behavior.
Conclusion
In sum, we reject the label physicalism for a host of reasons. Ontological naturalism is a better and clearer term for conveying what needs to be conveyed. And it avoids the problematic implications and entanglements that come with physicalism.
From there, we can move to Extended Naturalism, which fills in the gaps and provides for us a coherent naturalistic ontology that also makes sense of human consciousness in a powerful way that does not contradict or eliminate the presuppositions of everyday life.
For all these reasons, we reject physicalism and embrace Extended Naturalism. We encourage others with similar worldviews and philosophical inclinations to do the same.
