This is a post by Marcelino Botín (University of Barcelona) and Markel Kortabarria (University of Barcelona)
Consciousness is a rare beast. It is the aspect of reality with which we are most intimately acquainted, yet itremains strikingly resistant to scientific characterization. Classic thought experiments such as Mary in the black-and-white room suggest that one can possess complete scientific knowledge about the brain and still lack knowledge of what consciousness really is. Antiphysicalists take this to indicate that consciousness is fundamentally distinct from the physical. The traditional challenge for physicalists, then, is to explain how consciousness could be physical, despite our inability to account for it in the same way we explain other physical phenomena.
The most influential response is the Phenomenal Concept Strategy (PCS). According to PCS, although consciousness is just a brain state, we have a special way of thinking about it from the first-person perspective, through so-called phenomenal concepts. Unlike physical concepts, which present their referents in functional or structural terms, phenomenal concepts employ a purely experiential mode of presentation. Thinking about an experience via a phenomenal concept is like recognizing the face of a friend. You don’t need a description to identify it; you just see it. That’s how phenomenal concepts work: they latch onto the feeling of an experience. Because phenomenal and physical concepts present their referent in such radically different ways, they create the false impression that experiences and brain states are distinct, and moreover that one cannot be explained in terms of the other.
Antiphysicalists argue that this is insufficient. Even if PCS can explain why Mary lacks knowledge of pain experiences while in the room, it seems unable to account for the substantive discovery she makes upon leaving it. If Mary learns something genuinely new, then her newly acquired phenomenal concept must latch onto a property not already captured by her complete physical knowledge. But if so, the relevant property appears to be non-physical.
A promising solution appeals to a non-reductive form of physicalism built around the notion of grounding. In brief, grounding is a now-fashionable relation of metaphysical determination, invoked by those who conceive of reality as hierarchically structured. It captures the idea that some facts obtain in virtue of more fundamental facts, in something like a productive metaphysical sense. For the grounding physicalist, facts about pain are distinct from, but grounded in, underlying physical facts. This allows phenomenal concepts to latch onto genuinely new properties. Nevertheless, because phenomenal facts are grounded in more fundamental physical facts, they still qualify as acceptably physical.
Unfortunately, grounding physicalism faces a further challenge. Some antiphysicalists argue that phenomenal concepts do more than refer: they also reveal the essence of their referents. The idea is that undergoing an experience places one in a position to grasp what that experience essentially is, which is captured by the phenomenal concept. This is the so-called revelation thesis.
Revelation poses a problem for physicalism across the board. When we attend to the feeling of pain, nothing in that reflection suggests that being in pain consists in occupying a physical or functional state; on the contrary, pain appears to be purely phenomenal. One might expect grounding physicalism to fare better, since it rejects strict identity between the phenomenal and the physical. Yet the view faces a difficulty arising from the idea that grounding relations are essence mediated.
To get an intuitive grip, consider how facts about the arrangement of parts ground the fact that a table exists. Plausibly, this relation holds in virtue of the essence of a table: what it is for something to be a table is for it to be constituted by parts arranged in a certain way. Now apply this to the grounding physicalist proposal. If grounding is indeed essence-mediated, and physical facts ground phenomenal facts, then phenomenal properties must have physical essences. But if the revelation thesis is correct, phenomenal concepts present these properties as having purely phenomenal essences. It follows that physical facts do not ground phenomenal facts.
How should the grounding physicalist respond? Rejecting revelation is unattractive, since it would imply that reflecting on what pain feels like tells us nothing about what pain is, pushing physicalism toward a form of anti-realism. Two strategies remain: reject essence-mediation, or reconcile it with revelation.
One way of implementing the first strategy is to appeal to grounding laws—metaphysical principles linking grounds and groundees. On such a view, facts about pain obtain in virtue of facts about underlying physical facts due to a psychophysical grounding law that specifies that whenever the physical property is instantiated, the corresponding phenomenal property is instantiated for that reason. Since this approach rejects essence-mediation, it can coherently maintain that phenomenal properties lack physical essences.
What about the second strategy? While there is a sense in which the essence of pain is just how it feels, this does not justify the claim that pain is purely phenomenal (i.e., non-physical). An analogy helps. For something to be fragile is to be disposed to break under certain conditions. This captures something essential about fragility: to be fragile just is to be disposed to break under certain conditions. However, this characterization does not reveal every essential aspect of the property, in particular it tells us nothing about whether fragility is fundamental, or whether it is grounded in more fundamental facts involving a particular structural arrangement of atoms, such that fragility itself is essentially structural. Similarly, phenomenal concepts reveal only the superficial essence of experiences—what they feel like—without revealing their deeper essence: whether such properties are fundamental or grounded in physical properties.
To be sure both strategies face some worries. For instance, one might object that the first response comes uncomfortably close to dualism: both views posit a wide range of lawlike principles linking the physical and the phenomenal, while treating these domains as distinct. Still, grounding physicalism retains important advantages. Insofar as consciousness is grounded, it is not fundamental, yielding a sparser fundamental ontology. Moreover, the view avoids the worries about causal overdetermination that beset dualism. The second strategy, by contrast, threatens a resurgence of the explanatory gap. If the essences of grounds and groundees are such that the obtaining of one necessitates the other, it seems as we should be able to derive that if one obtains so does the other. However, this expectation arises only under a reductive understanding of grounding. If grounds and groundees are ontologically distinct, explanatory gaps are to be expected even in paradigmatic cases of grounding. Still, the phenomenal gap is especially puzzling. One way to explain its distinctive opaqueness is to appeal to a difference in epistemic access: our knowledge of the physical is causally mediated, whereas our knowledge of experience is immediate and non-causal. The distinctive mystery of the phenomenal thus reflects the unique way in which we access phenomenal facts.
All in all, grounding physicalism remains a view worth taking seriously. While it faces important challenges, it offers a flexible and theoretically attractive framework for reconciling the reality of consciousness with a broadly physicalist ontology. In our view, it is still very much worth a bet.
This was a brief snipet of some of the ideas we disucss in our paper “Grounding Physicalism and the New Challenge of Consciousness,” recently published in Erkenntnis. The article is available for free here. Our work has been supported by María de Maeztu Unit of Excellence grant CEX2021-001169-M (funded by MICIU/AEI/10.13039/501100011033).
Marcelino Botín is a postoctoral researcher at the University of Barcelona TEXT
Markel Kortabarria is a postoctoral researcher at the University of Barcelona where he works as a member of BIAP and the LOGOS group. His research focuses on the notion of metaphysical grounding, its applicability and its relation to other notions such as fundamentality and metaphysical explanation.
Open Philosophy 