Clarifying the naturalist commitments of some panpsychists

‘Naturalism’ is an ambiguous term, as Leidenhag acknowledges. Alas, when she attempts to clarify what is meant by ‘naturalism’, rather than discuss how defenders of panpsychism have used said term, she discusses how some philosophers who reject panpsychism have defined ‘naturalism’. This strikes me as an unfortunate oversight on her part.

Leidenhag begins with methodological naturalism, which, in its strongest forms, takes the sciences as providing the only route to knowledge about the nature of reality. She takes methodological naturalism to lend itself to the acceptance of ontological naturalism, which most philosophers take as the claim that the only existents are the constituents of the universe, which is a closed system. Leidenhag asserts that a commitment to ontological naturalism ‘leads to physicalism’ (ibid., 65). She adds that, ‘[i]n its negative form naturalism is a commitment to atheism (with negotiating room left for pantheism)’ (ibid., 68). She maintains that ‘Panpsychism cannot be naturalistic in any of the senses outlined above’ (ibid., 66).

Contra Leidenhag, I take it that panpsychism can be naturalistic. More specifically, panpsychism is compatible with versions of both methodological and ontological naturalism. Given that Leidenhag focuses a fair amount of attention to the work of David Chalmers, Thomas Nagel, and Galen Strawson (see ibid., 50–60), I will stick to what these three have said about naturalism in the remainder of this section.

It is best to begin by getting clear on the species of naturalism with which panpsychism would be incompatible. Nagel is the only one of the philosophers mentioned who has critiqued naturalism. His target is not naturalism simpliciter. He critiques versions of methodological and ontological naturalism that would exclude the existence of entities that cannot ‘be fully explained by physical science’ (ibid., 14). He refers to this species of naturalism as ‘materialist naturalism’ (ibid., 13). What Nagel targets is christened ‘physicSalism’ by Strawson, which is ‘the view that the science of physics can fully characterize the nature of concrete reality, at least in principle’ (ibid., 134). Panpsychism is clearly NOT compatible with naturalism qua physicSalism.

How defenders of panpsychism have characterized the versions of naturalism they endorse varies. Chalmers is well known for advocating ‘naturalistic dualism’.Footnote ² His proposal is a version of property dualism on which phenomenal properties are fundamental. They are quiddities, being purely categorical. They contingently ground the dispositional properties of objects whose activation we measure in physics. Chalmers maintains that his view is naturalistic

Chalmers's account involves a commitment to modest versions of both methodological and ontological naturalism. Regarding methodological naturalism, Chalmers assumes that what we can know about consciousness is explainable in terms of fundamental entities and the laws of nature. And it is ontologically naturalistic given that everything posited by his metaphysic of consciousness is a constituent of the universe. As he notes, ‘nothing about this view contradicts anything in physical theory; rather, it supplements that theory. A physical theory gives a theory of physical processes, and a psychophysical theory tells us how those processes give rise to experience’ (ibid., 127–128).

Nagel evinces a commitment to methodological and ontological naturalism. That said, Nagel is not clearly a panpsychist. He explicitly endorses a version of neutral monism on which mental and physical properties are reducible to a more fundamental type of neutral property that ‘explains both the physical and the mental’ (Nagel (Reference Nagel2002), 234). He writes that, ‘[p]anpsychism is, in effect, dualism all the way down. This is monism all the way down’ (ibid., 231). I will not dwell on the details of Nagel's metaphysic of mind, especially given the difficulties of knowing how best to understand his view.Footnote ³ What is important for my purposes is that he insists that the reason for accepting it, ‘like the reason for believing in the reality of any other theoretical entities, will be inference to the best explanation’. He adds that, ‘[w]e hypothesize that there are things having the character necessary to provide an adequate explanation for the data, and their real existence is better confirmed the wider the range of data the hypothesis can account for’ (ibid., 233). The methods we should use for determining whether it is reasonable to accept this model of the mind are characteristic of the sciences. This is at least a modest methodological naturalism as he assumes that the epistemic standing of his account depends on how explanatorily fecund it proves to be with respect to various data. He rejects reductionism, but, as he notes, reducing everything to physics is not a requirement for scientific explanations. As for ontological naturalism, none of the existents he posits are non-natural or supernatural. They are the objects and properties that underlie everything in the physical universe. As Nagel notes, ‘mind is not just an afterthought or an accident or an add-on, but a basic aspect of nature’ (Nagel (Reference Nagel2012), 16, emphasis added).

Finally, Strawson initially defines ontological naturalism negatively, as denying the ‘concrete existence of anything supernatural or otherwise non-natural’ (Strawson (Reference Strawson2012), 126). More positively, he writes that his ‘substantive conception of the natural’ maintains that ‘concrete reality is entirely physical in nature’. Hence, Strawson endorses a physicalist version of ontological naturalism (ibid.). He endorses what he calls a ‘realistic species of methodological naturalism – the view that inquiry into the metaphysically contingent nature of concrete reality should always proceed as far as possible in accord with the methods of the natural sciences’ (ibid.). As mentioned before, Strawson rejects what he calls ‘physicSalism’. The watershed difference between Strawson and proponents of physicSalism is over whether physics can ‘possibly convey the nature of everything that concretely exists’ (ibid., 134). Physics is limited in what it can tell us about the whole nature of concrete reality, according to Strawson. The fact of experience is ‘the most certainly known natural fact’ and ‘the most certainly known physical fact’ (ibid.). Realism about experience, Strawson argues, is ‘the starting point of real naturalism’ (ibid.). Elsewhere, he argues that if all stuff is physical and ‘experientiality is a kind of stuff’, then experientiality is physical and ‘the most natural and parsimonious hypothesis is that all concrete reality is experiential’ (ibid., 320).

The sense in which all three authors have endorsed naturalistic views is minimally consistent with modest versions of methodological and ontological naturalism. While Chalmers presents us with a panpsychist property dualism, both Nagel and Strawson eschew any form of dualism in their metaphysics of mind.Footnote ⁴ None endorse the physicSalism that Leidenhag appears to assume is the outcome of endorsing naturalism. If I am right, then panpsychism is compatible with versions of both methodological and ontological naturalism.

Should panpsychists endorse theism?

Suppose panpsychism is compatible with naturalism. That does not imply that naturalism is a commitment of panpsychism. It is not clear that any metaphysics of mind is necessarily ontologically committed to naturalism (for instance, one may be a physicalist about the minds of creatures while endorsing theism). On the other hand, it is not obvious that any metaphysics of mind implies an ontological commitment to theism.

Recall the rather strong claims Leidenhag makes about the relation between theism and panpsychism. She denies that panpsychism strictly entails theism (Leidenhag (Reference Leidenhag2021), 173). But she asserts that ‘unbeknownst to most contemporary panpsychists, the arguments made in the recent turn to panpsychism invite or imply belief in a Creator’ (ibid., 81, emphasis added). I am uncertain about what sort of relation Leidenhag wishes to pick out by the term ‘imply’. I assume it must be material implication, which, while weaker than strict entailment, is a stronger relation than the mere consistency of the conjunction of two propositions.

Leidenhag takes as her starting point the anti-emergence argument for panpsychism presented by Nagel (Reference Nagel1979). Leidenhag takes it that the argument assumes the principle of ex nihilo nihil fit (‘nothing can come from nothing’) and the principle of sufficient reason. Nagel presents four premises ‘each of which is more plausible than its denial’, from which ‘[p]anpsychism seems to follow’ as the conclusion (ibid., 181–182).

1. 1. Material Composition: Any living organism is a complex material system.

2. 2. Non-reductionism: Mental properties are not physical properties and are not implied by physical properties alone.

3. 3. Realism: Mental properties are real properties of organisms.

4. 4. Non-emergence: There are no strongly emergent properties of complex system.

William Seager succinctly summarizes Nagel's reasoning as follows.

• P1. Consciousness is either a fundamental or an emergent feature.

• P2. Consciousness is not an emergent feature.

• C. Therefore, consciousness is a fundamental feature. (Seagar (Reference Seager, Brüntrup and Jaskolla2017), 232)

Assuming for the sake of argument that Leidenhag is right that Nagel's argument assumes the two aforementioned principles, it is natural to wonder what any of the foregoing line of reasoning has to do with theism.

Leidenhag maintains that the anti-emergence and cosmological arguments are isomorphic. Suppose this is correct. Both identify an ontological gulf between a particular state of affairs (specifically, an organism's possessing mental properties and the universe's existence) and some other state of affairs (specifically, an organism's possessing physical properties and the universe's non-existence). Leidenhag asserts that panpsychists rely on the principle of ex nihilo nihil fit regarding ‘the ontological divide between matter and mind when they reject [strong] emergence’ (Leidenhag (Reference Leidenhag2021), 82).Footnote ⁵ But she argues that while the anti-emergence argument provides an explanation of why there are minds in the universe, naturalist panpsychists unreasonably stop short of asking why there is anything at all.

In the interest of clarity, I will represent Leidenhag's reasoning as a simple modus ponens argument.

• P1. Panpsychist reasoning rejects brute contingencies.

• P2. If (P1), then the panpsychist should posit a Creator of the universe or hold that the universe is a necessary existent on pain of inconsistency.

• C. Therefore, the panpsychist should posit a Creator of the universe or hold that the universe is a necessary existent on pain of inconsistency.

I will focus on the consequent of (P2), which is a disjunctive claim, and argue that accepting its truth does not imply a commitment to theism (but I will also question whether we ought to accept it as true).

Consider the first disjunct: ‘the panpsychist should posit a Creator of the universe’. I will not rehearse the reasons for why the soundness of the cosmological argument would not commit one to theism. Those reasons should be well known to any readers of this journal. So even if we accept the truth of the first disjunct, nothing about its truth commits one to accepting theism. Thus, even if we grant that the panpsychist's assumptions and reasoning imply the existence of a Creator, it is not obviously the case that the Creator is the God of theism. In fact, if we duplicate the reasoning of the anti-emergence argument that Leidenhag endorses, then the Creator cannot be an altogether different kind of thing from what it causes, namely, the physical universe. A purely mental thing that is without any spatiotemporal location is very different from a universe that is extended (see Buckareff (Reference Buckareff2016)). Nagel notes that the problem with turning to theism to understand the natural world and our place in it is that it would not explain ‘how beings like us fit into the natural world’. He adds that ‘[t]he kind of intelligibility that would still be missing is intelligibility of the natural order itself – intelligibility from within’ (Nagel (Reference Nagel2012), 26). A supernatural being will not deliver the requisite intelligibility.

Turning to the second disjunct, the claim that ‘the universe is a necessary existent’ requires some clarification. What kind of necessity does Leidenhag have in mind? It cannot be logical necessity given that there is nothing contradictory about the universe not existing. It must be metaphysical necessity.

The naturalist will take ‘world’ to pick out the universe. The supernaturalist takes ‘world’ to refer to more than the universe. The supernaturalist assumes that the existence of the universe requires an explanation. Assuming actualism about the metaphysics of modality, the naturalist assumes that the universe is all there is.Footnote ⁶ To talk about it as existing necessarily may seem a bit like a category mistake to the naturalist. The space of metaphysical possibility is provided by the universe. But is the universe's existence in need of an explanation? That suggests that it is contained or nested in something larger, the world, understood as being more than the universe. This is precisely what the naturalist denies we have good reason to accept. As for whether something could come from nothing, no one is asserting that. I do not have the space to discuss models of the origin of the universe in contemporary cosmology. But no naturalist argues that the universe as it exists came from nothing (but the theist does!). Thus, depending upon how we understand what is being asserted by the claim that the universe is a necessary existent, the second disjunct either makes a category mistake and is false or it is a commitment of naturalism that is consistent with our best cosmological models.

My interlocutor may worry that I have ignored the principle of sufficient reason. For now, I will answer the way Nagel does (echoing Wittgenstein): ‘All explanations come to an end somewhere’ (Nagel (Reference Nagel2012), 22). The theist stops with a supernatural Creator God. The naturalist stops with the universe. What the panpsychist adds to this is teleology within the natural order, not outside of it (ibid., 94).

Is any conception of the divine more compatible with panpsychism?

I am denying that theism is implied by panpsychism. They are compatible with one another. Accepting panpsychism does not commit one to any conception of God. But certain conceptions of God fit better with panpsychist assumptions. Historically, some prominent proponents of panpsychism also endorsed views of God that may best be described as pantheistic (e.g. Baruch Spinoza and Josiah Royce) and some recent proponents of pantheism have also endorsed panpsychism, taking their commitment to both pantheism and panpsychism to be of a piece with one another (see, e.g. Leslie (Reference Leslie2001); Sprigge (Reference Sprigge2006); Pfeifer (Reference Pfeifer, Buckareff and Nagasawa2016)).

Space will not allow me to explore the connections between varieties of panpsychism and pantheism (see Buckareff (Reference Buckareff2022)). One reason for endorsing pantheism over theism is that some versions of pantheism can deliver the sort of teleology Nagel claims is needed for a tenable version of naturalism without appealing to anything outside the universe. For instance, while he does not present it as a version of pantheism, Philip Goff's (Reference Goff2019) agential cosmopsychism is arguably a version of pantheism that can explain the fine-tuning of the universe for life-permitting states of affairs to obtain. Goff's proposal is simpler than other alternatives offered to explain fine-tuning, such as multiverse theory and theism, and it does at least as much explanatory work.