A compositional fine-tuning argument

Assume naturalism about the human mind. Our best naturalistic account of the human mind is functionalism. But functionalism faces multiple too-many-minds problems. The most famous of these are the Chinese Room and its variants like Schwitzgebel’s consciousness of the United States argument. But a more troubling bevy of problems comes from abundant ontologies. Thus, as Dean Zimmerman noted (building on Unger), where I am there are many clouds of atoms that differ from me in an insignificant way—say, an atom in some insignificant skin cell. On functionalism, each of these clouds should have the same conscious states as I do. Or, as Johnston argued, I have many personites—temporal parts of my life that are intrinsically just like the life of a person could be. On functionalism, they will have the same conscious states as me. The clouds of atoms and personites are not just a consequence of functionalism but also of other naturalistic accounts of mind.

But why are the too-many-minds problems problems, beyond the fact that they are counterintuitive? After all, we have good reason to think that the mind is mysterious enough that the true theory will have some counterintuitive consequences.

I think the best answer is ethics. If a country has a person-level mind, then it would be a murder-suicide for the citizens to vote to dissolve the country. But it is not wrong for the citizens to vote to dissolve a country for, say, economic reasons. If the Zimmerman argument is right, then where there is a person feeling pain, there are many other beings with human-level consciousness feeling the same pain. But the number of being that coincide with a specific person rapidly increases with the size of the person—the more cells they have, the more clouds of atoms there are that differ with respect to a few insignificant atoms. Consequently, if we have a choice between relieving an equal pain in two smaller persons or one much larger person, we should always relieve the pain in the larger one, because the number of conscious atom clouds coinciding with the larger person is likely much larger than the total number of atom clouds coinciding with the smaller ones. In other words, crucial intuitions about equal treatment of people are undercut. Something similar is true on the Johnston arguments if the number of personites is finite, and if it’s infinite we have other ethical problems. On the other hand, there is no immediate serious ethical problem in saying the Chinese Room is conscious.

Given functionalism, I think there is only one way to block the ethically problematic too-many-minds cases: deny that the alleged entities exist. There are no countries. There is only one human-shaped cloud of atoms where I am. There are no personites. But we better not go all the way to blocking all complex objects—we will get other ethical problems if we conclude with the early Unger that humans don’t exist. In other words:

1. If functionalism and ethical realism are true, restricted composition is true.

Restricted composition says that some but not all (proper) pluralities of atoms compose a whole. Note that (1) also applies to some other naturalistic theories than functionalism.

But it’s not enough that restricted composition be true. What we need is a carefully fine-tuned restricted composition. If we restrict composition too much, there will be no humans—and that’s ethically unacceptable. If we don’t restrict composition enough, there will be too many minds of an ethically problematic sort. In other words, restricted composition must be fine-tuned to fit with human ethics.

That’s difficult to do. For instance, van Inwagen’s life-account—that a plurality composes a whole if and only if it has a life together—has the problem that clouds of atoms that differ from me insignificantly have a life together just as I do.

Given naturalism, I think any restricted composition account that fits with ethics will involve seemingly arbitrary choices. Thus, one might start with van Inwagen’s account, but have an incredibly fine-grained account of what counts as “a life together” such that only one of the clouds of atoms nearly coinciding with me has a life together—namely, the cloud constituting me. But such a fine-grained account will have a ton of free parameters, and will be an implausible candidate for a metaphysically necessary account of restricted composition. Thus, the account will not only be fine-tuned but will likely be contingent.

How do we explain the fine-tuning of restricted composition for ethics? It’s hard to see how to do it other than by supposing that fundamental reality is value-driven. There are two main value-driven theories of fundamental reality: theism and axiarchism, where the latter is something like the view that reality must be for the best. Thus we have an argument for theism or axiarchism. And axiarchism, as Rescher noted, plausibly implies theism, since it’s for the best that there be a perfect being. So, either way, we get theism.

We can also run this argument in a Bayesian way. Assume naturalism about the earth ecosystem as a background belief, and assume as part of the background that the physical simples are arranged as they are. On atheism, it is extremely unlikely that composition is fine-tuned for ethics. On theism, it is at least moderately likely. So, we have significant evidence for theism.

Objection: God can’t control which cloud of atoms composes a whole, because whatever is the answer, the answer is metaphysically necessary.

Response: First, as noted above, it is likely that any ethically fine-tuned restricted composition theory has a bunch of parameters that appear contingent, and hence is likely contigent. Second, God is creator and has power over being itself. It seems quite plausible that where there is a bunch of particles God can lend his power to create an entity composed of the particles. Third, if God exists, likely modality itself is grounded in God—all reality necessarily reflects the goodness of God. But if so, then divine goodness may help to explain surprisingly good features of necessary truths, such as a fine-tuned but necessary theory of composition. Fourth, we don’t need to be certain of any of the above. All we need is that one of these stories is an order of magnitude more likely on theism than the fine-tuning of restricted composition is given naturalism (where the probabilities are all epistemic).

If my argument succeeds, it yields a dilemma:

2. Either naturalism about humans is false or God exists.

One may ask whether some variant of the above fine-tuning argument applies if naturalism about humans is true. I expect it does, but the exact shape of the bump under the rug will be different for different non-naturalistic stories. For instance, on Cartesian theories, there will be the question of why there is exactly one soul per human body. On strong emergence, we can ask why consciousness arises in exactly one of the human-shaped clouds of atoms where I am.

Restricted composition and laws of nature

Ted Sider famously argues for the universality of composition on the grounds that:

1. If composition is not universal, then one can find a continuous series of cases from a case of no composition to a case of composition.

2. Given such a continuous series, there won’t be any abrupt cut-off in composition.

3. But composition is never vague, so there would have to be an abrupt cut-off.

Consider this argument that every velocity is an escape velocity:

4. If it’s not the case that every velocity is an escape velocity from a spherically symmetric body of some fixed size and mass, then one can find a continuous series of cases from a case of insufficiency to escape to a case of sufficiency to escape.

5. Given such a continuous series, there won’t be any abrupt cut-off in escape velocity.

6. But escape velocity is never vague, so there would have to be an abrupt cut-off.

It’s obvious that we should deny (5). There is an abrupt cut-off in escape velocity, and there is a precise formula for what it is: (2GM/r)^1/2 where G is the gravitational constant, M is the mass of the spherical body, and r is its radius. As the velocity of a projectile gets closer and closer to the (2GM/r)^1/2, the projectile goes further and further before turning back. When the velocity reaches (2GM/r)^1/2, the projectile goes out forever. There is no paradox here.

Why think that composition is different from escape velocity? Why not think that just as the laws of nature precisely specify when the projectile can escape gravity, they also precisely specify when a bunch of objects compose a whole?

My suspicion is that the reason for thinking the two are different is thinking that composition is something like a “logical” or maybe “metaphysical” matter, while escape is a “causal” matter. Now, universalists like David Lewis do tend to think that the whole is a free lunch, nothing but the “sum of the parts”, in which case it makes sense to think that composition is not something for the laws of nature to specify. But if we are not universalists, then it seems to me that it is very natural to think of composition in a causal way: when a proper plurality of xs are arranged a certain way, they cause the existence of a new entity y that stands in a composed-by relation to the xs, just as when a projectile has a certain velocity, that causes the projectile to escape to infinity.

Some may be bothered by the fact that laws of nature are often taken to be contingent, and so there would be a world with the same parts as ours but different wholes. That would bother one if one thinks that wholes are a free lunch. But if we take wholes seriously, it should no more bother us than a world where particles behave the same way up to time t₁, and then behave differently after t₁ because the laws are different.

Humeans have good reason to reject the above view, though. If the laws of composition are to match our intuitions about composition, they are likely to be extremely complex, and perhaps too complex to be part of the best system defining the laws on a Humean account of laws. But if we are not Humeans about laws, and think the simplicity of laws is merely an epistemic virtue, the explanatory power of laws of composition might make it reasonable to accept very complex such laws.

That said, we all have reject the simple causal version of the above view, where a proper plurality composing a whole causes the whole’s existence. For instance, I am composed by a plurality of parts that includes my hair, but my hair is not a cause of my existence: I would have just as much existed had I never developed hair. So a more complex version of the causal view is needed: initial parts (maybe the DNA in the zygote that I started as) causally contribute to the existence of the whole, but the causal relation runs in a different direction with respect to later parts, like teeth: perhaps I and my teeth together cause the teeth to be parts of me.

(I don’t endorse the more complex causal view either. I prefer, but still do not endorse, an Aristotelian alternative: when y is in a certain condition, it causes the existence of all of the parts. This is much neater because the causation always runs in the same direction.)