Reflections on the Richard Yetter Chappell vs. Dustin Crummett Debate

I mostly side with Crummett

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I recently hosted a debate between Richard Chappell and Dustin Crummett on my YouTube channel. The two discussed two main topics: moral knowledge and psychophysical harmony. On both counts, I sided primarily with Dustin, though the debate was thoroughly interesting and enjoyable—both of these guys are some of the smartest philosophers around. Here, I’ll recap the debate and explain why I mostly agree with Dustin.

It’s somewhat surprising that I agree with Dustin. For one, it’s pretty rare that I disagree with Richard about stuff. He might be the single philosopher with whom I most agree, being a non-physicalist, moral non-naturalist, modal rationalist, and more. For another, the dispute was largely about whether theism provided a better explanation of the phenomena of moral knowledge and psychophysical harmony than atheism—and I’m an atheist. All this is to say that if I have a bias, it’s probably in the direction of Richard’s views.

A brief note: I haven’t watched the debate since it happened—my recollection of the arguments is from memory. Thus, there might be some points one of them made that I forgot. Still, I think my reconstruction will be fairly faithful.

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The first topic was psychophysical harmony. This refers to the harmonious pairing between the mental and the physical. For example, when you have the thought “I’d like my arm to go up,” your arm goes up. It could be another way. It could be that, for example, when you have that thought you instead begin to eat sushi. Similarly, it’s fortunate that our internal perception of reality tends to match reality roughly as it is. Evolution is insufficient to explain harmony because there could be radically disharmonious worlds that have the same outward behavior.

Both Richard and Dustin agreed that there is something puzzling about psychophysical harmony. Of the worlds that are physically the same as ours, the vast majority of them, including the simplest possible ones, contain radical disharmony, mental states totally out of accordance with our behavior. For example, it would be simpler for a world to be physically identical to this one but have all conscious experience be replaced by a faint experience of buzzing—a bit like hearing a bumblebee in the distance. So it’s puzzling that we live in a world where these things match up so precisely.

Richard argues that these worlds are improbable, not because of any extrinsic theoretical virtue but instead because they’re just objectively wacky. He claims that some states of affairs are just weird—and on account of their weirdness, they’re unlikely to exist. He gives the example of a world like ours but that began in 1978 where all the people have false memories of a life before 1978—even if this world was simpler than the traditional model of reality, we shouldn’t think this is the world we live in because it’s wacky. Thus, Richard claims that we can directly see that some worlds are just improbable, not in virtue of any other features other than perhaps weirdness, and that the disharmonious worlds are like that.

Dustin had two main points in response. First, he argued that objective wackiness isn’t a virtue. It sure doesn’t seem like we should discount possible states of affairs just because they seem weird to us. Furthermore, this isn’t a good explanation of why many skeptical scenarios are improbable, because many of them depend on how reality plays out. For example, Sam Altman could potentially make a lot of simulations in skeptical scenarios—the supposed objective wackiness of the scenario wouldn’t stop him. Given this, objective wackiness as a theoretical virtue can only explain why some of the skeptical scenarios are improbable—but if some other feature explains why the other skeptical scenarios are improbable then it can also potentially be used to explain why the skeptical scenarios that are objectively wacky are improbable.

Richard agreed that objective wackiness being a theoretical virtue can’t explain why many of the skeptical scenarios are unlikely. But he said that some skeptical scenarios just seem wacky—and it can rule out those on that ground. Furthermore, he argues that it is intuitive that those scenarios—like the one in which the world began in 1978—are ruled out on the basis of being objectively wacky.

This seems to give the game away in terms of Richard’s second argument. Richard had two arguments for objective wackiness being a theoretical virtue—first that it’s intuitive that it is a theoretical virtue, and second that it explains why many skeptical scenarios are improbable. But if we don’t need it to rule out most skeptical scenarios, then it seems that the second argument is defective.

As for the first argument, I don’t find it intuitive at all that wackiness is a theoretical virtue. It doesn’t seem like a theoretical virtue to me. If one theory has better explanatory power and simplicity, it seems odd to favor another theory because the first one is wacky. Furthermore, this seems to make it so that there’s no formula for calculating theoretical virtues—there’s no wackiness formula—meaning that this view is less parsimonious. In addition, this means that we need to have an infinite number of correct intuitions about which theories are likely, which is improbable on Richard’s view for reasons I’ll explain in the third section.

Richard had an argument against theism being used to explain psychophysical harmony. His argument claimed that this makes the improbability of psychophysical disharmony too contingent. When we think about scenarios that are radically disharmonious, they seem unlikely intrinsically. But if Dustin’s argument succeeds, then the most likely scenarios would be disharmonious, and conditional on atheism psychophysical harmony is likely. His argument can be phrased as follows:

1. Psychophysically disharmonious scenarios are skeptical scenarios.

2. Skeptical scenarios are intrinsically very unlikely.

3. Therefore, psychophysical harmony is intrinsically very unlikely.

4. If Dustin’s argument is correct then, assuming atheism is reasonably intrinsically probable, psychophysical harmony is not intrinsically very unlikely.

5. Atheism is reasonably intrinsically probable.

6. Therefore, Dustin’s argument is not correct.

I think this argument has some force, but it’s not super convincing. On my view, one either has reason to reject 2 or 4 or 5. There are roughly three views that one could have about skeptical scenarios:

1. Skeptical scenarios are not ruled out just because they’re skeptical. Instead, they’re ruled out for other reasons like their complexity or limited explanatory power.

If you have this view, then you should reject either 2 or 5. If you think atheism is probable then you should think that 2 is false, because atheism makes psychophysical disharmony very unlikely. If you think atheism is improbable then you should think 5 is false.

2. Skeptical scenarios should be ruled out simply because they’re skeptical. In other words, if a model of reality entails that lots of people are in skeptical scenarios, that’s a reason to think it’s unlikely.

If you think this, then you should reject 5. If you think atheism entails disharmony, and disharmony is a skeptical scenario, then you should think that atheism is unlikely. On this view, you set a constraint on theorizing that whichever theory is actual must not result in skeptical scenarios being likely. But then you’d just reject atheism on the grounds that it makes a skeptical scenario likely. This is for the same reason that the zombie-killer argument would work if it showed that dualism implies a skeptical scenario.

3. Skeptical scenarios are not intrinsically improbable. However, there is a brute requirement of rationality that an agent thinks they’re not in a skeptical scenario.

On this view, it’s not that worlds where many people are in skeptical scenarios are unlikely to exist. It’s just that you as an agent should think you’re not in a skeptical scenario. This is something that a lot of modal realists say—they admit that on modal realism lots of people like them are in skeptical scenarios, but they think that they shouldn’t think they’re in a skeptical scenario as a basic requirement of rationality. If this is true, one should reject 2 but is still justified in thinking that they’re not in a skeptical scenario.

Thus, whichever view one has about skeptical scenarios, one should reject Richard’s argument. If this is true, then Richard’s argument does not succeed. The only view Richard’s position makes sense on is if one has a hybrid view, where they think some skeptical scenarios are improbable because they’re wacky, and others are because they’re unparsimonious or lack explanatory power. But that is a very specific view that I view as the second least plausible of the four options, after 3.

Dustin also denied that psychophysical disharmony is objectively wacky. He argued that we might be accustomed to thinking it’s objectively wacky but that this is just because in the real world we only see psychophysical harmony, with very rare exceptions like drug trips and dreams. Richard argues that this can’t explain the intuition that the scenario is objectively wacky because we also don’t see philosophical zombies, but he doesn’t think those are wacky. This argument does not succeed for two reasons.

First, in the real world, lots of people don’t think zombies are conceivable. Thus, people finding scenarios different from the real world wacky is a plausible theory that explains why so many people deny the obvious conceivability of zombies. That people have a bias towards thinking the status quo is not objecively wacky doesn’t mean they’d regard all scenarios different from our own as wacky any more than the fac that people have a bias towards the status quo means they’ll regard all change to be bad.

Second, in the real world, we see lots of non-conscious things. So it isn’t hard to imagine that we’d have a non-conscious thing that acts like it’s conscious, as we see in AI, for example (obviously I’m not saying AIs are literally philosophical zombies, just that they’re sort of similar which helps explain why zombies seem possible). But a disharmonious world is far more alien and bizarre.

Furthermore, I think that there are strong reasons to think that psychophysical harmony is objectively wacky, or at the very least not the only non-wacky option. It seems like if there’s no necessary connection between two things but they line up precisely, that’s pretty wacky. For instance, it would be wacky if the number of atoms in my foot was precisely equal to the number of stars in the Milky Way. But on Richard’s view, there’s no necessary connection between our conscious states and the physical world, so it’s weird if they harmoniously line up.

Richard denies this principle, and thinks that psychophysical harmony gives a counterexample to it. But this seems ad hoc. There are no other counterexamples to the principle that I know of and the principle seems very plausible. Thus, we have strong reason to accept it.

However, even if one rejects it, there’s an even more modest principle. According to this principle, if there’s no necessary connection between two things, then it’s not the case that them not pairing up is wacky. For example, because there’s no necessary connection between the number of atoms in my foot and stars in the Milky Way, it’s not the case that them being different would be wacky. This is even more obvious but entails that disharmony isn’t wacky. One could always reject this, but it seems way more plausible to me than the conjunction of Richard’s many quite tenuous claims.

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The other point of disagreement was about moral knowledge. Dustin argues, for reasons I’ve already given and thus won’t rehash here, that the traditional account of how we acquire our moral beliefs makes no reference to the fact that they’re true. The short one sentence explanation of this is that if our beliefs are determined by physical structures in the brain, then moral facts can’t explain them, because moral facts don’t move atoms. But this is troubling—it means that, unless the brain has a special non-physical faculty of reason, then if our moral beliefs are correct, that’s pure coincidence. You don’t get out of the argument by being an anti-realist about morality, because the same thing applies to various other beliefs, like ones about which worlds are most probable, and those beliefs are needed to justify induction. Thus, the argument is as follows (they talked mostly about moral knowledge, so I will as well, but it applies more broadly):

1. If atheism is true, then the reason we believe moral claims isn’t because they’re true.

2. If the reason one has a belief is unrelated to the truth of that belief, then they’re not justified in believing it.

3. Therefore, if atheism is true, we are not justified in believing moral claims.

2 is plausible. For example, suppose that you see that your fuel tank looks all filled up. But then you notice it’s just a sticker that makes it look filled up—the thing you’re seeing is totally unconnected to how filled up the fuel tank really is. In this case, it seems like you don’t have a justification for your belief.

Richard rejects 2. He claims that you have a justified default trust in your own intuitions, even if you know that the reason you have those intuitions has nothing to do with their truth. He claims that a default trust in one’s own intuitions is the only way to avoid skepticism.

This might seem vulnerable to obvious counterexamples. For instance, suppose you think that Peru is in Africa on the grounds that it seems intuitive that it is. However, you know the only reason it seems intuitive is that you’ve been hypnotized to believe it. In this case, it seems that you should give up your belief that Peru is in Africa.

However, Richard claims that we should only trust intuitions whose explanations are unconnected to the truth of the things that they’re intuitions about if they are about necessary things. Thus, one shouldn’t trust their intuition about a contingent thing like where Peru is.

Dustin provided an apparent counterexample. Suppose that there are a lot of goblins who believe in something called The Ultimate. The Ultimate has no power in this life but lots of power in the next life. Thus, if goblins aren’t benevolent and cooperative, they’ll be punished by The Ultimate.

The goblins believe The Ultimate is necessary. However, they know that the reason they believe in it is not because it’s real—evolution would make scrappy goblins believe in a being like The Ultimate to get them to cooperate. It seems like finding this out should make them less confident in The Ultimate. Now, Richard agrees that they wouldn’t be justified in believing in the ultimate in the first place, but finding this out wouldn’t undermine their reasons for believing in the ultimate at all.

And yet it seems like there are even weirder counterexamples. Suppose I think that natural law theory is true on the basis of intuition. But then I learn that I’ve been hypnotized to have those intuitions yesterday. It seems I shouldn’t believe it. On Richard’s view, it’s unclear how my justification would be any different from people’s justification in believing ordinary moral claims on the basis of intuition.

Richard had two arguments for this view. First, he claimed that we should have default trust in our intuitions and that this is the only way to avoid skepticism. Yet this seems like a red herring. I agree we should have default trust in our intuitions. However, intuitions can have defeaters (or so it seems to me). Finding out that the reason you have some intuition has nothing to do with the truth of the thing that it’s an intuition about seems like a defeater.

Compare the situation here to the following analogy. Suppose you think that B exists because you think A caused it. If you have good arguments for this, then you’re justified in believing in B by default. But if you discover that whether or not B exists, it’s explanation has nothing to do with A, then that undercuts your justification for believing B because it’s explained by A.

Richard’s second argument appealed to an analogy. Suppose that you and a twin each took a pill. One would cause one of you to believe that 1+1=2, the other would cause one of you to believe that 1+1=3. Would you be justified, if it seems to you that 1+1=2, in believing that? It seems the answer is yes.

Here, there are three main ways to go. First, say that you wouldn’t be justified. After all, if you believe the right thing, it’s just luck—your twin believes the wrong thing for the same reason.

Second, suggest that you would be justified. One could hold both that one has justified default trust in their strongly held intuitions and that one shouldn’t trust intuitions if they know the reason they have them is unconnected to the truth of the things that they’re intuitions about. Together these just imply that one has justification for thinking that they took the right pill—for they’re justified in thinking they have the right intuitions and have them because they’re accurate.

Third, suggest that you would be justified. However, this is because you, on account of an innate rational faculty, have some innate ability to recognize justified beliefs. Just as you can see with your mind that some conclusions follow from premises, so too can you see the truth of certain premises. There actually is, on this account, a major difference between what your belief is like and what your twins is like. This view here is similar to disjunctivism about perception.

In response to this, one could suggest that the pill makes you and your twin both think the thing for the same reason—it implies a similar non-cognitive intuition. But then I think it’s obvious that it would undercut your intuition. I think you’re only justified in trusting your intuitions if you think they’re an instance of your intellect grasping the truth about their subject matter—if you have just a brute intuition that isn’t the result of correct thinking, and you know that, then it confers no justification.

Furthermore, Dustin’s argument can work without needing the claim about justification. Even if you are justified in holding beliefs on the basis of intuitions that aren’t explained by the truth of the thing that they’re intuitions about, one should still try to find the best explanation of people’s intuitions. If the reason you have an intuition that P has nothing to do with the truth of P, but P is true, and the same is true of Q, R, S, T, U, and V, each of which your intuit exist, then one should look for an explanation of why you have so many correct intuitions. Theism seems like a better explanation of this fact because God could and plausibly would want to construct us with correct moral knowledge.

In response to this point, Richard suggested that while theism might provide a slightly better explanation, there aren’t that many things that one has to have correct intuitions about. Thus, the naturalistic explanation only requires positing a few coincidences. This strikes me as clearly false. Richard and Dustin and I all agree that we’re justified in trusting our beliefs about morality, modality, and so on. So the question is merely whether these rest on many different intuitions that aren’t directly about the physical world. They do, I’ll list twenty-seven just to give you a sense, but there are far more: simplicity is a virtue, each of the nine axioms of set theory are true¹, the prime minister is not a prime number, something can’t have a color without a shape, morality would hold even in a different universe, morality supervenes on natural facts, pleasure is good, there can’t be true contradictions, all statements are either true or false, everything is itself, relationships are intrinsically valuable, inductive worlds are more likely than non-inductive worlds, creating miserable people to increase average welfare is wrong, the better than relation is transitive, modus ponens is a valid inference rule, it’s irrational to believe things with no supportive evidence and plenty of contrary evidence, the inside of relation is necessarily transitive, nothing can create itself, and there is no necessary door.

Even if we have justification for believing these, theism is a way better explanation of us getting right about all these than us just getting lucky 27 times (so is nonmechanistic rationalism, but theism is a better explanation of that being true than atheism).

Richard suggested that many of these might only be adaptive if true. But most of the things I listed don’t seem like this—if we were wrong about the better-than relation being transitive it wouldn’t seem to affect our survival.

At the end of the day, I mostly agree with Dustin on the evidence for theism. We just disagree about how to weigh up the evidence. I think probably this is all outweighed by evil, hiddenness, and the low intrinsic probability of theism. Dustin disagrees.

All in all, the debate was quite interesting and enjoyable. Any debate involving either of them is always a treat, having both was especially nice.

1. I just googled axioms of set theory and the wikipedia page had nine of them, so I might be wrong about this. Still though, there are many more mathematical axioms that we’re justified in believing.