Theism & Fine Tuning: Huemer vs. Caplan
Here, Bryan Caplan comments on Part III of my book, Knowledge, Reality, and Value: https://www.econlib.org/knowledge-reality-and-value-book-club-part-3/. The comments largely concern theism and the Fine Tuning Argument (which are discussed in my Part III, which is on metaphysics).
Background
2-minute summary of the Fine Tuning Argument: The universe has certain parameters, like the mass of a proton, or the gravitational constant, or the ratio of electric to gravitational force strengths. It turns out that a lot of these parameters have to be set to within some very narrow range of possible values in order for life to be possible. I.e., if they were a little different from what they are, there would be no living things. (E.g., because the universe would have collapsed long before life evolved, or because there would be no elements heavier than hydrogen, etc.) What explains why the universe is adjusted in just the way to permit life? Some people say: because an intelligent being created the universe, with the intention of making life possible. That's the Fine Tuning Argument.
Bryan’s Comments
“BC” indicates Bryan’s comments; “MH” is me (from the book).
1. Argument from Design
MH: Even if you’d never seen a watch before, you would immediately know that this thing had to have been designed by someone. It’s too intricately ordered to have just happened.
BC: The reason why we infer a watch-maker from a watch is not that the watch is “intricately ordered,” but that we have independent reason to believe that watches are not naturally occurring.
The “even if you’d never seen a watch before” is meant to exclude that. I.e., if you showed the watch to a person who had never seen (or heard of) a watch before, they’d still immediately know that it was an artefact. I assume that’s clear. That excludes the possibility that the conclusion is based on background knowledge about watches.
Maybe Bryan thinks they actually wouldn’t know this? Or he thinks there is some other reason for believing that watches are not naturally occurring? But I have no idea what this would be (?).
BC: Consider this rock formation: [image of Bryce Canyon]
Now compare it to this rock carving: [image of rock with heart carved in it]
The former is far more “intricately ordered” than the latter. But the latter shows design, and the former does not. Why? Because we have independent knowledge that only intelligent beings create rocks with little hearts on them.
Bryce Canyon is not really very ordered (though admittedly more ordered than just a big junk pile); you could move large parts of it around in lots of ways and not upset any salient pattern or activity. This is very unlike a watch: If you move parts of the watch around, for almost all ways of doing so, it stops working.
The rock carving has a simple order. But I don’t understand how Bryan thinks we know that it was carved by a person. I don’t know what “independent knowledge” he’s referring to. Maybe it’s the knowledge that a lot of people like heart shapes? Maybe it consists of having seen people drawing such shapes in the past?
Suppose it was a rock with a different shape on it, one that you had never seen before. Like this:
I’ve never seen that shape before I found it on the internet just now. I bet a lot of readers haven’t either. I also have not looked up what that is, or whether it is natural or man-made. This one object is my entire sample of surfaces with that shape etched into them.
Q: Can I tell whether that’s man made? Yes, I can. I have zero doubt. This doesn’t rest on background knowledge about instances of that shape.
BC: But would it not be even more implausible to think that God just appeared by chance?
Theists standardly say that God either always existed or exists “outside time” (whatever that means), and often claim that God exists necessarily. They wouldn’t say that God appeared by chance.
Btw, I didn’t address this in the book, but sometimes people say, “But isn’t God himself even more intricately ordered than living things?” No; I have no idea why people say that. Theists typically think that God is a single, simple entity. God is not supposed to have organs arranged in a body, etc., the way you do.
2. Fine Tuning
MH: [W]hy does the universe in fact have life-friendly parameters? The theist says: Because an intelligent, benevolent, and immensely powerful being set the parameters of the universe that way, in order to make life possible.
BC: I say this is an obviously terrible argument, and I don’t say such things lightly. Why? Because we have zero evidence that the anyone can “set the parameters of the universe”!
I don’t know why Bryan thinks we have no evidence of that. The theist cited the evidence: the fact that the universe has life-friendly parameters. To say that we have no evidence of anyone being able to set the parameters of the universe, you have to assume that the evidence the theist just cited is not in fact evidence of what the theist says it is evidence of. That begs the question.
I note that this type of evidence is common, and it is not in general controversial that it counts as evidence (at least when we’re talking about things other than God). I.e., the fact that a seemingly improbable phenomenon exists, and that some theory would explain that phenomenon, is standardly accepted as evidence for that theory. That is in general how we have evidence for unobserved, theoretical phenomena (atoms, magnetic fields, quarks, etc.) And you don’t have to have some other evidence for those phenomena, independent of the inference to the best explanation.
I don’t know what view of evidence Bryan is assuming or why he claims that there’s no evidence in this case, so it’s hard for me to say more.
MH: [“Made by God” example. We find a bunch of crystals that form microscopic shapes that spell out "Made by God". This results from previously-unnoticed aspects of the laws of nature.]
BC: I’d say this is excellent evidence for intelligent English-speaking life on Mars, but zero evidence for God’s existence.
Zero evidence? So the probability of God doesn’t go up at all? How can that be? God isn’t even a possible explanation of the evidence in the story? The prior probability of God existing is zero?
I deliberately designed the example to be absurdly heavy-handed evidence pointing to God (theists can only dream of finding evidence so powerful and so obvious). I didn’t think anyone would have a problem with saying that ridiculous story would count as evidence for God if it happened.
BC: After all, everything on Earth labelled “made by God” is made by garden-variety intelligent English-speaking life, so why shouldn’t we make a parallel inference on Mars?
I’ve never seen anything labelled “made by God”, so I’m not sure what things Bryan is referring to. Of course, if I saw an ordinary object, like a shirt, labelled “made by God”, I would think it was made by a human being.
This, however, was not a plausible explanation in my example, because (i) there are no people on Mars before the astronauts go there, (ii) it was stipulated that the formations are consequences of the laws of nature. Human beings do not have the ability to design the laws of nature. If there is a being with the ability to design laws of nature, I would say that being has some fairly godlike powers. I suppose it could still be incredibly advanced aliens, but I don’t know why that theory would completely overwhelm the theistic theory.
3. The Anthropic Principle
MH: [Firing squad example. You survive a firing squad, then start looking for explanations of how they all missed.]
BC: My reply: Entertaining such hypotheses only makes sense because we have independent reason to believe that people normally don’t survive fifty-man firing squads.
Again, I don’t know what independent reason Bryan is talking about. Explain it to me like I’m a baby.
I think it makes sense to entertain hypotheses for how you survived, because it is initially extremely improbable that you would survive the 50-man firing squad. Is that the independent reason Bryan is referring to? Or is that not enough, and you need some other reason? If so, I don’t know why Bryan thinks that you need some other reason.
BC: In contrast, it’s not weird for humans to exist on [a] planet hospitable to human life. And if you ask, “How did this happen?,” saying, “If the universe were very different, we wouldn’t be here [to] ask such questions” is illuminating.
I don’t understand at all why Bryan says either of those things, so I can’t respond to this other than to repeat what I said in the book.
It is weird for us to exist, once you know about the incredibly specific conditions required for us to exist. It’s weird because, well, it’s extremely improbable. Also, it’s true in the Firing Squad example that if the shooters hadn’t all missed, you wouldn’t be there to ask questions about it; yet that comment is not at all illuminating about why the shooters missed. Similarly, therefore, the statement “If the universe were very different, we wouldn’t be here to ask questions” is unilluminating about why the universe is the way it is.
BC: In any case, if you take fine tuning seriously, why can’t you just ask, “How did we happen to be in a universe where a divine being fine-tunes the laws of nature to allow our survival?”
You can ask that, but there’s nothing at all odd on its face about a conscious being deciding to create a universe that would have intelligent life.
This question strikes me as being no better motivated than the parallel question one could raise for any explanation. Someone posits X to explain evidence E. You can always say, “Why can’t you just ask, ‘How did it happen that X was the case?’” Well, sometimes you can ask that (perhaps always), but (a) this doesn’t mean that X doesn’t explain E, or that we should never make inferences to the best explanation, and (b) often X is less weird or more understandable on its face than E was.
4. Burden of Proof
BC: If X has a low prior probability of existing, and there’s no evidence of X’s existence, we should conclude that X has a very low posterior probability of existing. What gives X “a low prior probability of existing”? Many things, including (a) being very specific (e.g. X=”a guy with a feathered hat named Josephus who likes pickle-flavored ice cream and has exactly 19 hairs on his head”), and (b) being fantastical (e.g. X=Superman).
I note that Bryan is not defending the burden of proof principle as it is usually formulated, because the standard burden-of-proof principle claims that there is a burden of proof for any assertion of existence; it’s not limited to things with specially low prior probabilities (or it claims that every hypothesized entity has a low prior probability).
Anyway, I agree that the more specific the description of X is, the lower is the probability that X exists. But I’m not sure what counts as “fantastical”. In particular, I’m not sure whether the idea of a conscious being that can adjust the parameters of the universe is fantastical. If it is, then I’m not sure why we should think all “fantastical” things have a low prior probability.