Saturday, June 17, 2023

Flipping Pascal's Wager on Its Head

In his famous Wager, Pascal contemplates whether one should choose to believe in God. (Maybe we can't directly choose to believe in God any more than we can simply choose to believe that the Sun is purple; but we can choose to expose ourselves to conditions, such as regular association with devoted theists, that are likely to eventually lead us to believe in God.) Although there's some debate about how exactly Pascal conceptualizes the decision, one interpretation is this:

  • Choose to believe: If God exists, infinite reward; if God does not exist status quo.
  • Choose to not to believe: If God exists, infinite punishment; if God does not exist status quo.
  • Suppose that your antecedent credence that God exists is some probability p strictly between 0 and 1. Employing standard decision theory, the expected payoff of believing is p * ∞ [the expected payoff if God does exist] + (1-p) * 0 [the expected payoff if God does not exist] = ∞. The payoff of not believing is p * -∞ + (1-p) * 0 = ∞. Since ∞ > -∞ (to put it mildly), belief is the rational choice.

    Now maybe it's cheating to appeal to infinitude. Is Heaven literally infinitely good? (There might, for example, be diminishing returns on joyful experiences over time.) And maybe decision theory in general breaks down when infinitudes are involved (see my recent discussion here). But finite values also work. As long as the "status quo" value is the same in both conditions (or better in the belief condition than the non-belief condition), the calculus still yields a positive result for belief.

    If not believing is better in the absence of God, it's a bit more complicated. (Non-belief might be better in the absence of God if believing truths is intrinsically better than believing untruths or if believing that God exists leads one to make sacrifices one wouldn't otherwise make.) But if Heaven would be as good as advertised, even a smidgen of a suspicion that God exists favors belief. For example, if life without belief is one unit better than life with belief, contingent on the non-existence of God, and if Heaven is a billion times better than that one-unit difference and Hell a billion times worse, then the expected payoff for believing in God is p * 1,000,000,000 + (1-p) * -1, and the expected payoff of not believing is p * -1,000,000,000 + (1-p) * 0. This makes belief preferable as long as you think the chance of God's existing is greater than about one in two billion.

    So far, so Pascalian. But there's God and then there's the gods. It seems that a more reasonable approach to the wager would consider theistic possibilities other than Pascal's God. Maybe God is an adolescent gamer running Earth in a giant simulation. Maybe the universalists are correct and a benevolent God just lets everyone into Heaven. Or maybe a jealous sectarian God condemns everyone to Hell for failing to believe the one correct theological package (different from Pascal's).

    If so, then the decision matrix looks something like this [click to enlarge and clarify]:

    In other words, quite an un-Pascalian mess! If the positive and negative values are infinite, then we're stuck adding ∞ and -∞ in our outcomes, normally a mathematically undefined result. If the values are finite but large, then the outcome will depend on the particular probabilities and payoffs, which might be sensitive to hard-to-estimate facts about the total finite goodness of Heaven or badness of Hell. And of course even the decision matrix above is highly simplified compared to the range of diverse theistic possibilities.

    But let me suggest one way of clarifying the decision. If God is not benevolent, all bets are off. Who knows what, if anything, an unbenevolent God might reward or punish? Little evidence on Earth points toward one vs another strategy for attaining a good afterlife under a hypothetical unbenevolent deity. I propose that we simplify by removing this possibility from our decision-theoretical calculus, instead considering the decision space on the assumption that if God exists God is benevolent. Doing that, we can get some decision-theoretic traction: a benevolent God, if he/she/it/they reward anything, should reward what's good.

    This, then gives us mortals some (additional) reason to do whatever is good.

    Here's something that's good: apportioning one's beliefs to the evidence. The world is better off, generally speaking, if people's credence that it will rain on Tuesday tends to match the extent of the evidence that it will rain on Tuesday. The world is better off, generally speaking, if people come to believe that cigarette smoking is bad for one's health once the evidence shows that, if people come to believe in anthropogenic climate change once the evidence shows that, if people decline to believe in alien abductions given that the evidence suggests against it, and so on. Apportioning our beliefs to the evidence is both a type of intellectual success that manifests the flourishing of our reasoning and a pragmatic path to the successful execution of our plans.

    This is true for religious belief as well. Irrationally high credence in some locally popular version of God doesn't improve the world, but in fact has historically been a major source of conflict and suffering. Humanity would be better off without a tendency toward epistemically unjustified religious dogmatism. Nor should a benevolent God care much about being worshipped or believed in; that's mere vanity. A truly benevolent God, with our interests at heart, should care mainly that we do what is good -- and this, I suggest includes apportioning our religious beliefs to the evidence.

    The evidence does not suggest that we should believe in the existence of God. (We could get into why, but that's a big topic! We can start by considering religious disagreement and the problem of evil.) If a benevolent God rewards or at least does not punish those who apportion their belief to tge evidence, a benevolent God should reward or at least not punish non-believers.

    If God does not exist, we're better off apportioning our (non)belief to the (non)evidence. If a benevolent God exists, we're still better off not believing in the God. If God exists but is not benevolent, then decision-making policies break. Thus, we can flip Pascal's wager on its head: Unless we reject decision theory entirely as a means to evaluate the case, we're better off not believing than believing.

    18 comments:

    Brandon said...

    It's a side point, and a common confusion, but Pascal's Wager doesn't include hell or infinite punishment. Infinite punishment arises in a distinct branch beginning with the Port-Royal Logic which, because it happened to be published first, had more influence for quite a while.

    A more serious issue is that Pascal isn't contemplating whether we should choose to believe in God; he is arguing against a position that one should suspend judgment because there is no evidence at all either way, by showing that we can have practical reasons even if we assume there is no evidence. The Wager is found broken up across different fragments, but in at least one he is explicitly responding to an agnostic argument that Christians are irrational for not suspending judgment. Pascal himself thinks there is evidence for Christianity, but in the Wager he is arguing on his opponent's assumption. (This is also why the other-deities objection doesn't work against Pascal himself; he's not putting forward the Wager because he thinks this is the best way to think about the matter, but is instead replying to specific kinds of arguments against Christianity in particular that were put forward by fashionable skeptics in France, turning their enthusiasm for gambling against them. The reason he is doing that is that this is all for an intended-but-never-finished book on the evidence in favor of Christianity and he first needs to deal with the fact that many of his potential readers would dismiss out of hand anything he might say on the subject. )

    I always find talk of 'apportioning belief to evidence' interesting, because nobody ever says what unit of measurement belief and evidence have in common or what methods of measurement they think should be used to do check the apportioning.

    Paul D. Van Pelt said...

    A couple of thoughts here. When I first encountered the wager, I found it disingenuous. That did not come from a deeply devout theist, because, even then I was not one. The face value of it, for me, was he was hedging his bet, treating the proposition as one might a thought experiment or something like that. Insofar as faith is not fool proof, nor are the faithful all fools, Blaise may have believed or sought to believe he could have it both ways...not damned in either direction of fit, as Searle might have had it. But this does not work. If we assume God exists and sits in His cloud of infinite wisdom, then we know HE is not going to have it both ways and also sees the disingenuousness of the wager, a priori. Pascal should have known this when dreamed the whole thing up. And, he probably did. Which begs a question: was the wager nothing more than an idle joke? Or even: was the jokester merely bored, that day? I guess both versions are fundamentally the same.

    Anonymous said...

    Interesting points, everyone.

    Mike and Paul: I think you're pointing out that belief based on a wager may not be genuine. From what I read of Pascal, I think he was a voluntarist who believed that if you accepted the wager, you could then take actions to start gradually getting genuine belief. Of course, plenty of people, including me, would question whether that is possible. But even if it doesn't work, I don't think that means Pascal was joking, Paul, but more likely had just made a mistake.

    Brandon: The Stanford Encyclopedia of Philosophy does claim Pascal himself mentioned "hell" in this context at some point, at least, but I'm not a scholar so I can't be sure. It does mention that there is debate on whether the negative utility is finite or infinite, though I think that may not matter too much as long as we assume that infinite positive utility is also an option. As for the other-gods issue, I've also heard that Pascal and possibly his intended audience believed that all options except for Christianity and atheism could be rationally ruled out in other ways (which may not be contradictory with your explanation). Of course, that idea is more doubted today even in the West. As for belief and evidence, I'm wondering whether some people (though maybe not all) are using it in the context of Bayes' Theorem? I believe in that case, the common unit of measurement would be probability. I can't think of anything else related immediately, though there might be.

    Paul D. Van Pelt said...

    Eric:
    Your points are well-received, considered and taken. I respond in this way: disingenuine is a not-often used term. It does not mean lacking authenticity or sincerity in the same sense as those terms. Rather, it more accurately connotes deception that is intentional---which, of course, is why we call it deception, in the first place. Think of twenty-first century politics, thus far. No, I don't think Pascal was making, or did make, a mistake. He was far too clever for anything so pedestrian. I am wrong a lot. It is called philosophy because, in most ways, it lacks the precision necessary for pursuit of physics, math and/or science. None of those disciplines rely as heavily on rhetoric. The Stanford philosophy blog interested me, in and around 2012. But the commentary there got too rhetorical for me.

    If you don't think Pascal could have been joking, that is your prerogative. I was not there, so, I don't know.

    Anonymous said...

    Paul: Are you talking to the anonymous commenter above? If so, I just need to clarify to anyone reading that it's me, and I'm not Eric himself, but an anonymous reader of the blog who doesn't feel comfortable publicly revealing their identity on the Internet at the moment.

    As for whether Pascal made a mistake or not, I don't think being "clever" makes you immune to making mistakes, even big ones. I'm not a theist myself and I think theism (or at least its most common forms) is worthy of a lot of criticism, but I think the specific argument that theists are stupid isn't a good one (although the argument that all theists are affected by cognitive biases present to some degree in all humans may be better). This especially applies to the intellectuals of the past who lived in societies where religion was more pervasive than it is today, and who did not have much of the scientific knowledge that we now have.

    Again: I think Pascal's Wager is flawed and I'm not trying to defend it, and I do technically agree that there is a nonzero probability that Pascal was joking. I just don't think the probability is as high as you seem to think it is. Ultimately, though, Pascal's motivations may not be that important, but I do think that arguments against theism, especially from people who say they support truth and rationality, should be based on facts and be as reasonable as possible.

    Paul D. Van Pelt said...

    To the anonymous person who replied to my comment, directed to Eric: yes, the comment was directed to Eric. That should have been clear enough, insofar as I prefaced it with
    Eric:

    Anonymous: your comment is also noted.

    Eric Schwitzgebel said...

    Thanks for the comments, everyone!

    Mike: Thanks for the cool Locke quote.

    Brandon: It has been decades since I read the entire Pensees. I make no claims at Pascal interpretation here. I think the wager idea is interesting in several of the various forms it has taken. On apportioning belief to evidence: I'm not sure what you mean that no one ever talks about units and methods of measurement. Formal epistemology is basically all about this, on my reading. But also there's just the commonsensical idea that one should strongly believe what one has strong evidence for, weakly believe what one has weak evidence for, etc., along with ordinary ideas about the relative evidential strength of various types of observation, testimony, etc.

    Anon & Paul: I guess I'm with Anon on this one. Pascal's wager has argumentative merit, and my (long ago) recollection of the context of the Pensees is not one in which Pascal is a jokester about religious issues. As I briefly gesture at in the post, even if direct voluntarism isn't plausible, indirect voluntarism is at least somewhat plausible: One can voluntarily put oneself in a circumstances that are likely to (involuntarily) produce belief.

    Paul D. Van Pelt said...

    All good. I have often bucked mainstream thought. I will often do so. No worries, here. Like this blog a lot---that will not change.

    Paul D. Van Pelt said...
    This comment has been removed by a blog administrator.
    Brandon said...

    Eric,

    Formal epistemology is all about logical structures; it is epistemology, not metrology. It tells us nothing at all about how to measure anything -- arguably, that's why it's called 'formal', the fact that it abstracts from such things.

    It's also not a commonsensical idea that there are strengths of belief and evidence that go in lockstep with each other. Why would one make such an association? As far as I can tell, most people just think you should believe things on strong evidence, and if you have weak evidence, you might believe or not; beyond that, they don't have any assumption of co-varying intensities, or at least, they don't make such assumptions in practice in everday life -- people regularly believe things on things they think are weak evidence, and regularly doubt even in the face of things they think are strong evidence. Philosophers have tended to accept such ideas because they read early modern empiricists; but the early modern empiricists held such things on the basis of very controversial empiricist theses, not on the basis of common sense. And the empiricists never actually had a way to measure these things either; after proposing reductions of evidence to psychological qualities, they mostly just appealed to direct introspection for both belief and evidence. Why would one think one can measure the strength of one's beliefs by introspection, much less the strength of evidence? But if not by introspection, what else is there that gets these results (e.g., what else could be supporting this supposed common sense)? It always tends to get handwaved.

    Arnold said...
    This comment has been removed by the author.
    Chris Stephens said...

    If I recall, Mougin and Sober ("Betting Against Pascal's wager") also consider the "theology" whereby God rewards all and only those who believe on the basis of evidence...

    On the other hand, I think it is only "roughly" (or "as a rule", perhaps) true that we're better off believing on the basis of the evidence. This is surely a big empirical claim. There are lots of prima facie counterexamples (see eg., William James, etc.)

    Paul D. Van Pelt said...

    I tried to delete my last comment from Monday, June 19. No success with that. Please ignore it. Thanks!

    Arnold said...

    Paul click on the comment you want deleted...
    .click on post a comment...
    ..click on icon after PDT...
    ...click on delete...
    ....and sin no more...

    Paul D. Van Pelt said...

    Thanks, Arnold (or, Arnie). No sins intended. This is a philosophy blog, right? On these platforms, it is not always entirely clear: even those schooled in one depth, venture into others. Interdisciplinarianism is rampant now. 'Nuff said.

    Howard said...

    I'm a non believing Jew.
    G-d probably won't punish me for not believing in him, at least not infinitely.
    If I do believe in him and devote myself to what is called Orthodox Judaism, I have to put on tfillin and eat kosher and seclude myself to relations with Jewish women, among other things.
    If I believe in him and he exists, then I might go to heaven and might cease to exist anyway
    A point about your calculus: it is not just the outcome in the four squares that matters; it's the psychological impact.
    If I think I'm going to cease to exist forever, that causes Kierkegaardian levels of dread; if I think I"ll live forever, the reawrds are in this lifetime

    Paul D. Van Pelt said...

    Thank YOU Howard. The wisdom shines through and the sensitivity is refreshing. No,I am not from the 'awesome' generation. More like William James. But even he was born before my Grandfathers and Grandmothers.

    Eric Schwitzgebel said...

    Thanks for the continuing discussion, folks!

    Paul: I went ahead and deleted your Monday comment, since you appear to want that. (Let me know if you want it reinstated.)

    Brandon: Another way to measure strength of belief is by what one will wager (in a broad sense of wager) or more broadly what risks one will take. And here it does seem like there's a general tendency to apportion by evidence. With definitely some exceptions, if there's weak evidence that X is safe I'll be less likely to risk X than if there's strong evidence that X is safe.

    Chris: Thanks for the reference, and yes I agree that it's only a rough rule, including for Jamesian reasons.

    Howard: Yes, I agree that the psychological impact matters.