Pascal’s Wager for Climate Denialist by Hemmo Laiho

TIAS Post-doctoral researcher Hemmo Laiho

Blaise Pascal (1623–1662), a famous French mathematician, is also famous for a philosophical slash theological slash game-theoretical thought experiment known as Pascal’s wager. You can find the thought experiment in the section §233 of the collection of his notes titled as Thoughts (Pensées, originally published 1670) and from many secondary sources. Skipping details and nuances and already adapting the original version for my purposes, the experiment goes roughly as follows.

You cannot prove by reasoning whether God exists or not, but you can legitimately think what consequences there would be if you believed in God and acted accordingly or if you did not. You can also speculate about the gravity of these consequences in two opposing scenarios, in one of which there is God and in the other of which there is no God. You end up facing four options and possible results: (1) If you are a true believer and God exists, it can be expected or at least supposed that your gain is enormous or indeed infinite (eternal rejoice, you know). (2) If you are an unbeliever and God exists, then you risk infinite gain, possibly facing infinite loss (perhaps you are not allowed in Heaven). (3) If, on the other hand, you believe in God but God does not exist, it can be supposed that you end up limiting your choices in this life, whereas (4) as an unbeliever you would gain more. Such mundane things, however, are disproportionate to infinitely good and infinitely bad, which is why it is rational for you to opt for the first alternative, that is, to believe in God and act accordingly.

Let’s examine the argument closer. Pascal does not deny that you may perfectly well believe one way or the other. What he suggests is that you should choose to believe in God, since that has the best possible consequences, assuming God in fact exists, and not too weighty costs if it turns out that God does not exist. He has been criticized for this because you may question if anyone can choose to have faith. More importantly for my purposes, however, Pascal claims that it is beyond our reason to affirm the existence or non-existence of God, and I think he has a point here: how both theism and atheism are irrational positions in the sense that their truth cannot be decided by mere reasoning. In this regard, the only rational position to take is to remain agnostic in such matters. Pascal, however, seems to find it difficult to accept that one could remain neutral about God’s existence. So, wager you must.

Whether or not Pascal does this for presentational purposes does not matter. Again, he has a deeper point in mind. It has to be the case that God either exists or does not exist. This much we can perfectly know by reasoning, and it follows from this reasoning that it might be the case that God exists, no matter how uncertain that is, and this totally regardless of your own belief or disbelief in God. This is to say that there is probability involved, even if no one can provide the odds, and to simply disregard a genuine possibility would be either sheer ignorance or some sort of epistemic nihilism, whereas denying or affirming God’s existence beforehand would be dogmatism. Add to this the set of possibly very drastic consequences of adopting a certain stance and you would be fool not to gamble and place your bet in the way Pascal’s argument implies. The risk would just be too big. Thus, what seemed first as irrational choice between two undecidable positions, appears as rational in the end, and not because you can decide by reasoning whether God exists or not, but because you can decide by reasoning whether it would make better sense to adopt one set of beliefs instead of another and guide your actions accordingly.

Whatever one thinks of the religious aspects of the original version of Pascal’s wager, or even finds it blatantly silly in this respect, the thought experiment itself can be used as a test platform for rational thinking in a more general way, which might have been Pascal’s intent as well. This is to say that the formal structure of the argument can be detached from the original example and applied to very different kinds of cases. One such case is climate change.

Suppose you have a friend, Jim, who denies the existence of climate change in either of the following ways. It might be the case that Jim does not accept the reality of this phenomenon at all. Alternatively, Jim might refuse to accept that climate change is dependent on human action. Maybe he thinks that even if there was such a planetary process going on, there is nothing we can do about it.

Let’s examine the way Jim thinks. If Jim refuses to even ponder the possibility of climate change and whatever might follow from that, Jim is dogmatic in his thinking—he behaves epistemically just like someone who in the original scenario affirmed or denied God’s existence beforehand. Affirming climate change but denying that it is a human-originated process, the ill consequences of which might be diminishable by changing human behavior, may seem more reasonable, but that too makes Jim dogmatic assuming he simply skips such a possibility and jumps to his conclusion. Though Jim is free to be a dogmatic if he so chooses, according to above analysis such a position is not only an epistemic non-starter but makes Jim’s thinking irrational. This in turn means that Jim’s stance on the matter is not genuinely epistemic at all but an article of faith. If so, the next time Jim talks about climate change you should be aware that his views are in this respect formally no different from those of a religious fundamentalist. Add to this Jim’s ignorance of the possibility, however slight, that if we took climate change seriously enough, we might be able to improve planetary life conditions for our children and other beings, and Jim ends up being a bloody nihilist too.

Let’s assume instead that Jim is a rational person who also cares about the future. This being the case, though Jim is more inclined to think that climate change does not exist or takes place independently of human action, he too realizes that he is not in a position to refute its existence and the possibility of human intervention from the outset. If so, the possible scenarios can be limited to the following four. (1) People generally believe in climate change and act accordingly. If climate change exists, it can be expected that considerable future losses can be avoided. In Jim’s case, this means that Jim is wrong but gains much nevertheless. (2) People generally do not believe in climate change and act accordingly. If climate change exists, considerable unavoidable losses are to be expected. Jim is not only wrong but nobody gains anything in the long run. (3) People generally believe in climate change and act accordingly. If climate change does not exist, some minor losses, like those related to “fly guilt”, are to be expected. For Jim personally, there would be some petty gain as he gets to say: “I knew it!” (4) People do not generally believe in climate change and act accordingly. If climate change does not exist, no big avoidable losses are to be expected. Nobody, including Jim, needs to have a bad conscience.

Put like this, we have some interesting similarities and differences with respect to the original example. The biggest similarity is that the gainless second scenario is the worst-case scenario, while the first one seems to be the most rational choice, and not just because of the grand-scale risks involved, but because the lesser gains of the third and fourth scenarios are nothing in comparison to the possible gains or avoidable losses of the first scenario. The biggest difference to the original wager is that there is no infinitely good this time (contrary to what Belinda Carlisle sang, Heaven is not a place on earth). Also, the climate change scenario is explicitly collective: what really counts is the human action at large. Most importantly, even if the best possible scenario was not optimal, and indeed, even if it was not very likely, it makes sense to adopt it instead of the alternatives and act accordingly. Add to that the following two things and choosing the first option begins to look even more reasonable.

Firstly, even if climate change as such did not exist or was utterly unavoidable, acting as if it did would presumably have good consequences anyway—think of waste reduction, for example. Jim should thus consider changing his environmental behavior in any case. Secondly, the existence of climate change and its connection to human activities and emissions, some bad effects of which are probably possible to reduce or even nullify, is strongly supported by vast scientific body of evidence that has accumulated for several decades. Not only does this make the two wagers very different—one having more to do with hereafter, the other having everything to do with the real world—but adds another likelihood to the picture: even though science is not perfect and there are contradictory pieces of evidence and interpretations of data, Jim should bet on the weightiest opponent and start to act accordingly, and not because scientific inquiry deals in absolute certainties, but because it indeed does not and nevertheless is the best we have got.

EPILOGUE: Rational thinking and harnessing it to the improvement of humankind was one of the leading ideas of Enlightenment, a wide socio-politico-philosophical enterprise that kicked off in the century after Pascal’s death. Climate change is just one of the things that shows how the same idea is particularly topical today, which is why we planned to discuss it further in a TIAS symposium on Enlightenment, which was to be held at the University of Turku in April 23, 2020, but then postponed due to the corona outbreak — another test case for a Pascalian wager.

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