Whats wrong with Pascals Wager? 1


Blaise Pascal, philosopher, scientist, mathematician and probability theorist (1623-1662), came up with a now famous reason for being a believer. It goes something like this:

  • If God exists, then the believers are quids in, they go to heaven and the non believers loose out – hence only believers win in this scenario.
  • If God does not exist, the believers get whatever they can out of life. Same for the non-believers except they don’t get the benefits/comfort that belief offers, so the believers are supposed to be slightly better off.

His final conclusion is that you are better off being a believer no matter what because thats the more rational position to take, especially when you consider the possibility of eternity on one side, its a safe bet to take. In fact, its not quite as simple as the above, but I’ll not bore you with details, knowing the above is a good enough understanding. If truly curious, then google is your friend.

Now why should we care about this? Well, apparently its still conning folks today. Take for example the philosopher Harriot Baber; she wrote an article in the Guardian a few days ago in which she explains that Pascals Wager is the reason that she embraces faith. (Click here to read her article). She should have known better, she is a philosopher after all. The tragedy here is that Pascals Wager is seriously flawed, so using it to make such a fundamental decision is crazy.

PZ (of the science-based Pharyngula blog) has a nice take-down of it (click here to read PZ’s posting). Ophelia Benson is also debating it on her blog (click here).

Now its my turn, so what is wrong with Pascals wager?

  • First of all, it assumes you have a choice about belief. Can you choose to believe that fairies really exist? OK, lets add a bit of motivation. If offered $10,000 would you be prepared to believe in fairies? You could of course fake it, but then the fairies would know.
  • Which belief is correct? Pascals wager only assumes one valid system of belief, Catholic Christianity. But what if its not the right one, what if the correct belief is Islam, or Hinduism or one of the many other belief systems? In that instance, picking Christianity would be the wrong bet. Given the huge number of different beliefs, its obviously not a simple choice between non-belief and belief, but a very complicated choice between non-belief and a vast assortment of beliefs. Given that there is such a diverse choice, there is a very high probability that you might pick the wrong one, so its not a safe bet at all.
  • Decision theory (the basis for Pascals wager) is fine and sound until you introduce eternity (infinity). Once you add infinity into the mix, decision theory breaks down. With infinity choices becomes meaningless and any course of action is as good as any other (Infinity + 1 = Infinity, therefore 1 is totally irrelevant). You can use this trick (as Pascal does) to make a case for almost anything. I’m not accusing pascal of deliberate fraud, he simply managed to fool both himself and any others who embraced the same flawed decision theory instance.

In the end, truth is truth, regardless of what people believe or want to believe, using decision theory (with or without a flaw) to make a bet is not an appropriate strategy for discerning truth. It fact, all you are doing is saying, “truth and reality be dammed, I’ll just make a safe bet”. Not sure about that? OK try this, “Dam the evidence or truth, lets simply lock-up all accused of a crime to be sure we get the guilty ones”. Not acceptable? Of course not, so why accept it for a belief decision, yet reject it for other decisions?

We should instead strive to use evidence to decide what is truth, and not play silly games with infinity that end up leaving us tied up in psychological knots.

When faced with extraordinary claims, you need extraordinary proof, not mind games. Remember, be skeptical.


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