Monday, May 14, 2012

An Economic Assault on Pascal's Wager as an Example of Skewness

I've recently heard a few people discussing the merits of Pascal's Wager on multiple podcasts, including my favourite call-in atheism podcast "The Atheist Experience". Pascal's wager is essentially a 2x2 game theory grid in which there are two choices (believe in god or don't believe in god) and there are two outcomes (there is a god and there isn't a god) with the equilibrium decision being that you should believe in god because it not only offers the greatest possible prize (heaven) but also offers a safer result in the case that you are wrong (a moral life vs hell). The following is from the Wikipedia page:


1. "God is, or He is not"
2. A Game is being played... where heads or tails will turn up.
3. According to reason, you can defend neither of the propositions.
4. You must wager. (It's not optional.)
5. Let us weigh the gain and the loss in wagering that God is. Let us estimate these two chances. If you gain, you gain all; if you lose, you lose nothing.
6. Wager, then, without hesitation that He is. (...) There is here an infinity of an infinitely happy life to gain, a chance of gain against a finite number of chances of loss, and what you stake is finite. And so our proposition is of infinite force, when there is the finite to stake in a game where there are equal risks of gain and of loss, and the infinite to gain.

Choice God exists (G) God does not exist (~G)
Belief (B) +∞ (heaven) +1 (moral benefits)
Disbelief (~B) −∞ (hell) -1 (immoral consequences)

Now one thing I haven't seen is someone make an argument based on the economic principal of "skewness" against Pascal's Wager. Skewness is the idea that people are willing to risk something small for an exceptionally small chance at a very large reward. The most common examples are lotteries; people risk a couple of dollars for a small chance to win millions. When you calculate the odds of winning the jackpot it becomes painfully clear that the present value of your two dollar investment is nearly zero; that is to say that the odds of winning the jackpot are so slim that even though the wager is low and the maximum potential is high the risk involved (odds of winning) are so low that the jackpot divided by the likelihood of winning is nearly zero.
A simple demonstration would be this:
Ticket price: $2
Jackpot: $15,000,000
Odds: 1/100,000,000
Ignoring the complication of calculating how many tickets were sold and discounting the jackpot based on the odds that there are going to be more than one winning ticket (which actually makes the lottery even worse) you see that
$15,000,000/100,000,000= $0.15 or that your two dollar ticket is really only worth fifteen cents and your best option when it comes to the lottery is to not play.

So how does this relate to Pascal's Wager? Well it requires us to look at his supposed payouts one more time the issues should be clear:

Choice God exists (G) God does not exist (~G)
Belief (B) +∞ (heaven) +1 (moral benefits)
Disbelief (~B) −∞ (hell) -1 (immoral consequences)

It is probably fair to note that the benefits/costs of heaven/hell if there is a god is probably correct. Where the trouble lies in what he supposes are the costs and benefits to different decisions if the result is there is no god. If there is no god then why would the belief in a god and its moral code be a net benefit? Belief in god causes people to do all sorts of horrible things. These range from war and terrorism, subjugating women, disrespecting the environment and refusing to give gay people equal rights to wasting money on tithes, being unable to enjoy life because the way you were born conflicts with church teachings, potential psychological trauma caused by ignoring the biological urge to have sex well past puberty and wasting time studying incorrect science.
Likewise, disbelieving in god if there is no god, is very much a positive. It isn't immoral as Pascal says but rather an affirmation of freedom. When one accepts that he or she on average has less than 80 years on this planet life becomes precious. You appreciate everything, work toward freedom for everyone and aiding the environment because ultimately the only thing you have even close to immortality is your legacy. So in that way I would adjust the chart as follows:

Choice God exists (G) God does not exist (~G)
Belief (B) +∞ (heaven) -100 (self-righteous oppression)
Disbelief (~B) −∞ (hell) +100 (freedom and empathy)

The other very overt error in Pascal's Wager are the first two assertions:

1. "God is, or He is not"
2. A Game is being played... where heads or tails will turn up.

This is a logical fallacy: Just because there are two possibilities doesn't mean they are equally likely. If I put 5000 red marbles and one blue marble in a leather pouch and draw a marble there are only two possibilities: I draw a red marble or a blue marble. This doesn't mean that because there are two possibilities they are equally likely outcomes. Do your own research on the next point, although it may end up being my next blog post, but I argue that the odds that there is a god (and beyond that there is not only a god but also the god you chose to believe and that you chose the correct way to worship him or her or it or they) is extremely small such that the best way to live is as though there isn't one.

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