Pascal’s wager revisited

It is always interesting to find out how different people have different understanding of things. Recently I found a link to a video made by school teacher Greg Craven: A guy with a marker aims to make the global warming debate obsolete. The site that provided the link brought it as “an example of engaging and effective science communication“.

Well, that sounds promising!

According to the author it is possible to choose how best to act on the issue of Global Warming (he uses both Global Warming and Climate Change) without knowing something about the science of it. That is interesting. When I started looking at the global warming issue about five years ago, I also was searching for a way to find if the arguments about global warming were true or not. I found that in some cases this is possible (when certain logical fallacies were used), but in most cases it is necessary to know at least something about the science. I am a bit skeptical hearing him say no knowledge of the science is needed.

This is how it is presented: if we can’t be sure if global warming is true and we want to know what action to take, we can make a table in which we put the outcome of different possible scenario’s. On the left the question: “is Global warming true or false”? On top the question: “do we take significant action now”? From that outcome of these questions he claims it is possible to decide what is the best option to take right now.

Climate Change wager

Climate Change wager.

This is nothing new, I saw similar reasonings before. It looks very similar to Pascal’s wager. This says that “it is safer to believe in God, even if there is no proof that one exists”. Pascal’s starting point was also that it was not necessary to know something about the existence of God to know what do in our life. This is how Pascal saw it:

Pascal's wager

Pascal’s wager.

Pascal also wrote down the different outcomes of possible scenarios. These are the outcomes

    If we believe and:

  • God doesn’t exist: we lost some time worshiping and weren’t able to do things we probably would like to do → finite sadness (until we die).
  • God does exist: we go to heaven and are rewarded for our efforts with eternal bliss → infinite happiness (forever and ever).
    If we don’t believe and:

  • God doesn’t exist: we didn’t loose some time worshiping and did everything we liked without restriction → finite happiness (until we die).
  • God does exist: we go to hell and are punished with eternal misery → infinite sadness (forever and ever).

So if God exists, the reward and the penalty are huge (because they are forever). If God doesn’t exists, the reward and the penalty would be minor (because we have short lives). Therefor his conclusion was that it is better to believe in God because the outcome is better when we believe than when we don’t believe.

So far so good, but as I learned in school this wager is based on an array of logical fallacies and he cherry picked a bunch of assumptions that lead directly to this conclusion, therefor invalidating it. For example, in the wager Pascal assumed the God to be the God we know in this part of the world and that this is the “right” God. He also assumed that there is an afterlife and that believing in God is enough for eternal bliss and failing to believe will give eternal misery. Also that this God cares or is fair. That one can get away with calculated worship. Etcetera, etcetera. There are many others. A lot of books have been written about this wager.

As far as I know, the Craven’s wager has basically the same problems as Pascal’s wager.

It gives about the same outcomes as the Pascal wager. He adds that we can’t choose which row we want to be in, but we can choose in what column. He likens it with a lottery ticket. For example if we buy lottery ticket A then it will cost us a lot of money in both cases (we will ruin our economy whether global warming is true or not). But when buying lottery ticket B it is possible to have a rather nice reward if global warming is false, but a really nasty one if it is true.

Therefor he says that it is better to choose ticket A: we will loose money, guaranteed. But when we buy lottery ticket B, the outcome is much more uncertain: it is or extremely good (if climate change doesn’t exists) or extremely bad (if it does). So, if we want to avoid the extremely bad, we need to choose ticket A. In which we will have to pay a lot of money whether climate change is true or not, but if it is true we would survive it.

The author makes the suggestion for everyone to remake this for other outcomes (also the less extreme ones), but adds that whatever scenario you will choose, it will always come to the inescapable conclusion that ticket A will be better than ticket B…

But is this really true?

In analogy with the Pascal wager, this “inescapable” result is completely dependent on the smiley face in the bottom left quadrant; combined with the over-the-top dramatic scenario in the bottom right. If both scenario’s are taken as constants, the only sensible choice will indeed be ticket A. The over-the-top scenario of ticket B will overshadow the grim outlook of both scenario’s in ticket A. But I could imagine other scenario’s in which this is not necessarily the case and then ticket B might be much more interesting.

Let’s go through all quadrants and see what the range of possible scenario’s will be.

The only quadrant that we really can be sure of is the one on the top right. This means: we didn’t spend any money to prevent global warming, but it was not needed. Whatever scenario you choose, there will alway be a happy face in that quadrant.

The values in the three other quadrants will depend on the assumptions made and will be somewhere between the best case scenario and the worst case scenario.

In the top left quadrant he assumed: we spend money where it was not needed and we came into a (global) recession. That is the worst case scenario. The best case would be for example: we spend money, but we could afford it and spending it didn’t hurt us much.
All other options would be between those two.

In the bottom left quadrant he assumed that Climate Change existed, we took action and we came to the solution. That is in fact the best case scenario, not the worst as he assumes. Worst case would be: Climate Change exists, we did spend money on it trying to prevent it, but it didn’t work out (we spend it on the wrong solution, it wasn’t preventable anymore or whatever). In that case we would be with much less money and still facing the horrors of Climate Change. Like the victims of Haiyan who were unprepared for it.
All other options will be between those two.

In the bottom right quadrant he assumed that Climate Change existed, no action was taken and all the horrors of the world come at once and catapults us into oblivion. That is the worst case scenario. The best case scenario is that Climate Change exists, we took no action to prevent it and it was possible to adapt to it with not much effort.
All other options will be between those two.

Now we start all over and go for the two extremes (the real extremes, not the assumed ones):

  • When we take the worst case scenarios in all cases, we will likely choose ticket A. So far so good. That was also the conclusion of the author
  • But when we take the best case scenarios in all cases, we will likely choose ticket B.

In the end this exercise will learn us exactly nothing, except that the scenarios will depend on how one defines the assumptions for the different scenarios.

Just as the Pascal’s wager this wager it starts from a number of assumptions. For example that climate change is preventable by us, that we would be safe when we do something now, that the outcome of not acting is dramatic, that it is not possible to adapt and many, many more. Therefor the conclusion was skewed to ticket A.

This was a system assumed for those who have no knowledge of the science, but those are now presented with a one-sided presentation of the facts. But either way, my opinion is that when one starts from the premise that it is not necessary to know if global warming is true/false or if it is happening/not happening, then this table is useless to find out what the best option really is. Making this just a modern version of Pascal’s Wager, numerous assumptions and fallacies included.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s