I remember that! "Pascal's wager" after the mathematician, pretty much exactly as you've described it.

Once, kind of drunk at a party with a bunch of hardcore libertarians who were in denial about global warming, I used it to defend supporting 0 C02 emmissions technology. I called it the green wager, going something like this:

If global warming is false and you support 0 CO2 technology, nothing is harmed, you find useful and marketable alternatives to petrol which you will need down the road anyhow, because oil don't last forever.

On the other hand if global warming is true, and you support 0 CO2 emissions, you've help save all of humanity.

It wasn't an exact fit, but close anyhow...Thanks for the Dennet book recommendation! Sounds fascinating.