This is a good argument against Pascal’s Wager, but it isn’t the least convenient possible world. The least convenient possible world is the one where Omega, the completely trustworthy superintelligence who is always right, informs you that God definitely doesn’t value intellectual integrity that much. In fact (Omega tells you) either God does not exist or the Catholics are right about absolutely everything.
Would you become a Catholic in this world? Or are you willing to admit that maybe your rejection of Pascal’s Wager has less to do with a hypothesized pro-atheism God, and more to do with a belief that it’s wrong to abandon your intellectual integrity on the off chance that a crazy deity is playing a perverted game of blind poker with your eternal soul?
This is a bad example. Pascal’s wager wasn’t a thought experiment. Pascal genuinely believed that the two options his wager proposed were the only options. Not hypothetically, but in real life. He wasn’t asking, “If this were the case, would you wager that God exists?” He was saying, “This is the case, and so you’d be stupid not to wager that God exists, QED” It’s not fighting the hypothetical to say “Those aren’t the only two options”, because the problem as Pascal viewed it wasn’t hypothetical in the slightest. He was making an argument, and the rebuttal to his argument is to point out that it relies on flawed assumptions.
This is the way I think about it:
Given how good Omega is at predicting people’s decisions, I should assume that a world where I choose to take both boxes cannot coincide with a world where Omega predicted I would only take one box. In other words, the payoff matrix that creates this paradox in the first place is an illusion, because the scenario in which you two-box and get $1,001,000 simply doesn’t exist. Or at the very least, it is so unlikely to exist that you should behave as though it doesn’t.