I should have said something about marginal utility there. Doesn't change the three tests for a Pascal scam though.
The asteroid threat is a good example of a low-probability disaster that is probably not a Pascal scam. On point (1) it is fairly lottery-like, insofar as asteroid orbits are relatively predictable -- the unknowns are primarily "known unknowns", being deviations from very simple functions -- so it's possible to compute odds from actual data, rather than merely guessing them from a morass of "unknown unknowns". It passes test (2) as we have good ways to simulate with reasonable accuracy and (at some expense, only if needed) actually test solutions. And best of all it passes test (3) -- experiments or observations can be done to improve our information about those odds. Most of the funding has, quite properly, gone to those empirical observations, not towards speculating about solutions before the problem has been well characterized.
Alas, most alleged futuristic threats and hopes don't fall into such a clean category: the evidence is hopelessly equivocal (even if declared with a false certainty) or missing, and those advocating that our attention and other resources be devoted to them usually fail to propose experiments or observations that would imrove that evidence and thus reduce our uncertainty to levels that would distinguish them from the near-infinity of plausible disaster scenarios we could imagine. (Even with just the robot apocalypse, there are a near-infinity of ways one can plausibly imagine it playing out). Same, generally speaking, for future diseases -- there may well be a threat lying in there, but we don't have any general ways of clearly characterizing specifically what those threats might be and thus distinguishing them from the near-infinity of threats we could plausibly imagine (again generally speaking -- there are obviously some well-characterized specific diseases for which we do have such knowledge).
Nick Szabo on acting on extremely long odds with claimed high payoffs:
Beware of what I call Pascal's scams: movements or belief systems that ask you to hope for or worry about very improbable outcomes that could have very large positive or negative consequences. (The name comes of course from the infinite-reward Wager proposed by Pascal: these days the large-but-finite versions are far more pernicious). Naive expected value reasoning implies that they are worth the effort: if the odds are 1 in 1,000 that I could win $1 billion, and I am risk and time neutral, then I should expend up to nearly $1 million dollars worth of effort to gain this boon. The problems with these beliefs tend to be at least threefold, all stemming from the general uncertainty, i.e. the poor information or lack of information, from which we abstracted the low probability estimate in the first place: because in the messy real world the low probability estimate is almost always due to low or poor evidence rather than being a lottery with well-defined odds.
Nick clarifies in the comments that he is indeed talking about singularitarians, including his GMU colleague Robin Hanson. This post appears to revisit a comment on an earlier post:
In other words, just because one comes up with quasi-plausible catastrophic scenarios does not put the burden of proof on the skeptics to debunk them or else cough up substantial funds to supposedly combat these alleged threats.