I agree with you that observational selection effects are important here.
Our causal model of reality tells us that if there were a nuclear exchange between the superpowers, there is a good chance we or our ancestors would’ve died, and once dead, would’ve been unable to engage in this conversation (or to produce offspring to engage in this conversation). This information needs to be taken into account in certain situations, e.g., when estimating the likelihood of a nuclear war in the future.
In particular, if nuclear weapons suddenly appeared for the first time today, we would have some guess, some probability of their being used in anger (in the future). Our knowledge that they’ve existed since 1946 without having been used lowers that probability. I.e., it is evidence against their being used in the future, but it is weaker evidence than it would have been if we were immune to the effects of the weapons, i.e., if we were equally able to observe their past use as we are their past non-use.
Moreover, suppose you, your parents and your grandparents were dependent for their income on their ownership of a sporting-goods store in Washington, D.C. D.C. is of course a likely to be targeted with many bombs in any nuclear war between the superpowers, and any owner of a sporting-goods store is likely to stay in or near the store whenever looting is likely (at least if their family’s income depends on the store). Then the fact that there was no nuclear war between 1946 and today is less informative to you than it is to someone whose ancestors lived somewhere unlikely to be targeted (e.g., New Zealand). The person in New Zealand can of course communicate their observations to you, but if you’re being sufficiently rational, you have to consider their communications biased in the same way that you have to consider the communications of, e.g., a drug company to be biased if you suspect that the drug company is likely to withhold information that shows their drug to be harmful.
I agree with you that observational selection effects are important here.
Our causal model of reality tells us that if there were a nuclear exchange between the superpowers, there is a good chance we or our ancestors would’ve died, and once dead, would’ve been unable to engage in this conversation (or to produce offspring to engage in this conversation). This information needs to be taken into account in certain situations, e.g., when estimating the likelihood of a nuclear war in the future.
In particular, if nuclear weapons suddenly appeared for the first time today, we would have some guess, some probability of their being used in anger (in the future). Our knowledge that they’ve existed since 1946 without having been used lowers that probability. I.e., it is evidence against their being used in the future, but it is weaker evidence than it would have been if we were immune to the effects of the weapons, i.e., if we were equally able to observe their past use as we are their past non-use.
Moreover, suppose you, your parents and your grandparents were dependent for their income on their ownership of a sporting-goods store in Washington, D.C. D.C. is of course a likely to be targeted with many bombs in any nuclear war between the superpowers, and any owner of a sporting-goods store is likely to stay in or near the store whenever looting is likely (at least if their family’s income depends on the store). Then the fact that there was no nuclear war between 1946 and today is less informative to you than it is to someone whose ancestors lived somewhere unlikely to be targeted (e.g., New Zealand). The person in New Zealand can of course communicate their observations to you, but if you’re being sufficiently rational, you have to consider their communications biased in the same way that you have to consider the communications of, e.g., a drug company to be biased if you suspect that the drug company is likely to withhold information that shows their drug to be harmful.