This post is based on a discussion with ChristianKl on Less Wrong Chat. Thanks!

Many people disagreed with my previous writings on hypotheticals on Less Wrong (link1, link2). For those who still aren’t convinced, I’ll provide another argument on why you should take hypotheticals seriously. Suppose you are discussing the issue of whether it’d be okay to flick the switch if a train was about to collide with and destroy an entire world as a way to try to sell someone on utilitarian ethics (see trolley problem). The other person objects that this is an unrealistic situation and so there is no point wasting time on this discussion.

This may seem unreasonable, but I suppose a person who believes that their time is very valuable may not feel that it is actually worth their time indulging in the hypothetical that A->B unless the other person is willing to explain to them why this result would relate to how we should act in the real world. This might be especially likely to be true if they have had similar discussion before and so they have a low prior that the other person will be able to relate it to the real world.

However, at this stage, they almost certainly have to update, in the sense that if you are following the rule of updating on new evidence, you have most likely already received new evidence. The argument is as follows: As soon as you have heard A->B (if it would save a world, I would flick a switch), your brain has already performed a surface level evaluation on that argument. Realistically, the thinker in the situation probably knows that it is really tough to make the argument that we should allow an entire world to be destroyed instead of ending one life. Now, the fact that it is tough to argue against something doesn’t mean that it should be accepted. For example, many philosophical proofs or halves of mathematical paradoxes seem very hard to argue against at first, but we may have an intuitive sense that there is a flaw there to be found if we are smart enough and look hard enough.

However, even if we aren’t confident in the logic we still have to update our priors, once we know that there is an argument for it that at least appears to check out. Obviously we will update to a much lesser degree than if we were confident in the logic, but we still have to update to some extent, even if we think...

cansumartin

cansumartin

cansumartin

cansumartin

cansumartin

cansumartin