You’re not making much sense.
The OP says a) if most vote blue then nobody dies, else blue-voters die.
I say b) if I pay the gunman £100,000 then nobody dies, else his hostages die.
The fact that (a) is said in the 1st comment of the discussion and (b) is said in the 670th comment of the discussion doesn’t mean that you get to ask “how do I know that (b) is true?” but I don’t get to ask “how do I know that (a) is true?”.
For the purpose of this discussion we just ought accept that both (a) and (b) are known to be true, and then ask ourselves what we should do in these scenarios.
My argument is that the reasoning you use in (a) to conclude that we ought vote blue entails that I ought pay £100,000 in (b), that it is not the case that I ought pay £100,000 in (b), and so that your reasoning in (a) is a non sequitur. Counterfactual causal responsibility does not entail moral responsibility.
This raises interesting implications.
If I said today in the 1500th year of chess that in chess the rule is that the rook can move diagonally, is it now true that in chess the rook can move diagonally?
Why should the rule established in the 1st year of chess that the rook can only move in a straight line take precedence as being the true rule?
Why should the statement in the 1st comment of this thread about red and blue buttons, the OP, be accepted without question as being a true description, yet the 670th comment about gunmen not be accepted as a true description without questioning?
Why should truth be temporal, in that earlier rules are accepted as being true yet later rules are not accepted as being true without being questioned?
Why in chess do we agree that the rook can only move in a straight line rather than diagonally?
The benefit of the blue button is that it gives some the possibility of an exit, if the reds win a majority. All reds get to keep their lives and blues get the gift of a (painless?) exit. A lot of days I think my life isn’t worth the trouble.
The psychological priming of how the choice is worded is possibly an issue, though maybe it wouldn’t make much of a difference if the entire global population is voting. Is there uncertainty in suffering while dying or do we not even realize we’ve pushed the blue button because we cease instantaneously.
We’re to assume that no public communication and consensus prior to the formal vote is possible, that somehow everyone is suddenly trapped in a version of the prisoner’s dilemma.
Otherwise I think I’d ask my family how they want me to vote, if they’d prefer I remain alive with absolute certainty or not.
There might be a hidden purple button somewhere. It might be irrational to press it because we don’t know what it does.