This "collective belief" is somewhat more than mere "belief".
It has been translated into laws and social contracts backed by established enforcement that is sufficiently effective and has been demonstrated to the satisfaction and judgment of most people.
It's true that in the event of nuclear war, this could all evaporate --- but this probabilty is low enough for most people to reasonably ignore. Labeling this a "belief" is thus somewhat disingenous in the fact that it is reason rooted in logic and judgment and probability.
It has been translated into laws and social contracts backed by established enforcement that is sufficiently effective and has been demonstrated to the satisfaction and judgment of most people.
It's true that in the event of nuclear war, this could all evaporate --- but this probabilty is low enough for most people to reasonably ignore. Labeling this a "belief" is thus somewhat disingenous in the fact that it is reason rooted in logic and judgment and probability.