But the post is an argument for using cardinal utility (VNM utility)! And Arrow’s “impossibility” theorem only applies when trying to aggregate ordinal utilities across voters. It is well-known that voting systems which aggregate cardinal utility, such as Range Voting can escape the impossibility theorem.
So Arrow is actually another reason for having a VNM utility function: it allows collectively rational decisions, as well as individually rational decisions.
But the post is an argument for using cardinal utility (VNM utility)! And Arrow’s “impossibility” theorem only applies when trying to aggregate ordinal utilities across voters. It is well-known that voting systems which aggregate cardinal utility, such as Range Voting can escape the impossibility theorem.
So Arrow is actually another reason for having a VNM utility function: it allows collectively rational decisions, as well as individually rational decisions.