>So all one has to do is imagine a different set of rights (say the right to do wrong) and then you have no rights. All this is is "what if we both happened to imagine the same rights?" But what if we don't? What if we had the conflict of John and Bill as discussed in the piece? Do we then not have rights?

yes?

how do you think morals are defined and chosen by societies? through popularity and force.

ie if socialist authoritarism had successfully beaten and replaced capitalist democracy across the globe then it would be considered moral by the majority.