Here is my attempt to make the shortest possible summary of UPB:
Of course, a skeptic can still dispute Stef's conception of what argument actually presupposes. What argument does Stef present to support his idea of strong universality? Is it possible that moral propositions that pass the UPB test could contradict each other? I'm not sure how to answer those questions, but I want to think about them and others. If you have suggestions, please add them to the comments section.