“Let’s say you think utilitarianism is true with some probability, and Kantian deontology is also true with some probability. Can you aggregate the recommendations of these two theories “across the probabilities”? Not easily. The Kantian theory offers an absolute recommendation, but should that carry the day if deontology is true with only 7%? More generally, even less absolute theories do not offer comparable frameworks for cross-theoretical aggregation. How does 6% truth for maximin, 13% truth for prioritarianism, and 27% truth for cosmopolitan utilitarianism all add up? It’s not like calculating true shooting percentage in the NBA, because there is no common and commensurable understanding of “points” across the different frameworks. This aggregation problem is actually tougher than Arrow’s, at least once we recognize there is justifiably uncertainty about the true moral theory.”

— Tyler Cowen, The difficulty of cross-theoretical aggregation