Bob Fischer

Realists about modality offer an attractive semantics for modal discourse in terms of possible worlds, but standard accounts of the worlds—as properties, propositions, or causally-isolated concreta—invoke entities with which we can’t interact. If realism is true, how can we know anything about modal matters? Let's call this "the Benacerraf Problem." I suggest that C. I. Lewis has an intriguing answer to it. Given that we’re willing to disentangle some of Lewis’s insights from his phenomenalism, we can take the following line. If the Benacerraf Problem is a genuine one, then it threatens all knowledge—not just modal knowledge. But then it leads to a general and implausible form of skepticism, not a limited and more plausible debunking argument. Hence, whatever we’re willing to say about skepticism we should say about the Benacerraf Problem.

Persson and Savulescu are advocates for moral bioenhancement—i.e., using drug treatments and genetic engineering to enhance our core moral dispositions. Among other things, they suggest that moral bioenhancement would improve how we treat animals. My goal here is to argue that we have little reason to think that moral bioenhancement will help in this regard. What’s more, it may make things worse. This is because there are cognitive mechanisms that lead us to discount animal interests relative to human interests—mechanisms not overridden by increased altruism and a stronger sense of justice—and there are deep tensions between the interests of humans and animals that moral bioenhancement may well exacerbate.