Toward a Kantian Metaethic

Abstract

In this dissertation, I argue for a metaethical theory I call Kantianism, so called because it embodies some of the spirit of Immanuel Kant’s practical philosophy. I first argue for Kantianism by arguing against one of its chief rivals, substantive realism, on motivational grounds. I then offer a second argument for Kantianism, also by arguing against substantive realism, but this time partly on motivational and partly on explanatory grounds. In response to the objection that my arguments for Kantianism presuppose the existence of morality and so are ineffective against moral nihilism, I contend that what really matters are whether rational agency exists and whether the claims I make about it—in particular, that rational agents, simply in virtue of truly exercising their rational agency, choose only laws—are true. Accordingly, I argue that we are justified in believing in rational agency; that rational agents, simply in virtue of truly exercising their rational agency, do indeed choose only laws; and I briefly attempt to derive a couple substantive moral facts from this abstract truth about rational agency.