Abstract

There are various ways of characterising Hume’s dictum that ‘you can’t get an ought from an is.’ Contributors to the literature directly addressing this question focus on logical characterisations of autonomy theses. Such theses maintain that certain logical relations do not obtain between ethical and non-ethical sentences, for instance that no non-ethical sentences logically entail an ethical sentence. I argue that this focus on logical autonomy is a mistake. The thesis so important to our metaethicists is not a logical thesis but a metaphysical one. The relevant metaphysical autonomy thesis maintains that ethical facts are not fully grounded just in non-ethical facts. I defend this characterization. I also defend the converse thesis that all facts partly grounded in ethical facts are ethical facts. I then argue that this pair of theses can help with debates about the plausibility of nihilism and the classification of revisionary metaethical theses