Normative Externalism, by Brian Weatherson

Abstract

Rohana faces a choice where she can produce either a better outcome by lying or a worse outcome by telling the truth. She justifiably, but falsely, believes in a Kantian moral theory that prohibits lying. (She encountered persuasive defences of Kantian ethics in college, and never encountered the rebuttals to those defences.) In fact, the true moral theory is a form of consequentialism, according to which Rohana should lie for the greater good. Pretty clearly, then, there is an important sense in which Rohana should lie. (For instance, it is what she would do if she were ideally informed and motivated.) But is there also an important sense in which Rohana should tell the truth, since she justifiably accepts a moral principle that tells her to do so? Aldaris faces a choice where he can either (A) benefit a human being by 10 welfare units, (B) benefit a pig by 20 welfare units, or (C) benefit the human being and the pig by 9 welfare units each. (This case is a slight variant of one described by MacAskill, 2014, pp. 9–11.) Aldaris is uncertain which of two moral theories is true, giving equal credence to each: a hedonistic utilitarian theory, according to which he ought to maximize total welfare, or a contractualist theory, according to which (in situations like this) he ought to maximize human welfare. Aldaris is a moral philosopher who has thought long and carefully about these two theories, and his uncertainty between them is justified. But in fact, the contractualist theory is true. So clearly there is a sense in which Aldaris should choose (A), since this is the option preferred by the true moral theory. But is there also a sense in which he should choose (C), since it is nearly optimal according to both moral theories in which he has credence?