A Remark on Iffy Oughts

Since it was presented in 1963, Chisholm’s paradox has attracted constant attention in the deontic logic literature, but without the emergence of any definitive solution. We claim this is due to its having no single solution. The paradox actually presents many challenges to the formalization of deontic statements, including (1) context sensitivity of unconditional oughts, (2) formalizing conditional oughts, and (3) distinguishing generic from nongeneric oughts. Using the practical interpretation of ‘ought’ as a guideline, we propose a linguistically motivated logical solution to each of these problems, and explain the relation of the solution to the problem of contrary-to-duty obligations.

Annals of Mathematics and Artificial Intelligence, 1993

Nous, 1998

Ergo an Open Access Journal of Philosophy

A contrary-to-duty obligation (CTD obligation) is a type of conditional obligation that tells us what to do when a primary duty is violated. Chisholm’s Paradox is one of the most famous deontic puzzles about CTD obligations. It is widely believed that Chisholm’s Paradox does not arise for ordering semantics, today’s orthodox semantics for modals and conditionals. In this paper, I propose a new puzzle, the CTD Trilemma, to show that ordering semantics still has difficulties in adequately representing natural reasoning with CTD obligations. I argue that to solve the CTD Trilemma a formal account must attend to two different functions played by ought-statements in our normative reasoning and discourse: ought-statements as normative rules and normative judgments. To formally capture this distinction I develop a new dynamic account of ought-statements and normative reasoning inspired by Frank Veltman’s update semantics for default reasoning. Finally, I show how my update semantics for no...

Trends in Logic, 1997

Philosophy and Phenomenological Research

In the classic Miners case, an agent subjectively ought to do what they know is objectively wrong. This case shows that the subjective and objective ‘oughts’ are somewhat independent. But there remains a powerful intuition that the guidance of objective ‘oughts’ is more authoritative—so long as we know what they tell us. We argue that this intuition must be given up in light of a monotonicity principle, which undercuts the rationale for saying that objective ‘oughts’ are an authoritative guide for agents and advisors.

Noûs, 1974

dialectica

Stephen Finlay analyses ‘ought’ in terms of probability. According to him, normative ‘ought’s are statements about the likelihood that an act will realize some (contextually-supplied) end. I raise a problem for this theory. It concerns the relation between ‘ought’ and the balance of reasons. ‘A ought to Ф’ seems to entail that the balance of reasons favours that A Ф-es, and vice versa. Given Finlay’s semantics for ‘ought’, it also makes sense to think of reasons and their weight in terms of probability. In this paper, I develop such a theory of weight. It turns out, however, that it cannot explain the entailments. This leaves Finlay with a challenge: to explain these entailments in some other way consistent with his theory, or to show why the appearances deceive and there are no such entailments.

Deontic Modality, 2016