Abstract:Many philosophers claim that it cannot be the case that a person ought to perform an action if this person cannot perform this action. However, most of these philosophers do not give arguments for the truth of this claim. In this paper, I argue that it is plausible to interpret this claim in such a way that it is entailed by the claim that there cannot be a reason for a person to perform an action if it is impossible that this person will perform this action. I then give three arguments for the truth of the latter claim, which are also arguments for the truth of the former claim as I interpret it.

This book defends an error theory about all normative judgements: not just moral judgements, but also judgements about reasons for action, judgements about reasons for belief, and instrumental normative judgements. This theory says that normative judgements are beliefs that ascribe normative properties, but that normative properties do not exist. It therefore entails that all normative judgements are false. The book also argues, however, that we cannot believe this error theory. Instead of being a problem for the theory, the book argues, our inability to believe this error theory makes the theory more likely to be true, since it undermines objections to the theory, it makes it harder to reject the arguments for the theory, and it undermines revisionary alternatives to the theory. The book then sketches how certain other philosophical theories can be defended in a similar way, and how philosophers should modify their methodology if there can be true philosophical theories that we cannot believe. It concludes that to make philosophical progress, we should make a sharp distinction between a theory’s truth and our ability to believe it.

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Abstract:Walter Sinnott-Armstrong argues that 'ought' does not entail 'can', but instead conversationally implicates it. I argue that Sinnott-Armstrong is actually committed to a hybrid view about the relation between 'ought' and 'can'. I then give a tensed formulation of the view that 'ought' entails 'can' that deals with Sinnott-Armstrong's argument and that is more unified than Sinnott-Armstrong's view.

What is the relation between entailment and reasons for belief? In this paper, I discuss several answers to this question, and I argue that these answers all face problems. I then propose the following answer: for all propositions p 1 ,. . .,p n and q, if the conjunction of p 1 ,. . ., and p n entails q, then there is a reason against a personÕs both believing that p 1 ,. . ., and that p n and believing the negation of q. I argue that this answer avoids the problems that the other answers to this question face, and that it does not face any other problems either. I end by showing what the relation between deductive logic, reasons for belief and reasoning is if this answer is correct.