¹ See Mason, Elinor, ‘Consequentialism and the “Ought Implies Can” Principle’, American Philosophical Quarterly 40 (2003) pp. 319–31Google Scholar, and Andric, Vuko, ‘Objective Consequentialism and the Rationales of “Ought” Implies “Can”’, Ratio 29 (2015), pp. 1–16.Google Scholar

² At least, as Kant is normally interpreted. There is some controversy here. See Stern, Robert, ‘Does “Ought” Imply “Can”? And Did Kant Think It Does?’, Utilitas 16 (2004), pp. 42–61 CrossRefGoogle Scholar, for more details.

³ See in particular the essays collected in Gowans, Christopher, Moral Dilemmas (New York, 1987)Google Scholar and Mason, H. E., Moral Dilemmas and Moral Theory (Oxford, 1996)Google Scholar.

⁴ On determinism and free will see Haji, Ishtiyaque, Moral Appraisability: Puzzles, Proposals, and Perplexities (New York, 1998)Google Scholar; Haji, ‘Moral Anchors and Control’, Canadian Journal of Philosophy 29 (1999), pp. 175-203; Haji, Deontic Morality and Control (New York, 2002). On alternative possibilities see van Inwagen, Peter, An Essay on Free Will (Oxford, 1983)Google Scholar; Widerker, David, ‘Frankfurt on “Ought Implies Can” and Alternative Possibilities’, Analysis 51 (1991), pp. 222–4CrossRefGoogle Scholar; Copp, David, ‘Defending the Principle of Alternate Possibilities: Blameworthiness and Moral Responsibility’, Nous 31 (1997), pp. 441–56CrossRefGoogle Scholar; Copp, ‘“Ought” Implies “Can”, Blameworthiness, and the Principle of Alternate Possibilities’, Moral Responsibility and Alternative Possibilities: Essays on the Importance of Alternative Possibilities, ed. M. McKenna and D. Widerker (Burlington, VT, 2003), pp. 265–99.

⁵ For an appeal to the principle to argue against subjectivism, see Graham, Peter, ‘“Ought” and Ability’, Philosophical Review 120 (2011), pp. 337–82CrossRefGoogle Scholar. Against objectivism (objective utilitarianism in particular), see again Mason, ‘Consequentialism’ and Andric, ‘Objective Consequentialism’.

⁶ Hare, R. M., Reason And Freedom (Oxford, 1963)Google Scholar; Driver, Julia, ‘Promises, Obligations, and Abilities’, Philosophical Studies 44 (1983), pp. 221–3CrossRefGoogle Scholar; Williams, Bernard, ‘Internal Reasons and the Obscurity of Blame’, Making Sense of Humanity (Cambridge, 1989)Google Scholar, pp. 35--45; Griffin, James, ‘The Human Good and the Ambitions of Consequentialism’, Social Philosophy and Policy (1992), pp. 118--32Google Scholar; Copp, ‘ “Ought” Implies “Can”, Blameworthiness, and the Principle of Alternate Possibilities’, and Andric, ‘Objective Consequentialism’.

⁷ Martin, Wayne, ‘Ought But Cannot’, Proceedings of the Aristotelian Society 109 (2009), pp. 103–28CrossRefGoogle Scholar; Jay, Christopher, ‘Impossible Obligations Are Not Necessarily Deliberatively Pointless’, Proceedings of the Aristotelian Society 113 (2012), pp. 381–9CrossRefGoogle Scholar; Stern, ‘Does “Ought” Imply “Can”?’.

⁸ If we put aside the act/omission distinction (as I will, since it is not important here) not-φ-ing is equivalent to performing another act, φ*. So if you are permitted to not-φ if you are unable to not-φ, then you are permitted to φ* if you are unable to φ*. Thus we must conclude that inability entails permissibility.

⁹ It has also been suggested to me by a referee that action guiders can avoid a forced march to the absurd conclusion that everything impossible is morally permissible by replacing premise (4) above with (4*): If you are morally obligated to φ, then in so far as deliberation about whether or not to φ is rationally permissible, you can be guided in your (rational) deliberation about whether or not to φ by the fact of your obligation to φ. I have to confess that I do not see how an argument can be derived from this premise that is both valid and avoids a forced march to the absurd conclusion.

¹⁰ It might be tempting to think that statements of the form ‘S is permitted to φ’ don't pragmatically implicate that S would be permitted to φ if he was able to, but rather express the proposition that ‘S is permitted to φ if he/she is able to’. But that can't be right. If it was, then to assert ‘He is permitted to speak up, but I don't mean to suggest that he would still be permitted to do so were he actually able to’ would be tantamount to asserting ‘He is permitted to speak up if he is able to, but I don't mean to suggest that he is permitted to speak up were he able to’, which is clearly self-contradictory. But the assertion ‘He is permitted to speak up, but I don't mean to suggest that he would still be permitted to do so were he actually able to’ doesn't sound self-contradictory, it sounds fine. So the suggestion that ‘S is permitted to φ’ expresses the proposition ‘S is permitted to φ if he/she is able to’ is not plausible.

¹¹ To be clear, I don't mean to suggest that the duality principle should be treated as indefeasibly immune to the possibility of revision. As Sayre-McCord, Geoffrey (‘Deontic Logic and The Priority of Moral Theory’, Nous 20 (1986), pp. 179–97)CrossRefGoogle Scholar has pointed out, no principle of deontic logic should be. However, it is one thing to think that the principle is potentially revisable, if the price is worth paying, and quite another to think that the price is in fact worth paying. It is, I think, doubtful that a good case can be made for rejecting the principle in this context. At any rate, it is incumbent on action guiders to make the case if there is one to be made. On this issue, a referee has pointed out to me that moral error theorists such as Olson, Jonas, in Moral Error Theory: History, Critique, Defence (Oxford, 2014)CrossRefGoogle Scholar, and Pigden, Charles, in ‘Nihilism, Nietzsche and the Doppelganger Problem’, Ethical Theory and Moral Practice 10 (2007), pp. 441–56CrossRefGoogle Scholar, who deny that there are any moral properties, reject the duality principle, and that they do so not do in order to save the OIC principle. Rather, they reject it in order to make sense of the idea that statements of the form ‘S is morally obligated to φ/not-φ’ and ‘S is morally permitted to φ/not-φ’ are universally false, which would be an incoherent view if the duality principle were sound. Can this line of argument help rescue the action guidance argument? I don't think so. For one thing, it is far from clear that a view according to which moral statements are universally false is in fact coherent. But even putting that aside, moral error theorists will (or at least, should) accept a restricted version of the duality principle according to which, if φ-ing has moral properties, then φ-ing is not obligatory iff not φ-ing is permitted (i.e. (Mφ) → (¬ Oφ ↔ P ¬ φ)). Of course, moral error theorists will think that the antecedent of this conditional is always false, but that in itself provides them with no reason to reject the conditional itself. The important point here is that, as we will see, everything I want to do in this article can be done with this restricted principle. This is because, as I'll show shortly, action guidance considerations provide us with no reason to reject the idea that φ-ing can be morally permissible even when one cannot φ (or cannot but φ). A fortiori, action guidance considerations give us no reason to think that impossible actions lack moral properties.

¹² Since our aim is to see if the action guidance argument can be rescued from the problem I have presented for it, it is crucial that the motivation for the permission-entails-ability principle comes from action guidance considerations, rather than something else. Given that ‘S is obligated to φ’ plausibly entails ‘S is permitted to φ’, if our reason for thinking that ‘S is permitted to φ’ lacks a truth value when S cannot φ comes from something other than action guidance considerations, then what we will have on our hands won't be a shoring up of the action guidance argument, but rather a wholesale replacement of it with something else, for the considerations that motivated the idea that permission-entails-ability would also motivate the OIC principle all by themselves. The action guidance argument would thereby be rendered superfluous; a spinning wheel without any dialectical grip of its own. But as I said earlier, my aim here isn't to evaluate every possible argument for the OIC principle; it is only to evaluate the action guidance argument in particular. One might, for example, argue that permissibility-entails-ability on broadly Kantian grounds. But given that such a Kantian argument, if sound, would motivate the OIC principle all by itself, it cannot be used to shore up the action guidance argument; instead it would simply render that argument redundant. It wouldn't be action guidance considerations motivating the OIC principle; it would be the Kantian argument. Thanks to two anonymous referees for pointing out the need for clarification on this point.

¹³ Action guiders might want to respond to this argument by saying that a permission to φ is guiding when I have no reason to φ because I could have had a reason to φ, and in the counterfactual world in which I do the fact that I am permitted to do so can serve to guide my deliberation. But this won't help. Even if I lack the ability to φ, I could have had the ability to φ (except if φ-ing is metaphysically impossible). So if we are going to allow guidance in counterfactual worlds into our understanding of what it is for a permission to be guiding, then we can have no objection to the idea that a permission to φ is guiding even when one cannot φ, because it guides deliberation in counterfactual worlds in which one can φ. So the idea that action guidance considerations motivate the view that permissibility entails ability is still unmotivated.

¹⁴ At least, assuming that moral particularism is false.

¹⁵ Thanks to Daniel Greco, Torfinn Huvenes, Herman Cappelen, Juhani Yli-Vakkuri, Peter Fritz, an audience at University College Dublin, and two anonymous referees for Utilitas for helpful comments on arlier drafts of this article.