Clarke on an alleged asymmetry between PAP and PPA

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Clarke’s 1994 article, ‘Ability and Responsibility for Omissions’ (summarised in a previous post), is a useful and somewhat influential discussion of responsibility with respect to omissions.  In it, Clarke provides an argument against the Principle of Possible Action, which says that “an agent is responsible [for an omission] only if she could have done what she omitted to do” (1994, p. 195).  Despite its influence, there are two reasons to think Clarke’s argument is unsuccessful.

First, the case against PPA rests entirely on the plausibility of Frankfurt-style cases for positive actions.  Here’s how it works: When we reflect on omissions for which we had no ability there and then to avoid (think drunk driving cases), we often appeal to a previous point at which we had an ability to bring something about that would have resulted in action (avoiding the omission).  This is an instance of tracing.  Clarke’s strategy is to argue that it would be possible to apply the standard FSC methodology to any previous ability we might appeal to, meaning that even taking tracing into account, alternative possibilities would still not be available.  Clarke’s argument rests, therefore, entirely on the plausibility of standard FSCs.  The Dilemma Defence, however, provides reason to doubt that standard “prior-sign” FSCs could ever be successful.  Perhaps the earliest formulation of the Dilemma Defence is to be found in a footnote in Kane’s Free will and Values, (1985, pp. 51 n.25).  Forceful expositions are presented in (Widerker 1995) and (Ginet 1996), with a useful summary given in (Timpe 2008, Ch 3).  (Note that one need not be convinced of the success of the Dilemma Defence in order to doubt Clarke’s conclusions: to the extent that standard FSCs provide prima facie reason to doubt PAP, the Dilemma Defence provides prima facie reason to doubt the conclusion of FSCs.  Clarke’s conclusions will be successful only to the extent that one of the complex and highly contentious FSCs (blockage cases, preemption cases, etc) are successful.)

Second, part of Clarke’s explanation for why agents can be responsible in FSC cases, despite the fact that the outcome is unavoidable, is that the outcome nevertheless depends on the agent’s will: had the agent decided otherwise, the omission would not have occurred.  This is a puzzling (and problematic) explanation for two reasons.  First, and as Clarke notes (1994, p. 203), to say such a thing is to attribute to the agent a conditional ability.  But we now seem to be a situation where Clarke wants to maintain that the agent has an ability (albeit a conditional one) to have done otherwise, whilst at the same time saying that the outcome was in fact inevitable (in some strong sense).  But it is typical to say that someone with an ability to do such-n-such possesses the alternative of doing such-n-such.  Indeed, some compatibilist writers have appealed to conditional accounts of ability to argue that agents in FSCs do have alternative possibilities (See (Vihvelin 2000), and for a similar account (Fara 2008)).

The second issue concerning Clarke’s claim that the outcome depends on the agent’s will is that it is false.  Here’s the problem: modal claims expressed by ‘can’ are highly context sensitive.  It is no simple matter to determine whether it is true that had the agent decided otherwise, the omissions would not have occurred.  Moreover, in this particular case, if it is true, it threatens to be irrelevant, because to make the counterfactual true we have to read it as referring to a situation very dissimilar from the actual situation.  We can’t have the agent deciding otherwise whilst also holding fixed the fact that there is an intervener present.  Now, it is possible to assess whether an agent has an ability by considering various counterfactuals.  But when we do so, we have to ask whether the agent is able to bring about the antecedent.  This point (and more) were all forcibly made against the conditional account of ability as it was developed subsequent to Moore’s explicit account of it (Moore 1912, Ch 6).  Lehrer pointed out, for example, that it just can’t be right to say that I have the ability to φ if, were I to choose to φ, I would φ (Lehrer 1968, p. 32).  We have to ask, in addition, whether I could choose to φ.

So it might be true to say that had the agent decided otherwise, the omissions would have been avoided, but only if the agent could have decided otherwise; something which is ruled out, given the FSC.  And so Clarke fails to show that the outcome depends on the agent’s will because the agent in question has no power over what they decide.


Clarke, Randolph (1994): Ability and responsibility for omissions. In Philosophical Studies 73 (2), pp. 195–208. Available online at

Fara, M. (2008): Masked Abilities and Compatibilism. In Mind 117 (468), pp. 843–865.

Ginet, Carl (1996): In defense of the principle of alternative possibilities: Why I don’t find Frankfurt’s argument convincing. In Nous 30, pp. 403–417.

Kane, Robert (1985): Free Will & Values: State University of New York Press.

Lehrer, Keith (1968): Cans without ifs. In Analysis 29 (1), pp. 29–32.

Moore, G. E. (1912): Ethics: Williams and Norgate.

Timpe, Kevin (2008): Free Will: Sourcehood and Its Alternatives: Continuum International Publishing Group Ltd.

Vihvelin, K. (2000): Freedom, foreknowledge, and the principle of alternate possibilities. In Canadian Journal of Philosophy 30 (1), pp. 1–23.

Widerker, David (1995): Libertarianism and Frankfurt’s Attack on the Principle of Alternative Possibilities. In Philosophical Review 104 (2), pp. 247–261.