Why Capacity Matters: Is it fair to treat people like that, like that, for that?

Introduction from my forthcoming chapter in Michael Sevel and Allan McCay’s edited volume Free Will and the Law: New Perspectives.

David Hodgson (2012) thought that responsibility requires what he called “plausible reasoning”, which is reasoning that is not only sound, but also and importantly not completely law-governed. Otherwise, he thought, whether our choices were formed through the operation of natural laws or through the operation of reason’s laws, in both cases our choices would be made for us rather than us choosing those things.

Given this view, the compatibilist idea that responsibility requires the possession of the right kinds of mental capacities in the right degree – on one prominent account, mental capacities required for “moderate reasons-responsiveness” (Fischer and Ravizza 1998) – must have seemed decidedly un-compelling to Hodgson. After all, when a capacitous and an incapacitous person – that is, a person who satisfies the compatibilist mental capacity requirement for responsibility and one who does not – both act wrongly, the law-governed nature of each of their psychologies means that on that occasion neither could actually have acted better. And since on any given occasion when a capacitous person does something wrong, they could no more have done the right thing than an incapacitous person, this raises the question of what difference, in the compatibilist’s own view, psychology is supposed to make for responsibility — that is, as I put it in this paper’s title, why mental capacity matters.

Since this is the topic that this chapter will focus on, I will state this worry another way. Given that on any occasion when a capacitous person does something wrong, their superior psychology gives them no advantage vis-à-vis choosing differently over an incapacitous person, what reason is there to think that capacitous people are more responsible for their acts of wrongdoing (and perhaps more deserving of blame and maybe even punishment) than incapacitous people? What difference is psychology supposed to make for responsibility in the compatibilist’s view, and in virtue of which compatibilists believe that they do not also need that further requirement which Hodgson thought was needed — namely, that reasoning must not only be sound, but also not completely law-governed?

This chapter takes up the challenge of trying to explain why, from a compatibilist perspective, mental capacity matters to responsibility. It also aims to do this in such a way that a jurisprudentially-minded libertarian like Hodgson might find this explanation satisfying. After sketching the concerns that led Hodgson to claim that responsibility requires “plausible reasoning”, and explaining how I think this translates into what I shall call “Hodgson’s Challenge”, I then try to address this challenge. I argue that mental capacity matters because the justification of holding someone responsible for what they did in any given situation derives from whether it would be fair for a system of responsibility – an idea I borrow from Honoré (1999) – to treat people like that (with that kind of psychology), like that (by reacting in that manner to them), for that (for what they did). I also argue that the question of this system’s fairness need not in turn be thought of as a matter of whether that person could have acted otherwise, which would again re-introduce the same problem that my approach was intended to solve, but rather such things as whether this system would treat like cases alike, different cases differently, and be even-handed in how it treats different categories of cases right now and over time.

On my compatibilist account – an account which, as I shall explain, differs from what compatibilists like Fischer and Ravizza and others who have developed their views propose – it thus takes two steps to understand why mental capacity matters, even though on any given occasion people’s psychology (i.e. their mental capacities) can only be exercised in whichever way they actually are exercised (or, if we are talking about an indeterministic system, they are not the ones who indetermine how their psychology will be exercised). First, how a system of responsibility takes account of people’s psychology, in the way that it responds to people on account of the sorts of things that they do, bears on that system’s fairness. Second, the justification in any specific case for holding a given person responsible for what they did in a given way is derived from the justification of the system as a whole under which doing that would be a practice. Mental capacity thus matters for the justifications of systems of responsibility, and at this level it does not matter that on specific occasions individuals cannot exercise their mental capacities differently. But once a system of responsibility is deemed fair, there is no further justificatory question that a compatibilist needs to address regarding why they treat capacitous and incapacitous (or sub-capacitous) people differently. There is, of course, still the question of how to accurately assess what the given person’s psychology actually was like on the occasion of concern when they acted as they did. This is by no means a trivial matter – to assess what a person’s psychology actually was on some given occasion – but it is not the same as the problem of trying to explain why a psychology that on any given occasion can only be exercised in the way that it is exercised (or, yet again, if we are talking about an indeterministic system, why a psychology that is not indetermined in how it is exercised by the will of the person whose psychology it is) can provide a sound normative foundation for distinguishing people from one another qua fully responsible vs. less than fully responsible.

Before proceeding, three notes, and then a brief outline of what follows in this chapter. First, I will use the locutions “why mental capacity matters” and “why psychology matters” interchangeably, and I will also use interchangeably pairs of terms like “capacitous and incapacitous”, “sane and insane”, “mentally sound and mentally unsound”, and “moderately reasons-responsive and not moderately reasons-responsive”. Second, I shall refer to compatibilist views like John Fischer’s as “capacitarian”. Responsible people on Fischer’s account are those who have the mental capacities required to recognize and respond appropriately to reasons – those whose actions issue from moderately reasons-responsive mechanisms – not those who (e.g.) have the metaphysical power or ability to act differently holding fixed the actual history and laws of nature, or who are genuine sources of their own actions, or anything else of a similar ilk. I call such views “capacitarian” because they predicate responsibility (among other things, but on this thing in particular) on how much of which kinds of mental capacities people have. Third, because from my compatibilist perspective the problems for responsibility under determinism and indeterminism are almost identical – whether my actions are determined or indetermined by the laws of nature, either I could not have done otherwise, or if I could have then not I but indeterminism would have seen to that – I will therefore treat the challenges posed by determinism and indeterminism as practically the same challenge. Fourth, here is this chapter’s outline. In section 1 I recount what I take to be Hodgson’s understanding of the threat that determinism (and equally indeterminism) is thought to pose to responsibility; his understanding of the main features of the capacitarian compatibilist strategy for responding to that threat; and his reasons for finding fault with this strategy. Section 2 re-formulates and builds on Hodgson’s critique with the aim of explaining why, as a compatibilist, I find his concerns forceful and worthy of being re-formulated as “Hodgson’s Challenge” to compatibilism. Finally, section 3 develops an approach I have sketched out elsewhere (Vincent 2013), according to which the justification of treating differentially capacitous people differently vis-à-vis their responsibility resides not in features of narrow moments or synchronic time-frames, but in features of whole systems of responsibility that can only be gleaned when we examine how those systems operate diachronically.


Fischer, J. M. and M. Ravizza (1998). Responsibility and Control: A Theory of Moral Responsibility. Cambridge, UK, CUP.
Hodgson, D. (2012). Rationality + Consciousness = Free Will. New York, NY, Oxford University Press.
Honoré, T. (1999). Responsibility and Fault. T. Portland, Oregon, Hart Publishing.
Vincent, N. (2013). “Blame, Desert and Compatibilist Capacity: a diachronic account of moderateness in regards to reasons-responsiveness.” Philosophical Explorations 6(2): 178-194.