At the moment, usually in the context of discussions about Article 12 of the UN Convention of the Rights of Persons with Disabilities, the very idea of mental capacity is coming under attack. That’s good. If the concept can’t take a good battering, then it doesn’t deserve to.
To stretch the ‘battering’ metaphor a bit further though, some of the attacks look more like someone wildly windmilling their arms in the rough direction of a target than like Jet Li taking down the White Lotus Society. I think a lot of it comes down to a failure to unequivocally take a side when criticising the concept. This happens at least three ways.
First, sometimes people think an argument that everyone is irrational adds strength to the UNCRPD inspired idea that everyone, no matter what their disability, is able to make their own decisions (sometimes, Kahneman’s ‘Thinking, Fast and Slow’ is mentioned in this regard, but see Retraction Watch). This is silly. Arguing that everyone is irrational obviously doesn’t support a claim that some people are more rational than we have been treating them. Rather than defending the claim of people with disabilities are able to make their own decisions, claiming humans are irrational undercuts everyone’s claim to be able to make their own decision.
In other words, the concept of capacity can be attacked from either extreme: either because everyone (or maybe just more people than we admit) is rational, or because everyone is irrational. It can’t be attacked from both sides by the same person, though, if that person wants to be taken seriously. If you say to me, ‘that car is mine because I bought it’ or if you say ‘it’s OK that I stole that car because all property is theft anyway’, then we can talk about that. If you say to me, ‘that car is mine because I bought it, and anyway it’s OK that I stole it because all property is theft’, I’m going to think that you’re a self-serving liar.
Worse than this, arguing that no-one is really rational is a claim that eats itself. If no-one is rational, then reform, and the law, and argument, and arguing that people are irrational are all just so many pointless dead words. To speak to another person is to assume that they are responsive to reasons.
This phrase, ‘responsive to reasons’ brings up the second ambiguity. There are, broadly, two common ways of talking about reason and rationality. Let’s call them the maximalist and minimalist versions. On the maximalist version, ‘reason’ means something like the ability to weigh up all the factors at play in a situation, including your own desires, and reach a balanced, logical, coherent conclusion. Tall order. On the minimalist version, being reasonable just means you that are responsive to reasons. It means that you are not an inanimate object, like a brick falling under the force of gravity. You can, for example, see an uncontrolled fire and decide to run away.
Critics of the very idea of mental capacity sometimes assume that the concept is based on a maximalist idea of reason; and then, understandably, doubt whether anyone can live up to that. This is a straw man. All the Mental Capacity Act 2005, for example, requires is that someone can understand, retain, and use and weigh the ‘information relevant’ to a decision. It doesn’t say all the information, or completely understand the information relevant, or that any decision must be logical and considered; and judges talk a lot more about the dangers of setting the bar for capacity too high than the dangers of setting it too low. To me, this looks a lot like a minimalist account of reason. You are reasonable if you are responsive to the reasons that are relevant in that situation (that raises the question of who gets to be the final judge of what is relevant, but that’s not about the concept of capacity, it’s about who gets to judge it).
Once again, it’s about taking a side on an issue. Being ambiguous between minimalist and maximalist accounts helps no-one. The thrust of the disability rights claim is that people with disabilities are responsive to reasons, but the law treats them as though they are not. For that blow to hit, though, it has to be against the law as it is, not against some maximalist rationality that goes beyond the law.
There is a third ambiguity tangled in these two. The ambiguity between making a decision and being able to make a decision. On occasion, it is pointed out that everyone does act irrationally sometimes. This adds nothing to the debate. Incapacity is an inability to understand and ‘use and weigh’ and so on, not a failure to do so. Failing to understand does not, by itself, mean that you lack mental capacity. Similarly, calls for reform are not based on the idea that people with disabilities always will understand and ‘use and weigh’ information. They are based on the idea that they can do those things.
Once again, there is a need to choose a place to stand. You can, of course, say that in practice the distinction between understanding and being able to understand is ignored. It’s an important point to make, but then they’re using the concept of mental capacity to criticise practice. You’re no longer criticising the concept. Or you can argue that in practice the distinction is going to cause a total mess because it will be hard to tell failing to understand from being unable to understand. I did that myself. Then, though you’re not really attacking the concept of capacity. You’re just questioning how useful it is.
So, to wrap up, there are three ambiguities: between the claims everyone is rational or everyone is irrational, between minimalist and maximalist rationality, and between making a decision and being able to make a decision. So far as I can see, the only place to stand if you both want to argue for disability rights and to hit the concept of mental capacity is for rationality, for minimalist rationality, and for capability over actuality. In other words, for the claim that people are capable of minimalist rationality. To argue from universal irrationality is absurd and self-defeating. To argue against maximalist rationality, or that everyone sometimes fails to understand or ‘use and weigh’, is to miss the concept of mental capacity entirely.
On a related note, it’s common for advocates of strong interpretations of Article 12 of the UNCRPD to tell stories in which claims for universal personhood are new. This is a historical nonsense, and as a rhetorical move, I don’t think it’s a good idea. Kant thought all human beings were capable of autonomy ‘from conception’, and Augustine clearly considered those with intellectual disabilities to be full persons. What is new is the claim that personhood entails being able to make every relevant decision yourself. I don’t think that the new claim, that personhood entails complete control over decision-making, has yet been adequately defended. For now, though, I just want to draw attention to the rhetorical move of unnecessarily claiming newness for universal personhood. Rather than stress conflict with what went before, why not emphasise continuities with the Christian and Enlightenment traditions? After all, does a wise martial artist not use their opponent’s momentum?