• Dementia
• Competence/incompetence

As I sympathise with the main thesis of Tom Buller's article1—the thesis that if we are prepared to accept advance directives in the context of treatment then we should also accept them in the context of research—I shall focus my commentary on a premise of his argument which he accepts for the sake of argument: the principle of precedent autonomy. In short, the principle claims that it is the right of a competent individual to make decisions for a later time once competence has been lost. Whether we accept it or not crucially hinges on how we assess the relation between critical and experiential interests. Buller writes: “The authority and legitimacy of critical interests are not negated by contradictory experiential interests. Accordingly, to respect the wishes of the now incompetent patient is to override a legitimate exercise of the individual's autonomy”. I shall argue that the first sentence does not hold true sans phrase. Rather, it needs some specification. Different scenarios can be distinguished:

1. There may be a simultaneous contradiction between critical and experiential interests. Leading a healthy life may be central to my conception of a good life, but while having a critical interest in living healthily I may at the same time feel a pressing need to smoke a cigarette. In this case the authority of critical interests is left untouched by contravening experiential interests because, as Buller rightly writes, ‘this is precisely their function’: critical interests are (in part) defined as interests whose function is to control experiential interests that run contrary to our present critical interests.

2. There may, however, also be a non-simultaneous contradiction between critical and experiential interests: it may occur that while a person loses her ability to have critical interests she still has experiential interests, and these latter interests may …