Neil Pickering has recently published a nice paper on the derivation of the concept of 'mental disorder' from that of 'physical disorder'. A family resemblance (perhaps his own?), and a secondary sense (mine), account of how this works are evaluated. (One rather nice if odd thing for me is that Pickering argues that my secondary sense account is more original than I thought it was - since I'd always assumed I was merely elaborating on T S Champlin's argument in To Mental Illness via a Rhyme for the Eye.) The question is asked: What makes for the validity of an extension of a concept from its primary domain to the new domain?
Pickering does a good job of undermining certain essentialist prejudices regarding what makes for the validity of a conceptual extension. The family resemblance account (that mental and physical disorders may share various features in common but none essentially) is shown to satisfy a certain somewhat relaxed understanding of what demands for determination (distinguishing members from non-members of a set) and coherence (inner unity of the set) impose on the acceptability of proposed extensions. The secondary sense account is shown to not meet these - but this is perhaps not surprising since the whole idea of secondary sense (and of Lakoff and Johnson's 'conceptual metaphors') is that our uses of such terms are governed by the unprincipled associative whims (as it were) of our culture-bound CNSs.
What all of this makes me think, though, is how rather strange it is that so many (well, a few) philosophers (like me) take themselves to be called to provide 'accounts' of what mental disorder consists in - and how odd it is really that it isn't just obvious whether the concept of 'mental illness' is a prototypical, family resemblance, secondary sense, subtype of physical illness, natural-(dys)function-explicable, etc. concept. Is it really the case that the language-games of mental disorder ascription are that opaque - that we must all be rather left merely gesturing from afar at what it is we are doing when we say of someone, as we all sometimes do, that they are or are not mentally disordered?
I have (groan) another (somewhat deflationary) theory of all this. Which is that there probably just isn't really any such thing as 'the' language game of 'mental disorder'. Rather there are a range of different aspirations, phantasies, habits, understandings, cultural histories, departmental quirks, etc., underlying talk of 'mental disorder', 'mental disease', 'emotional disturbance', etc. Different presentations of different kinds of patients pull us this way and that both within and between the deployment of these notions; the seas and shores of language shift a little between regions and nations, or over historical times, or between the clinic and the academy.
So perhaps there is not really any determinate language-game being played out by different people with terms like 'mental disease', but a set of overlapping and ill-defined moves in conceptual space are nevertheless constantly being made. It's all a bit of a mess, but we get by. The philosopher however strives for tidiness - and perhaps even more so wishes that the tidiness is already there waiting to be discovered. So they project a conceptual structure underneath all this mess, and generate accounts which propose what the language game is 'really' all about.
Reading Kuusela's lovely Struggle against Dogmatism gives me another idea of how to proceed. Which is that, rather than trying to determine 'the' logical structure of 'our' (whose?) concepts, we could instead steer our philosophy to two other ends: a) noticing when muddles arise due to the un-noticed using of terms in different senses, or due to prejudices about what 'must' be meant by the terms in use, and b) articulating clear stipulative paradigms for the use of such terms for the purposes of clarification. Whether that will ever be enough to dent the wish or need or phantasy of philosophers to take themselves to be uncovering deep facts about existence is however another matter.