hey. i guess the issue comes down to this:

is there one standard whereby anyone who deviates from that standard is 'defective' or 'malfunctioning' or 'disordered' or 'abnormal'?

you think: yes and i think: no.

if there is one standard then i get to ask:

what makes it the case that there is this standard?
or in virtue of what is there this standard?
or what makes it true that there is this standard?

(i'm tempted to say the burden of proof is on you for positing this standard but seeing as most people seem to agree their is one i guess the burden of proof is on me for offering such a counter-intuitive view).

i'll try and sway your intuitions...

wakefield's argument (for evolutionary function / malfunction) goes like this:

1) It is a-priori (true by virtue of the meaning of the term 'mentally disordered') that there is an inner malfunction.
2) A-priori (for all we know from the meaning of the term) the relevant process for fixing the function / malfunction could be god...
3) A-posteriori (scientists discovered) that the relevant process for fixing the function / malfunction is evolution by natural selection...
________
Mental disorders are evolutionary malfunctions.

Murphy has criticised premise 3 by drawing our attention to three different notions of function that are employed by the life sciences. While some theorists have argued that they are just different sorts of the same over-arching thing they appear to be quite different in the sense that they judge different things to be functions and malfunctions. There is nothing in science to show us that we should adopt one of these notions of function over the others... None of them capture our intuitive judgements as to who is and is not mentally disordered.

I'm thinking that 'function' (and malfunction) is a RELATION. If something is malfunctioning we need to ask 'malfunctioning with respect to what'? This is the idea that there needs to be some standard where something either conforms to it (functions) or does not conform to it (malfunctions). I'm not seeing an objective standard here, however...

One could say that the best scientific theory will offer us a model of human biological, psychological, and social functioning. Thus, if people conform to this they are functioning and if they don't conform to this they are malfunctioning. The trouble is determining which of the facts about people get to be represented in the model. Intuitively we don't want to build 'brown hair' into the model (whereby other hair colours are malfunctions). Intuitively... Well... Do we build male or male and female or 10 different sexes into the model... What facts about the world could decide this?

There is a fable about a person who wanted to make the most accurate map he could possibly make. It had a 1:1 ratio and he couldn't roll it out for fear of upsetting the farmers.

Not quite sure how that relates... I guess I think that looking at the world... it is far from obvious whether something constitutes a function or a malfunction. People have their intuitions and those intuitions seem to be built into the scientific models. Science does this when it attempts to model normal functioning (in some respect) then explain mental disorder as a breakdown in the model. Seems to me that one could alternatively begin by attempting to model mental disorder (in some respect) then explain normal human functioning as a breakdown in the model. Which choice we make seems arbitrary...

Of course we are most interested in majorities (women successfully campaigned to get F regarded as an alternative way of being whereas other sexes most probably won't be successful because there are so few of them). But surely the majority can be diseased (e.g., infected with parasites) and surely the majority can malfunction too...

I guess I just fail to see what facts about the world make it the case that there is a 'right' and a 'wrong' way to model the world with respect to whether somthing is a function (built into the model) or a malfunction (a deviation from it). We have a variety of models... And their determinations about the world often disagree quite severely (hence controversy over whether addiction is rational or irrational where the determination is dependent on the assumptions of the model).

depending on the assumptions of the model. in other words... depending on the intuitive judgements that people made BEFORE doing science... in other words... judgements formed by social convention (the way social practices currently are) rather than scientific considerations (where their judgements are informed by society-independent facts about the world).