Unthinkable Syndromes. Paradoxa of Relevance and Constraints on Diagnostic Categories

Bodies of collective knowledge evolve through individual
action, like all products that have a use. They also can be
evaluated from the engineer's optimizing design perspective.
But can individual participants in their making
recognize local optimality? Can they work to realize it? Are
they unable to act seriosly in a way that would ensure
acquisition of a certain suboptimal design feature?
One might hope for a simple answer: appeal to innate
constraints on the form of categorization. But such constraints
cannot wholly pre-empt the need for individual
checks and thus for agency. The use of categorial
schemes engages facts about the world that do not leap to
the eye. They are unlike syntactic or phonological constraints
of language, or edge-and orientation-detection
algorithms of visual perception.
What we should thus be looking for will be modest:
constraints, innate or otherwise, that rule out the choice of
categorial schemes which are clearly suboptimal and that
are, in principle, open to agents' instant observation. We
look to a limited if important domain of systematic knowledge:
medical diagnostic knowledge.