Examining Assumptions about Vagueness

Ithank the commenters for their insightful remarks, from which I have learned much. In my article, I sought to explain psychiatric vagueness, which arises in borderline cases where there is no fact of the matter as to whether a diagnosis rightly can be said to apply.¹ I argued “if psychiatric vagueness exists, then some of it is at least partially semantic” (Tilmes, 2022). A semantic account holds that vague utterances express different propositions since small gaps in how linguistic communities apply terms modify their referents, making their precise extension indeterminate.² On my view, this best accommodates intuitions about the nature of conditions and explains historical changes in the application of psychiatric terms. A semantic account implies that we can sometimes settle diagnostic questions by attending to linguistic data and that some vagueness will remain so long as differences in language use do. I also argued that solely epistemic and ontic accounts—which attribute vagueness to ignorance and the world—come to implausible conclusions about psychiatric vagueness and fail to help us navigate it, respectively.

It is worth clarifying my position here. First, I do not claim that all psychiatric vagueness is semantic, but only that some cases of it at least partially are. “This leaves open the possibility of vagueness having multiple sources” (Tilmes, 2022) and does not require abandoning all non-linguistic considerations. Indeed, thinking that the borders of psychiatric conditions are affected by language need not entail rejecting concepts of etiology or kinds altogether, just as thinking that it is indeterminate when red turns to orange does not entail rejecting the notion that color is shaped by wavelengths of light. Second, I do not argue that diagnostic manuals or theories of psychiatric kinds necessarily reflect assumptions about vagueness, but that each account of vagueness lends itself more to certain approaches. For instance, if understanding psychiatric vagueness as a problem of language commits one to anti-realism, adopting a primarily semantic approach may give one reason to reject realist theories of psychiatry.

Dan Stein contends that we should “side-step the Sorites paradox, and its notion that our language categories are in any way related to precise formulation in terms such as n and n + 1” (Stein, 2022). For instance, he notes that while the Diagnostic and Statistical Manual of Mental Disorders (DSM) requires symptoms of generalized anxiety disorder to last 6 months, the International Classification of Diseases, 11th edition, only stipulates that they last for several months. However, this does not solve the problem of vagueness so much as displace it. Whatever a clinician interprets the lower or upper bound of “several months” to be, they must eventually ask: why should it not be a day, a minute, a second longer or shorter? Indeterminate cases remain at either end of fuzzy thresholds.

Stein further states that “our categories are graded, and that there are more and less typical exemplars of any particular category” (Stein, 2022). As an example, he posits a spectrum of typical and atypical disorders, where the former, like post-traumatic stress disorder, are imposed by others and the latter, like alcohol use disorder, involve some responsibility on the part of the individual. It is unclear why this implicates a semantic account. First, exemplars do not dispel vagueness; after all, firetruck red exists, but we still must say when it turns into orange. Second, the contrasts Stein cites, like that between post-traumatic stress disorder and alcohol use disorder, are too large. The vagueness I am interested in bears on smaller gaps, like whether n, n + 1, n + 2, and so on drinks warrant intervention. Third, Stein’s spectrum hinges on moral vagueness (whether one is morally responsible for drinking) while I am concerned with psychiatric vagueness (whether a diagnosis rightly applies). The two ought not be conflated, for reasons I discuss later.

Finally, Stein argues that study of vagueness is misplaced because conditions can “be conceptualized as more atypical or as soft natural kinds; messier entities, with fuzzier boundaries” (Stein, 2022). However, this is not mutually exclusive with a semantic account, which “accommodates the intuition that disorders lack sharp cutoffs while leaving...