It’s in the Attitude

In “semantic vagueness in Psychiatric Nosology,” Nicholas Tilmes offers a conditional claim for further consideration (Tilmes, 2022). The conditional is that “if psychiatric vagueness exists, there is reason to think that some cases of it are at least partially semantic.” From this, some conclusions worth investigating follow. In this brief commentary I will set out a question Tilmes introduces by, like him, drawing on a paper by Miriam Schoenfield, which also examines vagueness as semantic, epistemic or ontic though she draws a contrasting conclusion for her subject matter: moral judgment (Schoenfield, 2016). Highlighting a supposed contrast between semantic and ontic vagueness will also highlight an issue for psychiatric diagnosis. (Limits on space preclude a parallel argument about epistemic vagueness.)

Tilmes illustrates psychiatric vagueness by the application of the Sorites paradox of the heap to cases such as diagnosis of dementia based on memory loss where “there does not seem to be a non-arbitrary number of memories that must be lost before a diagnosis is warranted.” If diagnosis like this is vague, what is the source of the vagueness?

The contrast between semantic, epistemic and ontic accounts of vagueness apparently depends— roughly!—on whether it reflects a feature merely of language use, or of ignorance or an indeterminism in worldly phenomena themselves. (I will return briefly to how natural these contrasts are.)

Tilmes characterizes semantic vagueness as arising “from disagreements between linguistic communities about the boundaries of vague predicates.” Further work is needed to show this is not the result of disagreement in the face of ontic vagueness, of course. Schoenfield gives the example of an apple developed in 1924 by crossing Red Delicious and Cox’s Orange Pippin varieties to yield an orangey red result called “Kidd’s Orange Red.”

Suppose I give you such an apple. I let you touch it, look at it, and measure its reflectance properties. None of this investigation, however, settles for you the question of whether the apple is red. But note that, even if you are a great apple connoisseur, the question of whether Kidd’s apples are red will probably not keep you up at night.

(Schoenfield, 2016: 257)

This, intuitively, fits a semantic account of vagueness that she characterizes thus:

we just haven’t gotten around to settling on a precise cut-off point for “red.” Many candidate cut-off points would be acceptable and, if only we spoke more precisely, our word “red” would refer to a precise property.

(Schoenfield, 2016, p. 258).

Suppose, as Tilmes suggests, that some element of psychiatric diagnostic vagueness is semantic in origin, what follows? Tilmes suggests both that “the boundaries of psychiatric conditions may not be entirely mind independent” but, positively, that “dwelling on differences in how communities apply psychiatric terms might enable clinicians to make more informed diagnoses in practice.” But he then raises the question as to whether, instead, “we should solely gather behavioral, experiential, and neural data and not consult linguists when studying the extension of psychiatric conditions.” And relating his paper to Schoenfield’s, he asks: “can differences in the ways in which linguistic communities describe psychiatric conditions affect whether it is appropriate to render a diagnosis in borderline cases?”

I am not certain how he answers this question given ambiguity as to the meaning of “appropriate” (e.g., true/valid versus justified to a particular community). But to get a sense of this issue it is worth sketching one element of Schoenfield’s dialectic. She too offers a Sorites based example of vagueness:

Cheryl is pregnant. She and her partner suddenly realize that, if the pregnancy is carried to term, they’ll have to skip a much-anticipated vacation that they had long ago planned with a group of friends. They don’t think that skipping the vacation would have a significantly negative impact on their lives. But, all things considered, they’d prefer that the fetus not be born. It is permissible to abort after one day for these reasons. It is not permissible to abort after nine months for these reasons. Is it permissible to abort at 150 days? 151? 151.5? Plausibly...