Deconstructing Ontological Vagueness

I will here present a number of problems concerning the idea that there is ontological vagueness, and the related claim that appeal to this idea can help solve some vagueness-related problems. A theme underlying the discussion will be the distinction between vagueness specifically and indeterminacy more generally (and, relatedly, the distinction between ontological vagueness and ontological indeterminacy). Even if the world is somehow ontologically indeterminate it by no means follows that it is, properly speaking, ontologically vague.²

I Vagueness And Indeterminacy

The debate which I will focus on here concerns the nature of the indeterminacy with which vagueness is associated. Some - presumably most - hold that vagueness is a matter of semantic indeterminacy. These people would hold that if, say, a singular term is vague, then there exist several objects such that the term is indeterminate in reference as between these objects.³ Call these objects candidate-referents of the term. Others would regard vagueness as, at least sometimes, a matter of ontological indeterminacy. These people hold that (sometimes) if a singular term is vague, then it refers to an object that is itself vague. Vague singular terms are 'indeterminate in reference,' not in that it is indeterminate exactly what they refer to, but in that the objects they refer to are themselves indeterminate.⁴ It is worth keeping in mind that even given an answer to the question of what type of indeterminacy vagueness is associated with, many other questions in the vicinity are left unanswered.

A preliminary point is this. There are many varieties of semantic indeterminacy and many varieties of ontological indeterminacy. If vagueness is associated with semantic indeterminacy, there is the further question of what kind of semantic indeterminacy it is associated with. If vagueness is associated with ontological indeterminacy, there is the further question of what kind of ontological indeterminacy it is associated with.

Consider first some varieties of semantic indeterminacy. (i) Quinean inscrutability of reference: the sort of indeterminacy of reference purportedly established by Quinean 'gavagai' arguments - see Quine's famous (1960). The facts that determine reference fail to determine whether 'gavagai' is true of rabbits, or undetached rabbit parts, or timeslices of rabbits, or… (ii) We know from modern physics that nothing satisfies all the claims that Newtonian physics makes about 'mass.' Instead there exist two different possible referents of Newtonian 'mass,' proper mass and relativistic mass, both of which approximately satisfy the claims Newtonian physics makes about 'mass.' It seems wrong to say that 'mass' as it occurs in Newtonian physics does not refer. Rather, 'mass' as used in Newton is indeterminate in reference as between proper mass and relativistic mass.⁵ (iii) Third, something for which we can use the label semantic indecision or the label incompleteness of meaning. (Both labels have been used. Maybe the former label is preferable since it carries less theoretical baggage.) Consider a predicate 'nice1' introduced by incomplete stipulations

n is not nice₁ if n<13

n is nice₁ if n>15.

(Fine, 1975, 120)

The predicate 'nice₁' is partially defined. We have been somewhat semantically indecisive w.r.t. 'nice₁.' Maybe it is right to say that its meaning is incomplete. (iv) It is possible to hold that the semantic indeterminacy associated with vagueness is sui generis.

Given that vagueness is associated with some kind of semantic indeterminacy, one can hold either that it is a sui generis kind of semantic indeterminacy, or that it is one instance of a more general semantic indeterminacy phenomenon. Some theorists of vagueness would want to say that vagueness just is semantic indeterminacy. Some theorists would want to say that vagueness is an instance of semantic indecision.

In distinguishing between (i) through (iv), I do not mean to assert that these are in the end different varieties of semantic indeterminacy. Maybe some collapse into each other. But prima facie they are distinct. The reason that 'nice₁' is semantically indeterminate (partial definition) is different from the reason that 'mass' is semantically indeterminate ('mass' gets its reference determined by a false theory). Intuitively, we have not said enough to ensure that 'nice...