The Journal of Philosophy

Volume 117, Issue 11/12, November/December 2020

John MacFarlane
Pages 643-667

Indeterminacy as Indecision, Lecture III: Indeterminacy as Indecision

This lecture presents my own solution to the problem posed in Lecture I. Instead of a new theory of speech acts, it offers a new theory of the contents expressed by vague assertions, along the lines of the plan expressivism Allan Gibbard has advocated for normative language. On this view, the mental states we express in uttering vague sentences have a dual direction of fit: they jointly constrain the doxastic possibilities we recognize and our practical plans about how to draw boundaries. With this story in hand, I reconsider some of the traditional topics connected with vagueness: bivalence, the sorites paradox, higher-order vagueness, and the nature of vague thought. I conclude by arguing that the expressivist account can explain, as its rivals cannot, what makes vague language useful.