The case for comparability

We argue that all gradable expressions in natural language obey a principle that we call Comparability: if x and y are both F to some degree, then either x is at least as F as y or y is at least as F as x. This principle has been widely rejected among philosophers, especially by ethicists, and its falsity has been claimed to have important normative implications. We argue that Comparability is needed to explain the goodness of several patterns of inference that seem manifestly valid. We reply to some influential arguments against Comparability, raise and reject some new arguments, and draw out some surprising implications of Comparability for debates concerning preference and credence. 1 The thesis of comparability Our topic is the logic of comparative constructions: paradigmatically, the comparative forms of adjectives (‘F-er’ or ‘more F’) and the equative form (‘[at least] as F as’). ∗Thanks to Johann Frick, Jeremy Goodman, Ben Holguin, Ankit Kansal, Harvey Lederman, Ofra Magidor, Matt Mandelkern, Ralph Wedgwood, Alexis Wellwood, Timothy Williamson, Juhani YliVakkuri, and Snow Zhang.