OF THE FORTY-FIRST ANNUAL MEETING OF THE BERKELEY LINGUISTICS SOCIETY February 7-8 , 2015 General Session Special Session Fieldwork Methodology

There is a well-known preference for disjunctions XorY to be construed so that X and Y are semantically disjoint. However, there are two felicitous usage patterns in which the speaker violates this preference in part to convey information about the language itself. First, disjunctions of terms in a one-way semantic inclusion relation, such as boat or canoe, can form part of a speaker strategy to manage lexical uncertainty surrounding the two terms, or block unwanted implicatures that the listener might draw from the general term alone. Second, disjunctions of synonymous terms like wine lover or oenophile can be used to convey definitional information. We explore both of these uses, relying on corpora to obtain a fuller picture of their motivations and their effects on the listener. In addition, we show how both these uses are predicted by a standard semantics for disjunction and a recursive probabilistic model of communication in which speakers and listeners simultaneously exchange information about the world and about the language they are using. We also use the model to begin to formally characterize the pragmatics of implicature cancelation or blocking. 1 Communicating in Language about Language Natural languages are neither fixed across time nor identically reproduced in all speakers, but rather continually renegotiated during interactions (Clark 1997). Discourse participants accommodate to each other’s usage patterns (Giles et al. 1991), form temporary lexical pacts to facilitate communication (Clark & Wilkes-Gibbs 1986; Brennan & Clark 1996), and instruct each other about their linguistic views. Some of this communication in language about language is direct, as with explicit definitions like ‘oenophile’ means ‘wine lover’, but much of it arrives via secondary pragmatic inferences, as when X such as Y conveys that X subsumes Y (Hearst 1992; Snow et al. 2005). Disjunction supports what appear to be opposing inferences about language. On the one hand, XorY tends to convey that the meanings of X and Y are presumed to be disjoint (Hurford 1974), because the speaker holds such a view of the lexicon or is worried that the listener might. This pressure to exclusivize is robust enough to overcome even seemingly non-negotiable aspects of the lexicon; a medical webpage warns “If you still have symptoms or severe blockage in your arteries, you may need angioplasty or surgery”, sending a clear signal that angioplasty and surgery are distinct options. Its continuation presupposes just that: “Having one of these procedures may save your leg”. The disjunction might seem to ∗For help with the data and ideas, we thank Arto Anttila, James Collins, Ashwini Deo, Itamar Francez, Kumiko Fukumora, Larry Horn, Justine Kao, Dan Lassiter, Natalia Roudakova, Rob Voigt, and Eva Wittenberg, as well as audiences at the 2015 LSA Annual Meeting and ESSLLI 2014. This research was supported in part by NSF IIS 1159679 and ONR N00014-13-1-0287 (CP), and an Alfred P. Sloan Foundation Research Fellowship and a Fellowship at the Center for Advanced Study in the Behavioral Sciences (RL).