What could have been said? Alternatives and variability in pragmatic inferences

A recent influential experimental finding in pragmatics is that of scalar diversity: that different lexical items vary robustly in how likely they are to lead to scalar inference. For instance, hearers are much more likely to strengthen the meaning of some to some but not all than to infer good but not excellent from good. In this paper, we address the question of what underlies scalar diversity and identify two sources of uncertainty: uncertainty associated with the identity of relevant alternatives, and uncertainty associated with the step of excluding those alternatives. In our experiments, we make use of the Question Under Discussion to eliminate the former, and of the focus particle only to eliminate the latter kind of uncertainty. Our findings show that both manipulations make inference calculation more likely, but only when they are combined is scalar diversity reduced to a minimum. In order to quantitatively characterize the observed (reduction in) variation, this paper adopts the information theoretic measure of relative entropy.