We directly compare quantity-related inferences from scalar implicatures
and definite presuppositions to exhaustivity inferences in it-clefts for
which the theoretical literature disagrees on the inference's source --
pragmatic (like scalar implicatures), or semantic (like presuppositions).
We test English-speaking 4-to-6-year-olds and adult controls to capture the
age range during which the relevant inferences are developing. Analysis of
individual response patterns shows that if exhaustivity shares an
underlying link with another quantity-related inference at all, it is more
likely that cleft inferences and presuppositions share a common source, as
semantic theories of exhaustivity have proposed.