Levels of Explanation and Scalar Implicature

This week's reading hearkened me back to Carnie's levels of explanation.  Both articles contained case studies on children's abilities to interpret Gricean implicature, specifically with scalar implicatures.  Early researchers on this topic believed that young children's inability to draw the expected implicatures from scalar implicature, one example being that 'some' implies 'not all', meant that children at around 3-4 years of age had not yet acquired implication abilities.  This conclusion was a strong observationally-adequate explanation.  If children were not able to infer these scalar implicatures, it was likely that they just lacked the capacity to implicate.

A challenge to that neat explanation came in the form of contemporary experiments that showed that children could properly interpret numerical quantifiers, but not quantifiers such as 'some' and 'all'.  This poses a problem because we would assume that children would acquire all quantifiers at around the same time, because quantifiers all modify objects in a similar way.  But researchers were showing that children could infer that “five of x” was different from “one of x”, even if they only knew what “one of x” meant.  The question was left: if the lack of implicature is why these children respond to scalar implicature in pragmatic quantifiers differently from adults, then why is there no similar issue with numerical quantifiers?

Here Carnie comes in.  The original hypothesis, I would argue, was not explanatorily adequate, or it could not "account for observed real-world data and native speaker judgments and offer an explanation for the facts of language acquisition."  It directly violated our intuition that children should acquire an understanding of all quantifiers in a similar way.  The new theories proposed by these researchers, I believe, are explanatorily adequate.  Barner's proposition that it is the children's lack of knowledge of relevant alternatives that prevents them from making the implicature makes a lot of sense.  Intuitively, it is obvious--how would a child know that "some" implies "not all", if they are not familiar with the concept of "not all"?

These readings left me curious as to how children do acquire the capacity for pragmatic implication.  Does a child need to have many experiences in which they learn that "Some of x does y" implies that "Not all of x does y"?  I am not sure how it would be possible to learn implicature without mass exposure to implicature usage in concrete settings.  When someone says, “Some of x does y”, they almost never qualify that statement by following it with, “But not all of x does y”.  This might mean that children need to interact with the world--and have the outside knowledge that “Not all of x does y”--to gain that kind of implicature understanding.  Lastly, I am curious how social weighting might play a role in how children acquire the ability to conversationally implicate.