Commitment sharing as crucial step toward a developmentally plausible speech act theory?

From the point of view of cognitive development, the present paper by Bart Geurts is highly relevant, welcome and timely. It speaks to a fundamental puzzle in developmental pragmatics that used to be seen as such, then was considered to be resolved by many researchers, but may return nowadays with its full puzzling force. The puzzle in question is the following: on broadly Gricean accounts, how should young children ever be able to start communicating, given that even basic conversation requires heavy cognitive machinery of recursive higher-order mindreading, and given that young children appear not to be such higher-order mindreaders yet? (Which, in fact, as much research suggests, they may actually become over development as a consequence rather than as a precursor of language acquisition.) This puzzle has been most clearly described by Richard Breheny in 2006 in the form of a trilemma (Breheny 2006): (i) Verbal communication requires higher-order intentionality (that is, a propositional attitude “Theory of Mind” – as it is often called in developmental psychology – that involves concepts of belief, etc.) (ii) Young children before age 4 do not yet have such a Theory of Mind; yet (iii) Young children clearly do engage in verbal communication.