If we conceptualize a theory of human sentence comprehension as a combination of (1) a grammar (2) a strategy for using the rules of the grammar and (3) some architectural facilities like memory we still have a huge space of possible theories. It would be nice to narrow this class down to just those that somehow made sense in relation to the communicative function sentence-comprehension often serves.
This talk examines a smaller class of comprehension theories that strive to finish parsing as soon as possible. These theories would be "rational'' on a view of the comprehender as doing his or her best to understand what the speaker means. I shall argue that they correctly derive well-known garden pathing phenomena along with the puzzling Local Coherence effects studied by Tabor, Galantuccia and Richardson (2004). Time permitting, I will discuss the relationship between this class of theories and the Entropy Reduction Hypothesis revived in Hale (2006).