Paulina Sliwa (2015) argues that knowing why p is necessary and sufficient for understanding why p. She tries to rebut recent attacks against the necessity and sufficiency claims, and explains the gradability of understanding why in terms of knowledge. I argue that her attempts do not succeed, but I indicate more promising ways to defend reductionism about understanding why throughout the discussion.

Cognitive-linguistic theories commonly model speakers’ grammatical knowledge as a network of constructions related by a variety of associative links. The present study proposes that structural priming can provide psycholinguistic evidence of such links, and crucially, that the method can be extended to non-alternating constructions. In a comprehension priming experiment using the “maze” variant of self-paced reading, English caused-motion sentences were found to have an inhibitory effect by slowing down participants’ subsequent processing of resultatives, and vice versa, providing evidence that speakers (...) store distinct but related representations for the constructions. Priming effects of a similar magnitude emerged in both directions, suggesting that the constructions are bidirectionally related, while not supporting previous claims about a metaphorical asymmetry between the patterns. Moreover, priming was only marginally affected when prime and target contained the same rather than different verbs, demonstrating that cross-constructional priming in comprehension can be observed in the absence of a “lexical boost”. The results raise questions for follow-up research on the role of inhibition in the grammatical network and the extension of structural priming to other types of constructional links. (shrink)