GennariandMacDonald(2009) presentedevidence that reading times in compre-hension are influenced by the likelihoodof a speaker choosing a particular struc-ture in production. It’s an important andinteresting paper. From this they pro-pose the PDC (Production DistributionComprehension): choices made to easeplanning in production give rise to dis-tributional patterns in the input, whichin turn influence comprehension. Thepresent paper suggests maybe everything(language production, acquisition, pars-ing, and language typology) works thisway and seems to imply that there-fore we might not need abstract syntac-tic representations, recursion, a languageacquisition device, etc., at least not toexplain processing difficulty. Maybe, butwe might want more evidence. In addi-tion to the subject- vs. object-relativeclausedistinction thatmotivated the PDC,a second case is discussed in the cur-rent paper: modifiers that may attachlow or high. But the argumentation onlyshows that a production account is inprinciple possible, it doesn’t say why it’sany better than available comprehensionaccounts.PDC is usually discussed as a “view” or“perspective.” But when the author sug-gests it’s mechanistic, it sounds more likean empirical claim. If it is an empiricalclaim, then one might want to know howdistributional patterns are discovered inthe input, how general they are, how theyarestored, andhow they areutilized.Afterall, on the PDC model, that’s where all theaction is, at least for the comprehensionsystem. It might also be germane to fig-ure out whether the statistics are gatheredseparately for different speakers, differentdialects, different registers. Also, it mightbe good to provide evidence that it IS thestatistics themselves that guide expecta-tions in comprehension, and not implicitknowledge of how the production systemworks.As for the PDC perspective, let’sendorseit.Let’s lookforproduction-basedexplanations, and any other explanationswe can construct, if they are preciseenough to makepredictions.Does the PDC make predictions? Itmight if speakerscansay what they please.Butinfactthegrammarofthelanguagewilldictatewhatconstitutesaphrase,whatorder is permitted or required, whetherellipsis is possible, and so forth. And thegrammar demonstrably is NOT just thesummation of past favored productionchoices but, in addition to whatever con-straintsacquisitionorcomprehensionmayimpose,conventionandhistoricalaccidentalso come into play, and these various fac-tors interact in complex ways. So, at best,PDC applies when the grammar offersmore than one option for the same mes-sage. To take a well-known example, insentences containing adativeverb,DoubleObject structures (DO) and PrepositionalObject structures (PO) are largely syn-onymous. Maybe in such cases principleslike Easy First apply. Although Easy Firstis not well-defined, clearly on any ten-able version of it, phrases already “given”in discourse will count as “easy.” So theprediction is that given should appearbefore new, listeners should store thesestatistics, and comprehenders should findthese structures easier when given appearsbefore new. So there is a prediction. Theproblem in this case, however, concernsthe facts. For DO, the prediction appearsto be correct. But for PO, it is not (Cliftonand Frazier, 2004; Brown et al., 2012).What should we conclude from this? ThatPDC is confirmed (by DO structures)?That PDC is disconfirmed (by PO struc-tures)? That in precisely the case of inter-est,wherethegrammarpermitsmorethanone option, whatever is going on is morecomplex than PDC countenances?Let’s takeanother example. Perhapsthedative alternation is misleading for somereason.Take extraposition from subject (1b)andfromobject(2b).Apparentlywecouldexplaintheeaseof(1b)with“EasyFirst”—the most important of the three core pro-duction planning principles since “Planreuse/priming” will depend on context,and Reduce interference will depend onlexical choices. But “Easy First” wouldseem to predict no advantage for extra-position from object (2b) since the objectis last regardless of whether the object isextraposed, as in (2b), or not extraposed(2a). Nevertheless, intuitively, and in pilotdata of Emily Westland (2012), (2b) ismarkedly better than (2a). Like the dativealternation example, this suggests a PDCapproachmaybea bittoo simple.(1) a. ThatMaxleft early bothered me.b. It bothered me that Max left early.(Extraposition fromsubject)(2) a. Ihated that Maxleft early.b. I hated it that Max left early.(Extraposition fromobject)Let’s consider another example. Takethe repeatedly demonstrated findingthat speakers will include optional con-stituents (e.g., the complementizer