Rule-List Fallacy

[Brian MacWhinney]

Dear Funknetters,
     This posting is not directly about the Newmeyer analysis, which  
seemed reasonable enough to me, but rather about the issue of the rule- 
list fallacy.  Basically, my point here is that thinking of this as a  
dichotomy is useful for a first pass, but soon becomes inadequate when  
you think of actual mental processing.
     Within psycholinguistics, the interplay between lists and rules  
is the centerpiece of the debate between single and dual-route  
models.  In the dual-route account, one route is rule (or rather  
combination with the result adjusted by rule) and the other is rote  
(or lists).  Evidence for lists usually relies on the existence of  
exceptions to rules.  Evidence for rules usually relies on  
productivity for new forms.  In child language, productivity is also  
evidenced by overregularizations and other errors.  This interplay  
between combination and rote occurs on every linguistic level.
     The most powerful model of dual-route interactions sees the two  
processes as engaged in a horse race.  Both operate all the time, but  
the winner in a given case is determined by item strength and support.
    In 1986, Joe Stemberger and I provided evidence indicating that  
even regular forms such as "wanted" are occasionally produced by rote  
(or lists), since high frequency regulars are more resistant to speech  
errors phenomena then low-frequency regulars.  If all regulars were  
produced by rule, this type of frequency effect should not obtain.
    One can also describe the rule-list interplay in a single-route  
connectionist model.  However, in my opinion, such models simply  
involve recharacterizing rules as gang effects. And these models have  
to enforce special procedures to guarantee that lists can survive.  In  
the end, they just recharacterize the dual route .  So, I see no real  
way out of the idea of an interplay between processes and a horse race  
between forms.
     What does this mean for the FunkNet discussion?  Basically, it  
means that, in a given usage of a particular form by a given person at  
a given moment, one seldom knows whether rules or lists applied.  Only  
if a clear productive overgeneralization occurs, and this is very  
rare, can one know for sure that a rule or gang effect applied.  Given  
this inherent ambiguity of real data and the essentially competitive  
nature of the underlying process, only models that provide a  
fundamental role of dual-process interplay make contact with  
psychological reality.  Fortunately, by examining the numbers in large  
corpora, one can get an idea of the overall strengths of the various  
horses, but that is about the best one can do and doing that right  
takes some care.
    Given this horse race view, I find it difficult to understand how  
one can view either rules or lists as the unmarked or default case or  
suggest that there is any null hypothesis regarding this interplay.  
One can entertain opposing null hypotheses, of course, but their half- 
life would be measured in seconds.

--Brian MacWhinney