Friday, May 30, 2014

Baker's Paradox I: Bigger than you think

After a long hiatus (without any particularly good excuse), I come back to child language.  Let’s jump right into it. 

In a classic paper, C. L. Baker lays out what has become known as the Projection Problem: “What is the functional relation that exists between an arbitrary human being’s early linguistic experience (his ‘primary linguistic data’) and his resulting adult intuitions?”. Of a range of examples Baker considers, the dative constructions in English are most prominent:

(a)     John told a story to Bill.
John told Bill a story.
(b)   John promised a car to Bill.
        John promised Bill a car.
(c)   John donated a painting to the museum/them.
*John donated the museum/them a painting.

Baker’s Paradox concerns the acquisition of negative exceptions: How does the learner know that the double object construction (c) is not available to verbs such as donate while they encounter plenty of positive instances such as (a-b)? Since negative evidence is generally not available, the child cannot rely on direct negative feedback. At the same time, the child cannot assume unattested linguistic forms to be ungrammatical in general, for that would rule out the productive and infinite use of language.

The 1980s saw a large body of work on Baker’s Paradox. The most comprehensive treatment is probably Steve Pinker’s 1989 Learnability and Cognition. It reviews all the major proposals available at the time, many of which have resurfaced in recent years. (They are problematic now as were then.) But I will only turn to the acquisition of the dative constructions in a later post: the issue at hand is much more general and significant, which I illustrate by quoting from some illustrious scholars:

The fact of grammar, a universal trait of language, is simply a generalized expression of the feeling that analogous concepts and relations are most conveniently symbolized in analogous forms. Were a language ever completely grammatical, it would be a perfect engine of conceptual expression. Unfortunately, or luckily, no language is tyrannically consistent. All grammars leak. (Sapir 1928)

Clearly, we must design our linguistic  theory in such a way that the existence of exceptions does not prevent the systematic formulation of those regularities that remain. (Chomsky & Halle 1968)

Viewed against the reality of what a particular person may have inside his head, core grammar is an idealization. From another point of view, what a particular person has inside his head is an artifact resulting from the interplay of many idiosyncratic factors, as contrasted with the most significant reality of UG (an element of shared biological endowment) and the core grammar (one of the systems derived by fixing the parameters of UG in one of the permitted ways. (Chomsky 1981)

But how are we to know which phenomena belong to the core and which to the periphery? The literature offers no principled criteria for distinguishing the two, despite the obvious danger that without such criteria, the distinction seems both arbitrary and subjective. The bifurcation hence places the field at serious risk of developing a theory of language that is either vacuous or else rife with analyses that are either insufficiently general or otherwise empirically flawed. There is the further danger that grammatical theories developed on the basis of ``core'' phenomena may be falsified only by examining data from the periphery--data that falls outside the domain of active inquiry. (Sag 2010)

That language has exceptions is plain enough for everyone to see. Baker’s Paradox, like the past tense of English, is an easily digestible and well researched example. But how to put exceptions in their proper place has been a controversial and divisive issue. No, I’m not talking about how the linguist may distinguish or record rules and exceptions. Perhaps rules are “in the syntax” and exceptions are “in the lexicon”, perhaps productive affixes are “outer” and unproductive affixes are “inner” in the morphological structure, perhaps the metrical stress of English is described by a few parameter values, with the unruly words marked with diacritics. These may well be the right theoretical analysis, but morphemes, words and constructions do not announce if they belong to the core or periphery (or syntax vs. lexicon, or inner vs. outer): that's for the child to figure out.

A possible route is to abandon the core vs. periphery distinction. Indeed, I think it is the same long tradition that runs from Lakoff’s irregularity in syntax to Maurice Gross’s taxonomy of French verbs, from Construction Grammar to Simpler Syntax, from Martine Braine's Pivot grammar to Usage based learning. Grammar is a collection of language and construction specific rules/patterns/analogies and that’s that. 

I don’t find this approach promising. First and foremost, there are developmental findings from child language that show, convincingly on my view, the presence of an overarching and abstract grammar, part of which looks like a P&P system. Second, we know how hard it is to write grammars or to statistically induce them from the data; see here for my own take.  I won’t dwell on these points. The more pressing issue is for those of us who believe in the core grammar. We need to articulate a theory of exceptions, with which the learner can identify them as such, memorize them if necessary, so the acquisition of the core grammar can proceed without interference. We should never give up on better treatments of exceptions—some are probably only apparent—but we can no longer pretend as if they do not exist. Think about how much has been written on parameter setting as if the data is clean (and the crucial setting of the stress parameters requires words like Winnipesaukee). In other words, let's go back to the 1980s because we owe Ivan Sag an answer. 

I will discuss these issues in the next few posts.  To preview some of the main points:

1. We need inductive learning in addition to parameter setting. 
2. We need an evaluation procedure in the sense of LSLT/Aspects but connects to the third factor in empirically interesting ways. 
3. We need to reconceptualize how to solve Baker’s paradox, and we need to do it with real acquisition data.


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