One place where the thorny problems of linguistic theory become most obvious and demand the most determined engagement is in the area of child language acquisition. (The other, I think, is language variation and change, unless I just say that because these are what I find the most interesting.)
Take the concept of language structure. The belief that language has structure is, naturally, fundamental to the discipline of linguistics. But it is possible to understand this in radically different ways.
According to Hirsh-Pasek and Golinkoff in their book, Origins of Grammar, theorising about child language is generally done according to one of two broad approaches, which they characterise as “outside-in” versus “inside-out”. “Outside-in” includes social-interactional theories and cognitive theories; “inside-out” includes the various permutations of nativism.
One of these approaches, they say, “contends that language structure exists outside the child, in the environment.” If I didn’t tell you any more, would you be able to say which of the two options – ‘interactionist’ or ‘nativist’ – was being described here?
In fact, HP&G are referring to social-interactional/cognitive theories as believing that language structure exists outside the child (nativist theories rely instead on the innate language-specific knowledge).
Now it is quite possible that some theorists on the interactionist side do believe in language structure as having some sort of real-if-‘abstract’, independent existence. This would betray itself by, for example, the use of terms like “finding” or “discovering” things like “units” (or the boundaries between units) such as segments, morphemes, phrases, clauses in the ambient language. Such interactionists would then share with nativists the view that (spoken) language embodies or comprises real-if-‘abstract’ units organised in a real-if-‘abstract’ structure, and as the job of speakers is to produce speech with these properties, so the job of the listener is to recognise or calculate the identity of the units in what they hear and the relations between these units.
But a much more interesting prospect is the type of ‘interactionist’ approach that does not impute such reality to language structure at all. That is the view that the raw data of spoken language must be clearly distinguished from the analysis which an observer (lay or specialist) might undertake of it. In other words, there is no implicit structure lurking there in speech, whether phonological or syntactic: structures are inferred by analysts and act as handy descriptive/analytical tools, but they’re not really there. It is a serious criticism of some schools of thought that they treat the analysts’ analysis as being in fact what language is composed of – as though analytical constructs such as noun, verb, IP, DP, etc, actually are somehow or somewhere embodied in utterances. It’s one thing to say that when linguists want to get a handle on what people produce/hear they need to identify units and categorise things – these units and categories are convenient as technical descriptions in order that specialists can spot patterns and talk to each other about them. It’s another thing to say that spoken language consists of these units and categories such that the linguist’s task is to discover them (rather than impose them).*
As Joseph et al (2001: 60) put it, “whereas for the psychologistic structuralist speech comes about through implementation of the speaker’s knowledge of a systematic linguistic structure, for Firth the systematic structure is a linguist’s fiction, resulting from the attempt to understand speech.”** Thus (for example) the nativist scours the child’s productions in order to establish which aspects of linguistic structure must have unfolded in their mind by that point – the more interesting varieties of interactionism make use of structure, on paper, in the analysis, only as a tool to understanding what the child understands.
If both sides in the field of language acquisition, the interactionist and the nativist, share the conceptualisation of the linguist’s task as being one of discovering linguistic structure that actually exists out there/in language, then the differences between the two approaches shrink rather dramatically. But when this conceptualisation is not shared, it makes the ‘interactionist’ approach much harder to evaluate on ‘nativist’ terms, for one thing, and more importantly it keeps the idea of “language structure” where it belongs, in the realm of open questions needing discussion. Linguistic descriptions are convenient (-to-the-linguist) if not indispensible ways of categorising bits of utterances, but they have no life of their own.
*Some books/articles talk about things like Ross’s “discovery” of his island constraints: it would be better to think of things like this as inventions, not discoveries.
** Note the F-word. Amazing chap, obviously, this Firth. I was mightily relieved and heartened to come across that section of Joseph (2001) shortly after tortuously writing an essay labouring to express this point in an essay many moons ago.