Or, how to criticize a scientific theory
Recently, I discovered a book called The Primacy of Grammar by philosopher Nirmalangshu Mukherji. The book is basically an extended, and in my opinion quite good, apologia for biolinguistics as a science. The book is very readable and covers a decent amount of ground, including an entire chapter discussing the viability of incorporating a faculty of music into biolinguistic theory. I highly recommend it.
At one point, while defending biolinguistics from the charge of incompleteness levied by semanticists and philosophers, Mukherji makes the following point.
[D]uring the development of a science, a point comes when our pretheoretical expectations that led to the science in the first place have changed enough, and have been accommodated enough in the science for the science to define its objects in a theory-internal fashion. At this point, the science—viewed as a body of doctrines—becomes complete in carving out some specific aspect of nature. From that point on, only radical changes in the body of theory itself—not pressures from common sense—force further shifting of domains (Mukherji 2001). In the case of grammatical theory, either that point has not been reached or … the point has been reached but not yet recognized.
Mukherji (2010, 122-3)
There are two interesting claims that Mukherji is making about linguistic theory and scientific theory in general. One is that theoretical objects are solely governed by theory-internal considerations. The other is that the theory itself determines what in the external world it applies to.
The first claim reminded me of a meeting I had with my doctoral supervisor while I was writing my thesis. My theoretical explanation rested on the hypothesis that even the simplest of non-function words, like coffee, were decomposable into root objects (√COFFEE) and categorizing heads (n0). I had a dilemma though. It was crucial to my argument that, while categorizing heads had discrete features, roots were treated as featureless blobs by the grammar, but I couldn’t figure out how to justify such a claim. When I expressed my concern to my supervisor, she immediately put my worries to rest. I didn’t need to justify that claim, she pointed out, because roots by their definition have no features.
I had fallen into a very common trap in syntax—I had treated a theory-internal object as an empirical object. Empirical objects can be observed and sensibly argued about. Take, for instance, English specificational clauses (e.g. The winner is Mary). Linguists can and do argue about the nature of these—i.e. whether or they are truly the inverse of predicational clauses (e.g., Mary is the winner)— and cite facts the do so. This is because empirical objects and phenomena are out there in the real world, regardless of whether we study them. Theory-internal objects, on the other hand are not subject to fact-based argument, because, unless the Platonists are right, they have no objective reality. As long as my theory is internally consistent, I can define its objects however I damn please. The true test of any theory is how well it can be mapped onto some aspect of reality.
This brings me to Mukherji’s second assertion, that the empirical domain to a theory is determined by the theory itself. In the context of his book, this assertion is about linguistic meaning. The pretheoretic notion of meaning is what he calls a “thick” notion—a multifaceted concept that is very difficult to pin down. The development of a biolinguistic theory of grammar, though, has led to a thinner notion of meaning, namely, the LF of a given expression. Now obviously, this notion of meaning doesn’t include notions of reference, truth, or felicity, but why should we expect it to? Yes, those notions belong to our common-sense ideas of meaning, but surely at this stage of human history, we should expect that scientific inquiry will reveal our common-sense notions to be flawed.
As an analogy, Aristotle and his contemporaries didn’t distinguish between physics, biology, chemistry, geology, an so on—they were all part of physics. One of the innovations of the scientific revolutions, then, was to narrow the scope of investigation—to develop theories of a sliver of nature. If Aristotle saw our modern physics departments, he might look past all of their fantastic theoretical advances and wonder instead why no one in the department was studying plants and animals. Most critiques of internalist/biolinguistic notions of semantics by modern philosophers and formal semanticists echo this hypothetical time-travelling Aristotle—they brush off any advances and wonder where the theory of truth is.
Taken together, these assertions imply a general principle: Scientific theories should be assessed on their own terms. Criticizing grammatical theory for its lack of a theory of reference makes as much sense as criticizing Special Relativity for its lack of a theory of genetic inheritance. While this may seem to render any theory beyond criticism, the history of science demonstrates that this isn’t the case. Consider, for instance, quantum mechanics, which has been subject to a number of criticisms in its own terms—see: Einstein’s criticisms of QM, Schrödinger’s cat, and the measurement problem. In some cases these criticisms are insurmountable, but in others addressing them head-on and modifying or clarifying the theory is what leads to advances in the theory. Chomsky’s Label Theory, I think, is one of the latter sorts of cases—a theory-internal problem was identified and addressed and as a result two unexplained phenomena (the EPP and the ECP) were given a theoretical explanation. We can debate how well that explanation generalizes and whether it leans too heavily on some auxiliary hypotheses, but what’s important is that a theory-internal addressing of a theory-internal problem opened up the possibility of such an explanation. This may seem wildly counter-intuitive, but as I argued in a previous post, this is the only practical way to do science.
The principle that a theory should be criticized in its own terms is, I think, what irks the majority of linguists about biolinguistic grammatical theory the most. It bothers them because it means that very few of their objections to the theory ever really stick. Ergativity, for instance, is often touted as a serious problem for Abstract Case Theory, but since grammatical theory has nothing to say about particular case alignments, theorists can just say “Yeah, that’s interesting” and move on. Or to take a more extreme case, recent years have seen all out assaults on grammatical theory from people who bizarrely call themselves “cognitive linguists”, people like Vyvyan Evans and Daniel Everett, they claim to have evidence that roundly refutes the very notion of a language faculty. The response of biolinguists to this assault: mostly a resounding shrug as we turn back to our work.
So, critics of biolinguistic grammatical theory dismiss it in a number of way. They say it’s too vague or slippery to be any good as a theory, which usually means they refuse to seriously engage with it, they complain that the theory keeps changing—a peculiar complaint to lodge against a scientific theory, or they accuse theorists of arrogance—a charge that, despite being occasionally true, is not a criticism of the theory. This kind of hostility can be bewildering, especially because a corollary of the idea that a theory defines its own domain is that everything outside that domain is a free-for-all. It’s hard to imagine a geneticist being upset that their data is irrelevant to Special Relativity. I have some ideas about where the hostility comes from but they’ll take me pretty far afield, so I’ll save them for a later post and leave it here.