Randomized controlled trials

The gold standard in data gathering is the standardized controlled trial. One of its principle charms, apparently, is the idea that if done right it frees one from the onerous demands of theory. If done well, just on its own, it establishes solid facts all the while freeing 

" empirical investigation from implausible and arbitrary theoretical and statistical assumptions"

This, it turns out, is wrong. Cartwright and Deaton (here) argue that there is no way to bootstrap data without quite a bit of theory. The setting of the discussion is Economics and policy. But the moral applies quite generally. The idea that experiments if done carefully speak for themselves and give us insight is currently fashionable. The idea that theory is dispensable and often "arbitrary" and misleading is rife even in linguistics. If Cartwright and Deaton are right this is just palin wrong. There is no magic bullet. 

The Rationalism of Generative Grammar

 The theory of mind that Generative Grammar endorses is evidently rationalist. An earlier post gestured (don’t you love that word!) to these philosophical roots. Interestingly (though not surprisingly), the scientific metaphysics is as well. Here’s what I mean.

I was recently reading a fascinating book by Nancy Cartwright -The Dappled World- (highly recommended for philo of science aficionados) in which she contrasts the role of powers/natures/capacities versus regularities in scientific theory.  The classical empiricist/Humean tradition rejected the former as occult residues of an earlier search for Aristotelian essences and insisted on founding all scientific knowledge on “the kinds of qualities that appear to us in experience (79)” (recall the dictum: nothing in the intellect that is not first in the senses!). Modern empiricists/Humeans endorse this antipathy to “powers” by treating the laws of nature as summaries of “what things do (82).” Cartwright contrasts this with the view that laws are about powers/natures/capacities, which is not about what things do but “what it is in their nature to do (82).” Here’s a quote that provides a good feel for what she has in mind:

What we have done in modern science, as I see it, is to break the connection between what the explanatory nature is- what it is in and of itself- and what it does. An atom in an excited state, when agitated, emits photons and produces light. It is, I say, in the nature of an excited atom to produce light. Here the explanatory feature –an atom’s being in an excited state- is a structural feature of the atom…For modern science what something really is -how it is defined and identified- and what it is in its nature to do are separate things.

In short, there is an important metaphysical distinction that divides Empiricists and Rationalists. For the former the laws of nature are in effect summaries (perhaps statistical) of “actually exhibited behaviors”, for the latter they describe abstract “configurations of properties” or “structures.” These latter underlie, but are distinct from, behavior (“what appears on the surface”), these being “the result of the complex interaction of natures (81).”

Cartwright notes the close connection between the Rationalist conception of powers/natures/capacities and the analytic method of inquiry characteristic of the physical sciences, often called “Galilean idealization.” She also provides several interesting reasons for insisting on the distinction between what something is versus what it does. Here are two.

First, given that visible behavior is an interaction effect of complex natures it is often impossible to actually see the contribution of the power one is interested in, even in the very contrived circumstances of controlled experiments. She illustrates this using Coulomb’s law and the interfering effects of gravity. As she points out:

Coulomb’s law tells not what force charged particles experience but rather what it is in their nature, qua charged, to experience…What particles that are both massive and charged actually experience will depend on what tendency they have qua charged and what qua massive (82).

Thus, actual measurable forces are the result of the interaction of several powers and it takes great deal of idealization, experimentation, calculation and inference to (a) simply isolate the effects of just one and segregate it from everything else, viz. to find out how two charged bodies “ ‘would interact if their masses were zero.’ ”[1]  And (b) to use the results from (a) to find out what the actual powers involved are:

The ultimate aim is to find out how the charged bodies interact not when their masses are zero, nor under any other specific set of circumstances, but how they interact qua charged. 

Second, contrary to the accepted wisdom more often than not in the real world the same cause is not followed by the same effect.  In fact, generating stable relations between cause and effect requires very careful contrivance in manufactured artificial experimental settings.  Cartwright refers to these as nomological engines; set-ups that allow for invariant regular connections between what powers/natures/capacities can do and what they actually do. Except in such settings the Humean dictum that effects regularly follow causes is hardly apparent.

Outside the supervision of a laboratory or the closed casement of a factory-made module, what happens in one instance is rarely a guide to what will happen in others.  Situations that lend themselves to generalizations are special…(86).

Now, the punch line: Cartwright’s discussion should sound familiar to generative ears. Chomsky’s important distinction between competence and performance is a rationalist one.  UG is a theory of human linguistic powers/natures/capacities, not a theory of linguistic behavior.  UG is not a summary of behavioral regularities. Indeed, linguistic behavior is a very complex interaction effect with competence being one of many (very poorly understood) factors behind it. The distinction between what a speaker knows (competence) and what a speaker puts this knowledge to use (performance) echoes Cartwright’s rationalist themes. Similarly, the rejection of the idea that linguistic competence is just (a possibly fancy statistical) summary of behavior should be recognized as the linguistic version of the general Rationalist endorsement of the distinction between powers/natures/capacities and their behavioral/phenomenal effects. Lastly, the Rationalist conception buttresses a reasonable skepticism against a currently common (and sadly fashionable) view that language acquisition is largely a statistical exercise where minds track environmental regularities, a view more congenial with the empiricist conception that identifies what something is with what it does. This cannot be true: for there are precious few such regularities in the wild and what there is won't (in fact cannot) alone reveal the powers, capacities and natures of the underlying object of linguistic interest, i.e. the fine structure of UG.

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[1] Cartwright observes that though doing (1) is difficult it is “just a stage; in itself this information is uninteresting.” (83-4), a point not unlike that made in a previous post.