REVISED July 15/2013
First off, thanks to Ben, David and Andrew for correcting me. The discussion is not in Aspects as stated below (or at least in the way I recalled: but see chapter 4 for some discussion), but in Current Issues in Linguistic Theory. So don't fret if in your (re)reading of Aspects chapter 1 you miss it. Ben also asked that I expand the discussion a bit of the relation between observational and descriptive adequacy. I have added something at the end to expatiate a bit on the distinction. Thanks to Avery for adding to this. I encourage people to look at the comment section for further enlightenment.
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In the last several posts I have defended the position that one of the benchmarks for theory evaluation ought to be how well a given proposal helps answer a central why question. Plato’s Problem lays out the central puzzle in GB, and it is worth reviewing how Generative Grammar (GG) incorporated concern for both low-level observational details and higher level problems in evaluating ongoing proposals. The locus classicus is, of course, in Aspects chapter 1.
First off, thanks to Ben, David and Andrew for correcting me. The discussion is not in Aspects as stated below (or at least in the way I recalled: but see chapter 4 for some discussion), but in Current Issues in Linguistic Theory. So don't fret if in your (re)reading of Aspects chapter 1 you miss it. Ben also asked that I expand the discussion a bit of the relation between observational and descriptive adequacy. I have added something at the end to expatiate a bit on the distinction. Thanks to Avery for adding to this. I encourage people to look at the comment section for further enlightenment.
****
In the last several posts I have defended the position that one of the benchmarks for theory evaluation ought to be how well a given proposal helps answer a central why question. Plato’s Problem lays out the central puzzle in GB, and it is worth reviewing how Generative Grammar (GG) incorporated concern for both low-level observational details and higher level problems in evaluating ongoing proposals. The locus classicus is, of course, in Aspects chapter 1.
BTW, before going on, I found to my dismay that students no
longer read Chapter 1 as a matter of course. In teaching intro to Minimalism
here at the LSA summer institute, I ran a random poll of the class and
discovered that much less than a third had ever read it. Given that this is one of the seminal
documents in GG and lays out many of the basic foundational premises as clearly
as has ever been done, this is just nuts. So, if you dear reader have never
read it (in fact multiple times (aim for about 50)), then stop reading this
silly blog now and go and read it!!
Ok, to resume: In Aspects
Chomsky distinguished three levels of empirical adequacy:
(i)
Observational Adequacy
(ii)
Descriptive Adequacy
(iii)
Explanatory Adequacy
In the context of Plato’s Problem (PP) they were interpreted
as follows: a proposed grammar G of a language L (i.e. GL) is observationally
adequate if it covers the relevant data points (generally consisting of
acceptability(-under-an-interpretation) judgments). A GL is
descriptively adequate if it accurately describes the internal (steady) state
of a native speaker of L. Last, a theory of UG is explanatorily adequate when
it, in combination with the PLDL (the primary linguistic data of L
that the child uses to attain GL)
can derive the descriptively adequate GL. We can then extend the
notion of explanatory adequacy to GL as well: the proposal is explanatory
just in case it covers the relevant observational data and is derivable from UG
given PLDL.
Note the important distinction between observational and
descriptive adequacy. The evaluation of GLs faces in two directions:
towards the sentential observations/judgments that derive from descriptively
adequate Gs and towards FL from which these Gs descend. Thus, descriptive adequacy commits hostages
to the structure of FL for a proposal fails to be such if it fails to grow out
of FL when appropriately watered with PLDL. In other words, covering
the sample data was never considered
in itself sufficient for attaining descriptive
adequacy. This required attention to all three levels, i.e. to cover the
data with the “correct” grammar derived from an adequate UG.
I always thought that one could add a forth level to this,
doing for UG what (ii) does for particular Gs:
(iv)
Explanatory Descriptive Adequacy
This last would select out the actual UG we have, not merely one capable of deriving GL
from PLDL + some UG. However, given how hard the problem of
finding any explanatorily adequate UG, it makes sense to be satisfied with
theories of UG that can manage (iii) (to my knowledge, none has yet been produced,
though there are sketches). I return to (iv) below.
Not surprisingly, within the context of PP all three levels
play an important justificatory role for particular analyses. Thus, an account
that fails to “cover” the relevant judgment data, is less well regarded than
one that does. So too, if a particular story covers these data but does not
describe our actual G, is justly discarded.
One relevant question is how one might know that an account that is
observationally adequate is nonetheless possibly false. One way is that it fails to comport with what
we take to be features of UG (others include being “too complex and inelegant,”
“missing a generalization,” etc.[1]). So, for example, we might find a theory that
covers the relevant language particular data but invokes operations that are UG
inconsistent, something we discerned in studying the Gs of other Ls. As we assume that any given Gs must be
structurally consistent with other Gs (e.g. the G of English can constrain what
we take to be a possible rule in the G of Japanese), we can argue that Gs that
are observationally adequate (i.e. cover the relevant facts within any given L)
are nonetheless inadequate as they invoke operations or principles inconsistent
with what we find in other Gs. As any
child, we assume, can learn any language, the G that it actually (accidentally)
acquires should look similar to the other Gs that it could have acquired. In this way, the larger explanatory goal,
discovering the structure of FL/UG, impacts our evaluation of candidate
proposals.
A similar three level scheme with a regulative role for
Darwin’s Problem can be developed for the Minimalist Program (MP). Recall that
the aim is to understand why we have the FL/UG we have and not some other. So a
MP proposal will be observationally adequate if it replicates the right “laws
of grammar.” (e.g. the principles within GB are “roughly” observationally
adequate). An MP proposal will be descriptively adequate if they describe the
actual FL/UG that is our biological endowment and a theory will be
explanatorily adequate if combined with a plausible evolutionary scenario it
can account for how the descriptively adequate FL/UG arose in the species. I
have elsewhere discussed various intermediate projects that could push this
explanatory project forward. Here I just want to note that as in the discussion
above, it is useful to have the higher- level explanatory goal regulate the
evaluation of specific proposals.
I hope it goes without saying that Plato’s and Darwin’s
Problems are pursued in tandem and not seriatim. Both are looking for the
correct FL/UG. It’s a factor in evaluating descriptive adequacy in the context
of Plato’s Problem and it is the object of inquiry in pursuing Darwin’s. Observational concerns affect explanatory
ambitions and, hopefully, the reverse is true as well. Thus, the projects are not separate, but go
hand in hand. Nonetheless, it is
interesting to note that as Chomsky likes to say “from the earliest days of
Generative Grammar” between observational work and higher level questions that
this work was in the service of pursuing. Thus, the minimalist emphasis on
explanation and the insistence that it play a central role in theory evaluation
is hardly a GG novelty. It was always such, and now it is such in spades.
Addendum:
Here's how I have understand the distinction between observational and descriptive adequacy. Chomsky draws an implicit distinction between grammars that cover the relevant data of interest and grammars that accurately describe a speaker's mental grammatical state. The former grammars are observationally adequate, the latter descriptively adequate. Now, as Avery nicely observes, there are even levels of observational adequacy: does it cover the right range of acceptability judgments, get the right interpretations (theta roles, scope, binding), does it "capture" the apparent generalizations. Grammars that do so are observationally adequate. Note, this is not a trivial hurdle. A good observationally adequate grammar is nothing to sneeze at. Even more so, when as I suggested, that we extend the same courtesy to UGs in the context of MP. However, being observationally adequate is one virtue, being descriptively adequate another. A Grammar of L attains descriptive adequacy if it correctly describes the mental state achieved by a competent speaker of L (actually an ideal speaker-hearer, but let's put that aside). What makes for the gap between observational and descriptive adequacy? Well, being acquirable as a product of FL. Descriptively adequate grammars are those that FL/UG generate on the basis of PLD of L. So, among the possible observationally adequate grammars, the descriptively adequate ones are those that are products of FL. Thus descriptive adequacy adverts to the concerns of Plato's Problem, a sketch of the latter bearing (at least implicitly) on the step from observational to descriptive adequacy.
If this is correct, then from the earliest days of GG, Chomsky has insisted placing the evaluation of grammatical proposals in the widest possible context, with Plato's Problem (a later dubbing) playing a central role. This role became more prominent, in my view, as we made more progress. However, it was there from the start. Minimalism has enriched this evaluative measure yet again by highlighting various other factors (e.g. Ockham, Darwin's Problem, etc.) and including them as relevant measures of theory evaluation. Of course, there is no algorithm for weighing these factors and trading them off against one another when they conflict. But that's par for the course. That's a domain for scientific judgment, not mindless rules of method. However, it is easy to ignore the more abstract concerns on favor of covering he more easily available data points. The discussion of levels of adequacy is a useful conceptual reminder that the fish we are trying to fry is a very big one and that there are many things that go into frying it.
Addendum:
Here's how I have understand the distinction between observational and descriptive adequacy. Chomsky draws an implicit distinction between grammars that cover the relevant data of interest and grammars that accurately describe a speaker's mental grammatical state. The former grammars are observationally adequate, the latter descriptively adequate. Now, as Avery nicely observes, there are even levels of observational adequacy: does it cover the right range of acceptability judgments, get the right interpretations (theta roles, scope, binding), does it "capture" the apparent generalizations. Grammars that do so are observationally adequate. Note, this is not a trivial hurdle. A good observationally adequate grammar is nothing to sneeze at. Even more so, when as I suggested, that we extend the same courtesy to UGs in the context of MP. However, being observationally adequate is one virtue, being descriptively adequate another. A Grammar of L attains descriptive adequacy if it correctly describes the mental state achieved by a competent speaker of L (actually an ideal speaker-hearer, but let's put that aside). What makes for the gap between observational and descriptive adequacy? Well, being acquirable as a product of FL. Descriptively adequate grammars are those that FL/UG generate on the basis of PLD of L. So, among the possible observationally adequate grammars, the descriptively adequate ones are those that are products of FL. Thus descriptive adequacy adverts to the concerns of Plato's Problem, a sketch of the latter bearing (at least implicitly) on the step from observational to descriptive adequacy.
If this is correct, then from the earliest days of GG, Chomsky has insisted placing the evaluation of grammatical proposals in the widest possible context, with Plato's Problem (a later dubbing) playing a central role. This role became more prominent, in my view, as we made more progress. However, it was there from the start. Minimalism has enriched this evaluative measure yet again by highlighting various other factors (e.g. Ockham, Darwin's Problem, etc.) and including them as relevant measures of theory evaluation. Of course, there is no algorithm for weighing these factors and trading them off against one another when they conflict. But that's par for the course. That's a domain for scientific judgment, not mindless rules of method. However, it is easy to ignore the more abstract concerns on favor of covering he more easily available data points. The discussion of levels of adequacy is a useful conceptual reminder that the fish we are trying to fry is a very big one and that there are many things that go into frying it.
[1]
For a classic argument like this see Chomsky’s discussion of the inadequacy of
Phrase Structure Grammars as one’s that clearly are too cumbersome, redundant
and miss obvious generalizations. In effect, they fail to be compact enough.
