I grew up in a philosophy department and so I always feel a
warm glow of nostalgia when a book by an eminent practitioner of this dark art turns
his/her attention to my tiny areas of interest. Recently, Jesse Prinz,
Distinguished Professor in Philosophy at CUNY, has directed his attention to
the shortcomings of rationalist efforts in the mental sciences in an effort to
resuscitate empiricist conceptions of mind. The book, Beyond Human Nature, is very much worth looking at (but for god’s
sake don’t buy it!) for it is a good primer on just how little empiricist
conceptions, despite the efforts of its mightiest minds, have to offer those
seriously interested in cognition. I’m not talking modest contributions, I’m
talking NADA! Before proceeding, some
warnings. I am a severe thaasophobe, with an attention span that requires quick
capture. Banalities and weasel wording
can induce immediate narcoleptic seizure. Prinz held me to the end of chapter 6
before Morpheus bared further progress. I never fight with gods. Consequently,
remarks here are limited to the first six chapters and of these they
concentrate mainly on 6, this being dedicated to what I know best, the Chomsky
program in generative grammar. With this caveat, let’s push forward, though caveat lector, this post is way too long.
My main objection with the book is that it refuses to play
by the rules of the game. I have discussed this before (here), but it is worth
reviewing what is required to be taken seriously. Here are the ground rules.
First, we have made many empirical discoveries over the
years and the aim must be to explain these facts. In linguistics these include Island effects,
fixed subject effects, binding theory effects etc. I know I have repeated
myself endlessly about this, but it seems that no matter how often we emphasize
this, critics refuse to address these matters. Prinz is no exception, as we
shall see.
Second, if one is interested in not merely debunking
generative grammar but the whole rationalist enterprise in cognition then
attention must be paid to the results there, and there have been many. We have
reviewed some by Gleitman and Spelke (here, here) but there are many more (e.g.
by Baillargeon on causality and Wynn on numbers a.o.). Prinz touches on these but
is coy about offering counter analyses.
Rather he is satisfied with methodological reflections on the
difficulties this kind of work must deal with and dismisses 40 years of
research and literally hundreds of detailed proposals by pointing out the
obvious, viz. that experiments must be done carefully and that this is hard.
Not exactly big news.
Third, though acknowledging these data points is a necessary
first step, more is required. In addition one must propose alternative mechanisms
that derive the relevant facts. It is
not enough to express hopes, desires, expectations, wishes etc. We need
concrete proposals that aim to explain the phenomena. Absent this, one has contributed nothing to
the discussion and has no right to be taken seriously.
That’s it. These are the rules of the game. All are welcome
to play. So what does Prinz do. He adopts a simple argumentative form, which
can be summarized as follows.
1.
He accepts that there are biological bases for
cognition but that they vastly underdetermine human mental capacities. He dubs his
position “nurturism” (just what we need another neologism) and he contrasts
with “naturism.”[1]
2.
His main claim is that cognition has a heavy
cultural/environmental component and that rationalism assumes that “all brains
function in the same way…” and “our behavior is mostly driven by biology”
(102).
3.
He reviews some of the empirical arguments for
rationalism and concludes that they are not apodictic, i.e. it is logically
possible that they are inconclusive.
4.
He buttresses point 3 by citing work purporting
to show methodological problems with rationalist proposals. Together 3 and 4
allow Prinz to conclude that matters are unsettled, i.e. to declare a draw.
5.
Given the draw, the prize goes to the “simpler”
theory. Prinz declares that less
nativism is always methodologically preferable to more and so given the
empirical standoff, the laurel goes to the empiricists.
That’s the argument. Note what’s missing: no counter
proposals about relevant mechanisms. In short, Prinz is violating the rules of
the game, a no-no. Nonetheless, let’s
look a bit more into his argument.
First, Prinz allows that there is some innate structure to
minds (e.g. see around 152).[2]
The question is not whether there is native structure, but how much and what
kind. For Prinz, associationist
machinery (i.e. anything coming in through the senses with any kind of
statistical massaging) is permissible. Domain specific modular knowledge with
no simple perceptual correlates is not (c.f. 171).
This is standard associationsim at its grubbiest. So despite his insistence about how the truth
must lie at some point between the naturist and nurturist extremes, Prinz
erects his standard on pretty conventional empiricist ground. No modularity for
him. It’s general learning procedures or nothing.
Why does Prinz insist on this rather naïve version of
empiricism? He wants to allow for cultural factors to affect human mental life.
For some reason. he seems to think that this is inconsistent with rationalist
conceptions of the mind. Why is beyond
me. Even if the overall structure of
minds/brains is the same across species, this does not prevent modulation by
all sorts of environmental and cultural factors. After all, humans have four
chamber hearts as a matter of biology but how good an individual heart is for
marathons is surely heavily affected by cultural/environmental factors (e.g.
training regimens, diet, altitude, blood doping etc.).
So too with cognition.
Indeed, within linguistics, this has been recognized as a boundary
condition on reasonable theorizing since the earliest days of generative
grammar. The standard view is that UG provides design specifications for particular
Gs, and particular Gs can be very different from one another. In a standard
P&P theories the differences are related to varying kinds of parameter
settings, but even non-parameter theories recognize the fact of variation and
aim to explain how distinct Gs can be acquired on the basis of PLD.
Indeed, one of the standard arguments for some cognitive
invariance (i.e. UG) arises from the fact that despite all the attested variation
among particular Gs, they have many properties in common. Comparative syntax
and the study of variation has been the source of some of the strongest
arguments in favor of postulating a rich domain specific UG. In short, the
problem from the outset has been to explain both
the invariance and the variation. Given all of this, Prinz’s suggestions that
rationalists ignore variation is simply mystifying.[3]
Moreover, he seems ignorant of the fact that to date this is
really the only game in town. Prinz is
staking a lot on the new statistical learning techniques to supply the
requisite mechanisms for his empiricism. However, to date, purely statistical
approaches have had rather modest success. This is not to say that stats are
useless. They are not. But they are not the miracle drug that Prinz seems to
assume they are.
This emerges rather clearly in his discussion of that old
chestnut, the poverty of the stimulus argument (POS) using the only example
that non-linguists seem to understand, polar questions. Sadly, Prinz’s presentation of the POS
demonstrates once again how subtle the argument must be for he clearly does not
get it. The problem (as Paul Pietroski went over in detail here and that I
reviewed again here) is to explain constrained homophony (i.e. the existence of
systematic gaps in sound-meaning pairings).
It is not to explain how to affix
stars, question marks and other diacritics to sentences (i.e. not how to rank linguistic
items along an acceptability hierarchy). There has been a lot of confusion on
this point and it has vitiated much of the criticism of Chomsky’s original
argument. The confusion likely stems
from the fact that whereas an acceptability hierarchy is a standard byproduct
of a theory of constrained homophony, the converse is not true, i.e. a theory
of acceptability need not say much about the origins of constrained
homophony. But as the question of
interest is how to relate sound and meaning (viz. the generative procedures
relating them), simply aiming to distinguish acceptable from unacceptable
sentences is to aim in the wrong direction.
Why is this important? Because of the myriad dumb critiques
of Chomsky’s original POS argument that fail precisely because they misconstrue
the explanadum. The poster child of this
kind of misunderstanding is Reali and Christiansen (R&C), which, of course,
Prinz points to as providing a plausible statistical model for language
acquisition. As Prinz notes (2513),
P&C’s analysis counts bigram and trigram word frequencies and from just so
counting, is able to discriminate (1) from (2).
(1) Is
the puppy that is barking angry?
(2) Is
the puppy barking is angry?
Prinz is delighted with this discovery. As he says:
This is an extremely important
finding. By their second birthday, children have heard enough sentences to
select between grammatical and ungrammatical questions even when they are more
complex than the questions they have heard (loc 2513).
The problem however is that even if this is correct, the
R&C proposal answers the wrong question. The question is why can’t kids
form sentences like (2) with the meaning “is it the case that the angry puppy
is barking” on analogy with (1)’s meaning “is it the case that the barking
puppy is angry”? This is the big fact. And it exists quite independently of the
overall acceptability of the relevant examples. Thus (3) carries only the
meaning we find in (1), not (2) (i.e. (3) cannot mean “is it the case that the
puppy that barked was the one that Bill kissed.”).
(3) Did
the puppy Bill kissed bark
This is the same fact that (1) and (2) discuss but with no
unacceptable string to account for, i.e. no analogue of (2). Bigrams and trigrams are of no use here. What
we need is a rule relating form to meaning and an explanation of why some
conceivable rules are absent resulting in the inexpressibility of some meanings
by some sentences. Unfortunately for
Prinz, R&C’s proposals don’t even address this question let alone provide a
plausible answer.
Why do Prinz and R&C so completely misunderstand what
needs explaining. I cannot be sure, but here is a conjecture. They confuse data
coverage with using data to probe structure.
For Chomsky, the contrast between (1) and (2) results from the fact that
(1) can be generated by a structure dependent grammar while (2) cannot be. In
other words, these differences in acceptability reflect differences in possible
generative procedures. It is generative
procedures that are the objects of investigation not the acceptability data. As Cartwright argued (see here), empiricists
are uncomfortable with the study of underlying powers/structures, viz. here the
idea that there are mental powers with their own structural requirements. Empiricists
confuse what something does with what it is.
This confusion is clearly at play here with the same baleful effects
that Cartwright noted are endemic to empiricist conceptions of scientific
explanation.
I could go on sniping at Prinz’s misunderstandings and poor
argumentation. And I think I will do so to make two more points.
First, Prinz really seems to have no idea how poor standard
empiricist accounts have been. Classical
associationist theories have been deeply unsuccessful. I want to emphasize this for Prinz sometimes
leaves the impression that things are not nearly so hopeless. They are. And not only in the study of humans, but in
mammal cognition quite generally.
Gallistel is the go-to guy on these issues (someone that I
am sure that Prinz has heard of after all he just teaches across the bridge at
Rutgers). He and King review some of the
shortcomings in Memory and the
Computational Brain, but there is a more succinct recapitulations of the
conceptual trials and empirical tribulations of the standard empiricist learning
mechanisms in a recent paper
(here). It’s not pretty. Not only are there a slew of conceptual
problems (e.g. how to deal with the effects of non-reinforcement (69)), but the
classical theories fail to explain much at all. Here’s Gallistel’s conclusion
(79):
Associationist theories have not
explained either the lack of effect of partial reinforcement on reinforcements
to acquisition or the extinction-prolonging effect of partial reinforcement.
Nor have they explained spontaneous recovery, reinstatement, renewal and
resurgence except by ad hoc parametric assumptions…I believe these failures
derive from the failure to begin with a characterization of the problem that
specific learning mechanisms and behavioral systems are designed to solve. When
one takes an analysis of the problems as one’s point of departure…insights
follow and paradoxes dissolve. This perspective tends, however, to lead the
theorist to some version of rationalism, because the optimal computation will
reflect the structure of the problem, just as the structure of the eye and the
ear reflect the principles of optics and acoustics.
Gallistel’s arguments hinge on trying to understand the
detailed mechanisms underlying specific capacities. It’s when the rubber hits
the road that the windy generalities of empiricism start looking less than
helpful. Sadly, Prinz never really gets
down to discussions of mechanisms, i.e. he refuses to play by the rules. Maybe it’s the philosopher in him.
So what does Prinz do instead? He spends a lot of time discussing
methodological issues that he hopes will topple the main results. For example,
he discusses how difficult it can be to interpret eye gaze, the standard
measure used in infant and toddler studies (1547). Eye gaze can be hard to interpret. What
change it is indexing can be unclear. Sometimes it indexes stimulus similarity
other times novelty. Sometimes it is hard to tell if it’s tracking a surface
change in stimulus or something deeper. And that’s why people who use eye gaze
measures try to determine what eye gaze duration is actually indexing in the
particular context in which it’s being used.
That’s part of good experimental design in these areas. I know this
because this is extensively discussed in the lab meetings I sit in on (thanks Jeff)
whenever eye gaze duration is used to measure knowledge in the as yet
inarticulate. The technique has been
used for a long long time. Hence its potential pitfalls are well known and for
precisely this reason it is very unlikely that all the work that uses it will go down the intellectual drain for
the trivial methodological reasons that Prinz cites. To put it bluntly,
Baillargeon, Carey, Spelke, Wynn etc. are not experimentally inept. As Prinz notes, there are hundreds
(thousands?) of studies using this technique that all point in the same
rationalist direction. However blunt a
measure eye-gaze is, the number of different kinds of experiments all pointing
to the same conclusion is more than a little suggestive. If Prinz wants to bring this impressive
edifice crashing down, he needs to do a lot more than note what is common
knowledge, viz. that eye gaze needs contextual interpretation.
And of course, Prinz knows this. He is not aiming for victory. He is shooting
for a tie (c.f. 1512). He doesn’t want to show that rationalists wrong
(just that “they don’t make their case”) and empiricists right (ok, he does want this but clearly believes this
goal is out of reasonable reach), rather he wants to muddy the waters, to
insinuate that there is less to the myriad rationalist conclusions than meets
the eye (and there is a lot here to meet an unbiased eye), and consequently
(though this does not follow as he no doubt knows) that there is more to
empiricist conceptions than there appears to be. Why? Because he believes that
“empiricism is the more economical theory” (1512) and should be considered
superior until rationalist prove they are right.
This strategy, aside from setting a very low bar for
empiricist success, conveniently removes the necessity of presenting
alternative accounts or mechanisms for any phenomena of interest. Thus, whereas
rationalists try to describe human cognitive capacities and explain how they
might actually arise, Prinz is satisfied with empiricist accounts that just
point out that there is a lot of variation in behavior and gesture towards
possible socio-environmental correlates. How this all translates into what
people know or they do what they do is not something Prinz demands of
empiricist alternatives. [4]
He is playing for a tie, assured in the belief that this is all he needs. Why
does he believe this? Because he believes that Empiricism is “a more economical
theory.”
Why assume this? Why think that empiricist theories are
“simpler”? Prinz doesn’t say, but here is one possible reason: domain
specificity in cognition requires an account of its etiology. In other words,
how did the innate structure get there (think Minimalism)? But, if this is the reason then it is not
domain specificity that is problematic, but any difference in cognitive power
between descendant and ancestor. Here’s what I mean.
Say that humans speak language but other animals don’t. Why?
Here’s one explanation: we have domain specific structure they don’t. Here’s another, we have
computational/statistical capacities they don’t. Why is the second account
inherently methodologically superior to the first? The only reason I can think
of is that enhanced computational/statistical capacities are understood as
differences in degree (e.g. a little more memory) while domain specific
structures are understood as differences in kind. The former are taken to be easy to explain,
the latter problematic. But is this true?
There are two reasons to think not. Consider the language
case. Here’s the big fact: there’s nothing remotely analogous to our linguistic
capacities in any other animal. If this is due to just a slight difference in
computing capacity (e.g. some fancier stats package, a little more memory) then
we need a pretty detailed story demonstrating this. Why? Because it is just as
plausible that a little less computing capacity should not result in this
apparently qualitative difference in linguistic capacity (indeed, this was the
motivation behind the earlier teach-the-chimps/gorillas-to-talk efforts). What
we might expect is more along the following lines: slower talk, shorter
sentences, fewer ‘you know’s interspersed in speech. But a complete lack of
linguistic competence, why expect this? Maybe the difference really is just a
little more of what was there before, but, as I said, we need a very good story
to accept this. Need I say that none has been provided?
Second, there are many different ways to adding to
computational/statistical power. For example, some ways of statistically
massaging data are computationally far more demanding than others (e.g. it is
no secret that Bayesianism if interpreted as requiring updating of all relevant
alternatives is too computationally extensive to be credible and that’s why
many Bayesians claim not to believe that this is possible).[5]
If the alternative to domain specific structure is novel (and special) counting
methods then what justifies the view that the emergence of the latter is easier
to explain than the former?
Prinz’s methodological assumption here is not original. Empiricists often assume that rationalism is
the more complex hypothesis. But this really depends on the details and no
general methodological conclusions are warranted. Sometimes domain specific structures allow
for economizing on computational resources.[6]
At any rate, none of this can be adjudicated a priori. Specific proposals need to be proposed and examined. This is how the game is played. There are no
methodological shortcuts to the argumentative high ground.
This post has gone on far too long. To wrap up then: there is a rising tendency
to think well again of ideas that have been deservedly buried. Prinz is the latest herald of the
resurrection. However, empiricist conceptions of the mind should be left to
mold peacefully with other discredited ideas: flat earth, epicycles, and
phlogiston. Whatever the merits of these
ideas may once have been (these least three, did have some once) they are no
longer worth taking seriously. So too with classical empiricism, as Prinz’s
book ably demonstrates.
[1]
I’m going to drop the naturism/nurturism lingo and just return to the
conventional empiricism/rationalism labels.
[2]
All references are to the Kindle version.
[3]
I’m no expert in these areas but it seems obvious to me that the same can be
said about most work in cognitive psychology. Actually, here, if anything, the
obsession with dealing with individual differences (aka cognitive variation)
has retarded the search for invariances.
In the last decades this has been partly assuaged. Baillargeon, Spelke,
Carey, Gleitman a.o. have pursued research strategies logically analogous to
the one described above in generative grammar.
[4]
I should be careful here. I am discussing capacities, but Prinz mainly trucks
in behavior loc 112-132). Most rationalists aim to understand the structure of
mental capacities, not behavior. What someone does is only partially determined
by his/her mental capacities. Behavior,
at least for linguists of the generative variety, is not an object of study, at
least at present (and in my own view, never).
I am going to assume that Prinz is also interested in capacities, though
if he is not then his discussion is irrelevant to most of what rationalists are
aiming to understand.
[6]
Berwick had an excellent presentation to this effect at the recent LSA meeting
in Boston. I’ll see if I can get the slides and post them.
