Let’s say we find two languages displaying a common pattern,
or two languages converging towards a common pattern, or even all languages
doing the same. How should we explain this? Stephen Anderson (here,
and discussed by Haspelmath here)
notes that if you are a GGer there are three available options: (i) the nature
of the input, (ii) the learning theory and (iii) the cognitive limits of the
LAD (be they linguistically specific or domain general). Note that (ii) will
include (iii) as a subpart and will have to reflect the properties of (i) but
will also include all sorts other features (cognitive control, structure of memory
and attention, the number of options the LAD considers at one time etc.). These,
as Anderson notes, are the only options available to a GGer for s/he takes G
change to reflect the changing distribution of Gs in the heads of a population
of speakers. Or, to put this more provocatively: languages don't exist apart
from their incarnation in speakers’ minds/brains. And given this, all
diachronic “laws” (laws that explain how languages or Gs change over time) must
reflect the cognitive, linguistic or computational properties of human
minds/brains.
This said, Haspelmath (H) observes (here and here) (correctly in my view) that
GGers have long “preferred purely synchronic ways of explaining typological
distributions,” and by this he means explanations that allude to properties of
the “innate Language Faculty” (see here for
discussion). In other words, GGers like to think that typological differences
reflect intrinsic properties of FL/UG and that studying patterns of variation
will hence shed light on its properties. I have voiced some skepticism
concerning this “hence”
here. In what follows I would like to comment on H’s remarks on a similar
topic. However, before I get into details I should note that we might not be
talking about the same thing. Here’s what I mean.
The way I understand it, FL/UG bears on properties of Gs not
on properties of their outputs. Hence, when I look at typology I am asking how
variation in typologies and historical change might explain changes in Gs. Of
course, I use outputs of these Gs to try to discern the properties of the
underlying Gs, but what I am interested in is G variation not output variation. This concedes that one might achieve similar
(identical?) outputs from different congeries of G rules, operations and filters.
In effect, whereas changing surface patterns do signal some change in the
underlying Gs, similarity of surface patterns need not. Moreover, given our
current accounts there is (sadly) too many roads to Rome, thus the fact that
two Gs generate similar outputs (or have moved towards similar outputs from
different Gish starting points) does not imply that they must be doing so in
the same way. Maybe they are and maybe not. It really all depends.
Ok back to H. He is largely interested in the (apparent) fact (and let’s stipulate that H is correct) that there exist “recurrent paths of changes,” “near universal tendencies” (NUT) that apply in “all or a great majority of languages.”[1] He is somewhat skeptical that we have currently identified diachronic mechanisms to explain such changes and that those on the market do not deliver: “It seems clear to me that in order to explain universal tendencies one needs to appeal to something stronger than “common paths of change,” namely change constraints, or, mutational constraints…” I could not agree more. That there exist recurrent paths of change is a datum that we need mechanisms to explain. It is not yet a complete explanation. Huh?
Recall, we need to keep our questions clear. Say that we have
identified an actual NUT (i.e. we have compelling evidence that certain kinds
of G changes are “preferred”). If we have this and we find another G changing
in the same direction then we can attribute this to that same NUT. So we explain the change by so attributing it.
Well, in part: we have identified the kind of thing it is even if we do not yet
know why these types of things exist. An
analogy: I have a pencil in my hand. I open it. The pencil falls. Why?
Gravitational attraction. I then find out that the same thing happens when I
have a pen, an eraser, a piece of chalk (yes, this horse is good and dead!) and
any other school supply at hand. I conclude that these falls are all instances
of the same causal power (i.e.
gravity). Have I explained why when I pick up a thumbtack and let it loose and
it too falls that it falls because of gravity? Well, up to a point. A small
point IMO, but a point nonetheless. Of
course we want to know how Gravity
does this, what exactly it does when it does it and even why it does is the way
that it does, but classifying phenomena into various explanatory pots is often
a vital step in setting up the next step of the investigation (viz. identifying
and explaining the properties of the alleged underlying “force”).
This said, I agree that the explanation is pretty lame if
left like this. Why did X fall when I dropped it? Because everything falls when
you drop it. Satisfied? I hope not.
Sadly, from where I sit, many explanations of typological
difference or diachronic change have this flavor. In GG we often identify a
parameter that has switched value and (more rarely) some PLD that might have
led to the switch. This is devilishly hard to do right and I am not dissing
this kind of work. However, it is often very unsatisfying given how easy it is
to postulate parameters for any observable difference. Moreover, very few
proposals actually do the hard work of sketching the presupposed learning
theory that would drive the change or looking at the distribution of PLD that
the learning theory would evaluate in making the change. To get beyond the weak
explanations noted above, we need more robust accounts of the nature of the
learning mechanisms and the data that was input to it (PLD) that led to the
change.[2]
Absent this, we do have an explanation of a very weak sort.
Would H agree? I think so, but I am not absolutely sure of
this. I think that H runs together things that I would keep separate. For
example: H considers Anderson’s view that many synchronic features of a G are
best seen as remnants of earlier patterns. In other words, what we see in
particular Gs might be reflections of “the shaping effects of history” and “not
because the nature of the Language Faculty requires it” (H quoting Anderson: p.
2). H rejects this for the following reason: he doesn’t see “how the historical
developments can have “shaping effects” if they are “contingent” (p. 2). But
why not? What does the fact that
something is contingent have to do with whether it can be systematically
causal? 1066 and all that was contingent, yet its effects on “English” Gs has
been long lasting. There is no reason to think that contingent events cannot
have long lasting shaping effects.
Nor, so far as I can tell, is there reason to think that
this only holds for G-particular “idiosyncrasies.” There is no reason in principle why historical contingencies
might not explain “universal tendencies.” Here’s what I mean.
Let’s for the sake of argument assume that there are around
50 different parameters (and this number is surely small). This gives a space
of possible Gs (assuming the parameters are independent) of about 1,510,000,000. The current estimate of different
languages out there (and I assume, maybe incorrectly, Gs) is on the order of
7,000, at least that’s the number I hear bandied about among typologists. This
number is miniscule. It covers .0005% of the possible space. It is not
inconceivable that languages in this part of the space have many properties in
common purely because they are all in the same part of the space. These common
properties would be contingent in a UG sense if we assumed that we only
accidentally occupy this part of the space. Or, had we been dropped into another part of the G space we would have developed Gs without these
properties. It is even possible that it is hard to get to any other of the G
possibilities given that we are in this region.
On this sort of account, there might be many apparent universals that
have no deep cognitive grounding and are nonetheless pervasive. Don’t get me
wrong, I am not saying these exist, only that we really have no knock down reason
for thinking they do not. And if
something like this could be true, then the fact that some property did or
didn’t occur in every G could be attributed to the nature of the kind of PLD
our part of the G space makes available (or how this kind of PLD interacts with
the learning algorithm). This would fit with Anderson’s view: contingent yet
systematic and attributable to the properties of the PLD plus learning theory.
I don’t think that H (nor most
linguists) would find this possibility compelling. If something is absent from
7,000 languages (7,000 I tell you!!!) then this could not be an accident! Well
maybe not. My only claim is that the basis for this confidence is not
particularly clear. And thinking through this scenario makes it clear that gaps
in the existing language patterns/Gs are (at best) suggestive about FL/UG properties
rather than strongly dispositive. It could be our ambient PLD that is
responsible. We need to see the reasoning. Culbertson and Adger provide a nice
model for how this might be done (see here).
One last point: what makes PoS
arguments powerful is that they are not
subject to this kind of sampling skepticism. PoS arguments really do, if
successful, shed direct light on FL/UG. Why? Because if correctly grounded PoSs
abstract away from PLD altogether and so remove this as a causal source of
systematicity. Hence, PoSs short-circuit the skeptical suggestions above. Of
course, the two kinds of investigation can be combined However, it is worth
keeping in mind that typological investigations will always suffer from the
kind of sampling problem noted above and will thus be less direct probes of
FL/UG than will PoS considerations. This suggests, IMO, that it would be very good
practice to supplement typologically based conclusions with PoS style arguments.[3]
Even better would be explicit learning models, though these will be far more
demanding given how hard it likely is to settle on what the PLD is for any
historical change.[4]
I found H’s discussion of these matters to be interesting
and provocative. I disagree with many things that H says (he really is focused
on languages rather than Gs). Nonetheless, his discussion can be translated
well enough into my own favored terms to be worth thinking about. Take a look.
[1]
I say ‘apparent’ for I know very little of this literature though I am willing
to assume H is correct that these exist for the sake of argument.
[2]
Which does not mean that we have nice models of what better accounts might look
like. Bob Berwick, Elan Dresher, Janet Fodor, Jeff Lidz, Lisa Pearl, William
Sakas, Charles Yang, a.o., have provided excellent models of what such
explanations would look like.
[3]
Again a nice example of this is Culbertson and Adger’s work discussed here.
It develops an artificial G argument (meatier than a simple PoS argument) to
more firmly ground a typological conclusion.
[4]
Hard, but not impossible as the work of Kroch, Lightfoot and Roberts, for example,
shows.
