Phil Lieberman has written an important piece (here) (henceforth PL). It’s a reply to the Bolhuis, Tattersall, Chomsky and Berwick (BTCB) piece on Merge and Darwin’s Problem (discussed here). What makes Lieberman’s piece important is that it is an almost prefect example (being short not among its least attractive qualities) of the natural affinities that ideas have for one another. In this case, the following conceptions exert strong mutual attractions:
(i) Language as communication
(iii) Anti-modularity (i.e. cognition as general intelligence)
(iv) Gradualist conceptions of natural selection (NS) as the sole (or most important) mechanism of evolution
(v) Connectionist models of the brain. Though they may not strictly speaking imply one another, chances are that if you are attracted to one you will find the others attractive as well. Why is this?
Lieberman’s paper offers one line of argument that links these conceptions together. I would like to review these links here for I believe PL’s main message is important, precisely because it is wrong. As many of you may have noticed, I am of the opinion that Empiricism is a coherent, intellectually tight position with wide ranging (unfortunate) implications both for the study of language, mind and brains and for scientific methodology more generally. I believe that the degree that this is so is often underestimated. PL provides an example of its various strands coming together. I did not find the piece particularly persuasive, nor particularly well crafted. However, it is often in less worried versions of a set of ideas that one can more clearly see their underlying logic. PL offers us an opportunity to examine these. Hence the importance of the piece. So let’s dive in.
Concerning language, say you believe (iv) (as PL puts it: “Language evolved over millions of years”) then for NS to work its magic there has to be something common between our ancestors and ourselves. As it is evident that what "we" do with "language" is entirely different from what “they” do with it, to tell an NS story we need to find some common property between what we do and they do language wise that NS can focus on to get us from them to us. The only plausible common factor is vocalization with the common purpose of communication. So if you like (iv) you will naturally like (i). And vice versa: if you see language’s “primary role as communication” then you can see a way of understanding what we do as emerging from what they do given a sufficiently long time span (viz. million of years).
So, (i) and (iv) come as a bundle. Moreover, both of these suggest (iii). How so? Well ‘modularity’ is the term we use to mark a qualitative difference. The visual system is different in kind from the
visual (changed 2/16/15) auditory system. Each has its own specialized operations and primitives. Vision and audition are not reflections of some common “sensing” system. Thus, modules are
mental organs with their own distinctive and specialized properties (i.e.
properties that are not like those found elsewhere). But these are just the
kinds of things that NS per se is not
that good at explaining the origins of all
by itself. NS is good at finding the genetic gold among the genetic dross.
It in itself provides no account for how the gold got there in the first place.
In other words, given variation NS
can enhance some traits and demote others. However, this presupposes a set of
selectables and if what emerges is qualitatively distinctive from what came
before, then NS by itself cannot
account for its emergence. Some other source for the novelty needs to be found.
As modules are precisely such novelties, if you buy into (i) and (iv), then you
will also purchase (iii).
So no modules. But that strongly suggests that all cognition is of a piece. After all if they are not qualitatively different they are more or less the same (and NS and associationism love more-or- less-ism with all of its lovely hill climbing). In other words, the belief that the basic mechanisms of thought are effectively the same all over leads directly to (ii), associationism. What better universal cognitive glue than “imitation and associative learning”? So, we have paths that conceptually relate (i) and (ii) and (iii) and (iv).
A side note: The conceptual link between (ii) and (iv) has long been noted. For example, Chomsky commented on the common logic between NS accounts and classic associationism in his review of Skinner. Indeed, Skinner argued (as Chomsky noted) that one of the virtues of behaviorism, his species of associationsim, was its affinity with NS.
What’s the common core? Well, both NS and associationism are species of environmentalism. They share the common conceit that structure is largely a reflex of environmental shaping, a process that requires repeated environmental feedback to guide the process of evolution or learning (e.g. hill climbing with back propagation). In one case what’s shaped is the genome, in the other the mind. However both conceptions assume that the structure of the “inside” is a pretty direct function of the shaping effects of the outside. The common logic was recently detailed once again by Fodor and Piatelli-Palmarini (here). So it is not particularly surprising that aficionados of one will be seduced by the other, which means that those partial to (ii) will find (iv) attractive and vice versa.
So all that’s left is (v), and as Gallistel has shown, connectionism is just the brain mechanism of choice for associationism (see, e.g. here and here). So we can complete the circle. Starting from any of (i)-(v), we stand a pretty good chance of getting to all of the others. The link is not quite deductive, but the affinities are more than mildly attractive.
PL manages to add one more little bedfellow to this gang of five. These mutually supporting ideas also induce an adherent inability to distinguish Chomsky from Greenberg Universals. As I’ve been wont to note before (here), Empiricism and Associationism can plausibly accommodate the latter but not the former. And, right on cue, the PL paper makes the connection. Language variation (i.e. absence of Greenberg Universals) is taken to prove the impossibility of a Universal Merge operation (i.e. a Chomsky Universal). Thus, the PL paper argues that the fact that languages differ implies that they cannot be underlyingly the same, the presupposition being that identity/similarity in surface patterning is a necessary feature of a linguistic universal. If you are an Empiricist, it really is hard to see how to distinguish Chomsky from Greenberg.
There is much more nostalgic material in this little piece: Piraha makes a cameo appearance near the end (you could have predicted this, right?), as do FoxP2, Kanzi the bonobo, the Gardner chimps, and various unfounded assertions about the recursive properties of dancing. None of the claims are argued for really, simply asserted. However, given (i)-(v) you can construct (and then deconstruct) the arguments for yourself. The piece is not convincing, but, IMO, as convincing as it can be given its starting points.
BTCB reply to PL (here) and make all the obvious points. IMO, they are completely correct (but I would think this wouldn’t I?). BTCB identify a property of language that they want an evolutionary account for (viz. hierarchical discrete recursion (HDC)). They want to know how HDC of the kind we find in natural could have evloved. They note that this is not the only question relevant to the evolution of language, but it is a good question and a pretty good place to start. Curiously, this seems to be the one question that most EVOLANG types really don’t want to address. And it is clear why: it is the one that least (in the sense of 'not at all') lends itself to standard NS styles of explanation. It points to a cognitively distinctive species specific system whose properties seem sui generic. If correct (and right now there is no reason to think it is not) it argues that natural language really is cognitively different, at least in part. PL can’t believe this (why? See (i)-(v) above), as also seems to be true for most everyone else in the EVOLANG bidness. But it is, and that’s the main problem with PL’s little rebuttal. It fails to even recognize, let alone tackle, the hard EVOLANG problem: how did HDC arise?
To end: PL’s is a very useful paper. It is an object lesson in how ideas come in bunches and exhibit a certain logic and affinity. (i)-(v) above are particularly incestuous. PL’s paper exhibits these affinities. His argument is weak and that’s because (i)-(v) are wrong. And producing a very weak argument that exposes very weak premises is a very useful thing to do. PL has done us all a great favor in replying to BTCB. Take advantage of his generosity and learn.