There are two different kinds of arguments for a Rationalist approach to the study of mind. The first, so far as I can tell, is virtually tautological. The second is quite substantive. What are they? I’ll try to lay them out in a couple of posts. This one here discusses the “tautology.”
The tautological version is well laid out in the Royaumont conference papers (here) and how they relate to the innateness “controversy.” I put the latter in quote marks because most of the participants (including and especially Fodor and Chomsky, the so-called hard core nativists) considered the idea that the mind has innate structure nothing a simple tautology. Indeed, this is how Fodor and Chomsky repeatedly refer to the “innateness hypothesis” (see e.g. 263, 268). It’s tautological that the mind (and brain) has structure and biases as without such there can be no induction whatsoever and it is taken for granted that biological systems are constantly inducing (viz. engaging in non-demonstrative inference). This said, it is interesting to re-read the discussions for despite this general agreement, there is lots of intellectual toing and froing. Why? Because as Chomsky puts it (see Fodor’s version p. 268):
What is important is not just to see that something is a “tautology,” but also to see its import. (262)
What’s the import, as Fodor and Chomsky understood things? That there is no “learning” without a set of given projectable predicates that undergird it. Or, more accurately, as Fodor puts it, “ the very idea of concept learning is confused” (143). And the confusion? Two related, but importantly different, concepts have been run together; concept acquisition (CA) and belief fixation (BF). Regarding the former, we have no theory of how concepts are acquired. What we have are theories of BF, which are, at the most general level, inductive logics of various kinds, which, by their nature, presuppose a given set of projectable predicates and so cannot themselves serve as theories of CA. Or as Fodor puts it:
…no theory of learning that anybody has ever developed is, as far as I can see, a theory that tells you how concepts are acquired; rather such theories tell you how beliefs are fixed by experiences – they are essentially inductive logics. That kind of mechanism, which shows how beliefs are fixed by experiences, makes sense only against the background of radical nativism. (144).
Fodor and Chomsky (and most of the other participants at the Royaumont conference I might add if the comments section is any indication) believe that the above is a virtual tautology. All theories of learning are selective (i.e. stories where the given hypothesis space proposes and the incoming experience disposes). Where tautology ends and (some of the) hard work begins is to specify the set of projectable predicates that are in fact biologically/cognitively given (i.e. the shape and content of the hypothesis space that BFers actually bring to the “learning” problem). To repeat, no given space of alternatives, no way for an inductive logic or theory of BF to operate. The account of what is given is (or is a very good part of) a theory of the relevant biases.
Fodor and Chomsky pull several important consequences out of this tautology.
First, that many positions confidently explored in the cognitive literature are strictly speaking incoherent as expressed. Fodor discusses the “Piagetian” view that developmental conceptual change is a learning process in which learning replaces earlier conceptually weaker stages with subsequent conceptually stronger ones. Fodor argues that this position is, very simply, conceptually untenable. It is not untenable that development involves a succession of stages where the ith stage is conceptually stronger than the ith-1 stage. Rather it is untenable that this development is a result of stronger concepts arising via induction (i.e. learning). Why, because for induction to be possible the conceptually stronger system has to be representable. But to be representable means that the concepts that represent it must be cognitively available (must already be in the hypothesis space). But if so, they cannot enter the hypothesis space by induction as they are already available for induction. So, development cannot be a matter of CA via learning.
Does this mean that we development cannot be a matter of stronger concepts being acquired over time? No. But it does mean that this process cannot be inductive (e.g. this scenario is compatible with “maturing” new concepts, just not learning new ones). Note too, that this is compatible with treating development as a matter of new belief fixation. But recall that BF implies that the relevant concepts are given and available for computational use. Or, as Fodor puts it:
…a theory of conceptual plasticity of organisms must be a theory of how the environment selects among the innately specified concepts. It is not a theory of how you acquire concepts, but a theory of how the environment determines which parts of the conceptual mechanism in principle available to you are in fact exploited. (151)
In other words:
…fixation of belief along the lines of inductive logic…is one that assumes the most radical possible nativism: namely that any engagement of the organism with its environment has to be mediated by the availability of any concept that can eventually turn up in the organism’s belief. The organism is a closed system proposing hypotheses to the world, and the world then chooses among them in terms explicated by some inductive logic. (152)
To repeat, Fodor and Chomsky and virtually all the participants at the Royaumont conference take this to be tautological (as do I). The only theories of learning we have are theories of BF and these theories all presuppose that the stock of possible acquirable concepts is given. Radical nativism indeed!
So far as I can tell, the logic that Fodor and Chomsky outlined well over 30 years ago has not changed. And, if this is correct, then the central problem in cognition, linguistics being a special case, is to adumbrate the relevant hypothesis space for any given domain. And the only way to do this is to investigate the acquirable in terms of the acquired and argue backwards. If BF is the name of the game, then what is presupposed had better suffice to deliver the concepts acquired, and once one looks carefully at what’s on offer, this simple requirement appears to rule out most of the most popular theories, or so Fodor and Chomsky (and I) would argue.
It is worth observing that this tautology was recognized by the great empiricist philosophers. In this sense, the blank tablet metaphor generally associated with their theories of mind is unhelpful at best and misleading at worst. The distinguishing mark of empiricism is not that the mind is unstructured (comes with no given hypothesis space) but that the dimensions of the hypothesis space are entirely sensory. On this view, admissible concepts are either sensory primitive concepts or Boolean combinations of such. This is a substantive theory, and, as Fodor notes, it has proven to be false. Or as Fodor in his characteristic elegant way puts it:
I consider that the notion that most human concepts are decomposable into a small set of simple concepts –let’s say, a truth function of sensory primitives – has been exploded by two centuries of philosophical and psychological investigation. In my opinion, the failure of the empiricist program of reduction is probably the most important result of those two hundred years in the area of cognition. (268)
As many of you know, Fodor has argued that not only is there no possible reduction to a small number of sensory primitives, but that there is very little possible reduction at all, at least when it comes to our basic lexical concepts. I personally find his arguments against reductions rather strong. However, whether one buys the conclusion, the form of the argument seems to me correct: if you want a restricted set of primitives then you are obliged to show how these can be used to build up what we actually observe. The empiricist restriction to a small base of sensory primitives failed to deliver the goods, therefore, it cannot be correct; it cannot be the case that our basic concepts are restricted to sensory primitives.
So, is nativism ineluctable? Yup. So what’s the fight between Rationalists and Empiricists about? It’s about two things: (i) the shape of the hypothesis space: what are the primitive projectable predicates and how do they combine to deliver more complex predicates (e.g. what are the basic operations, primitives and principles of UG) (ii) how, given this space, are beliefs fixed (e.g. what is the relation between PLD and G)? Everyone is a nativist when it comes to CA. This is not controversial (or shouldn’t be). Empiricists are nativists that believe in a pretty spare hypothesis space. Rationalists are happy to entertain far more complex ones. This difference has an impact on how one understands BF. I turn to this in the next post.
 The distinction between instructive and selective theories has a long history in the study of the immune system. Here is a useful summary. Fodor’s point, which seems to me to be entirely correct (and obvious) is that all current theories of learning are selectionist and hence presuppose a fixed innate background of relevant alternatives.
 There may be room, in addition, for accounts of how to use incoming data to update the information that guides a learners movements across the given hypothesis space. What kinds of evidential thresholds are there, how many competing hypothesis does one juggle at once, what are the functions that in/decrease a hypothesis’ credibility “score,” how many “kinds” of evidence are tabulated at once, does the credibility function treat all hypotheses the same or are some more privileged than others, etc.? These are all relevant concerns. But Fodor and Chomsky’s tautological point is that they all are secondary to the issue of what does the hypothesis space look like.
 This conclusion is still resisted by many. See for example, Gallistel’s review of Sue Carey’s book here.
Others also seem to misunderstand the import of this. For example Amy Perfors (here) claims that Fodor’s point is “true but trivial” (132). This is taken to be a critique, but it is exactly Fodor’s point. As Perfors emphasizes: “…any conception which relies on not having a built-in hypothesis space is incoherent…” (128). This is a vigorous rewording of Fodor’s and Chomsky’s point. It is curious how often one finds strongly worded criticisms of nativist positions followed immediately with these criticized positions offered as novel insights by the very same author, in the very same paper.
 Once again some have confused the issues at hand. Perfors (see above) is a good example. The paper contrasts Nativism and Empiricism (127). But if everyone is a nativist with respect to the requirement that for learning to be possible a hypothesis space must be given, then everyone must be a nativist, in Fodor and Chomsky’s sense. The debate is not over whether we are nativists, but what kind of nativists we are (i.e. how rich a hypothesis space are we willing to tolerate). The contrast is between Rationalists and Empiricists, the latter limiting the admissible predicates and operations to associationist ones. And, as Fodor notes (see immediately below), this is what’s wrong with Empiricism. It’s not the nativism, but the associationism that makes empiricism a failed program.
 I hate to pick on the Perfors paper (well, not really) but it demonstrates how cavalier critics can be when it comes to positions that they consider clearly incorrect. The paper argues that Fodor’s critique can be finessed by simply understanding that one can have hierarchies of hypothesis spaces (132-3). Thus, contra Fodor, it is possible to treat elements of level N as decomposed of concepts of level N+1 and this gets all that Fodor criticizes but without the unwanted implicational consequences. Maybe. But oddly the paper never actually illustrates how this might be done. You know, take a concept or two and decompose them and show how they operate to license the wanted inferences and block the unwanted ones. There are lots of concepts around to choose from. Fodor has discussed a bunch. But the Perfors paper does nothing even approaching this. It simply asserts that conceptual hierarchies gets one around Fodor’s arguments. This is cheap stuff, really cheap. But sadly, all too common.