HARNAD: Let me just ask a question which everyone else who has been faithfully attending these sessions is surely burning to ask: If some rules you have described constitute universal constraints on all languages, yet they are not learned, nor are they somehow logically necessary a priori, how did language get that way?
CHOMSKY: Well, it seems to me that would be like asking the question how does the heart get that way? I mean we don't learn to have a heart, we don't learn to have arms rather than wings. What is interesting to me is that the question should be asked. It seems to be a natural question, everyone asks it. And we should ask, why people ask it.
My feeling is that if, say, the Martian that I was imagining were to look at earthlings and investigate them he would have no reason to doubt that language is as much an organ of the body as the eye or the heart or the liver. It's strictly characteristic of the species, has a highly intricate structure, developed more or less independently of experience in very specific ways, and so on. It has all the general properties of an organ of the body.
Why does it seem so strange to us to think in those terms? In other words, why does it seem to us so strange to us to consider human beings in the mental aspects of their life as we consider any object of the natural world? Why is it so natural to insist on a dichotomy in accordance with which we treat the physical development of humans as belonging to the physical world, but not their mental development?
My own feeling is, that what we have here is an inversion of a historical tradition that really ultimately has religious and other roots. Traditionally it was regarded as impossible, for all sorts of reasons, to study the human soul by the method of science.
Now, what's interesting to me is, precisely within those tendencies in science that tried to be naturalistic, that tried to defend science against religions, barbarism and so on. Precisely in those branches of science the same curious refusal to deal with the facts persisted, so that the question you raise seems to pose an overwhelming paradox to an investigator. The problem seems overwhelming: to explain the growth of this particular mental organ, human language, through the interaction of a genetically determined system with experience, although analogous questions about other organs do not seem to arise with the same force.
I think the question arises in the case of language exactly as it does in the case of the eye, the heart or the sexual organs (to pick something that matures long after birth) and so on. There is every reason to suppose that this mental organ, human language, develops in accordance with its genetically determined characteristics, with some minor modifications that give one language or another, depending on experience. But than, one would say the same about any bodily organ as far as I can see.
Stevan R. Harnad
Department of Psychiatry
Institute of Mental Health Sciences
CMDNJ-Rutgers Medical School
Piscataway, New Jersey 08854
The problem seems to have to do with the process called "induction." Let us adopt a simple definition and let intuition supply the rest. Induction involves the extraction of information from certain inputs. It involves real time, an initial state in which certain information is demonstrably absent, and a final state in which the information is demonstrably present. In between is something very like trial and error. The extent to which this trial and error is constrained by factors other than pure chance is determined by initial conditions. Furthermore, the extent to which induction is constrained by factors other than pure chance is precisely the extent to which it is not induction. So anyone speaking about "pure" induction must have something else in mind, because according to the present definition, some sort of structurally constrained initial conditions must obtain if an initial state is to be specified at all.
There is no question but that the above definition strongly equates inductive processes with statistical processes. Alternative contenders will have to come forward and be equally specific.
Now, the central question that motivates such close scrutiny of induction: When is it incumbent upon a scientist to give an inductive explanation of an empirical phenomenon? Otherwise stated, what must be explained in terms of "how it got that way" (as opposed to what can be accounted for by a state description simpliciter)?
Of course, "a state-description simpliciter" is usually neither a simple nor a simplistic matter. For example, if such a description is not to be just an empty phenomenology, it must make reference to certain alternative states, not actual but "possible" ones, and the state description must specify the constraints that generate the actual states rather than the possible states. It is the rules that exclude or forbid the alternative-states which give power and substance to a generative state description.
Now to return to the question of what demands an inductive explanation rather than a "mere" (possibly generative) state description. Perhaps it would be simpler to state what does not demand an inductive explanation, for I suggest that what does demand such an explanation constitutes by far the larger class.
As an example of what does not require inductive explanation, I offer a reductio in the form of an absurd question: Surely it makes no sense to ask, in general, "how the universe 'learned' its laws"! The primary laws of physics (whatever they will ultimately turn out to be), as well as cosmological initial conditions, are the structural constraints on the "initial state" of the universe, and they are not to be accounted for inductively; and this for totally nonmysterious reasons -- logical, and methodological (if one can speak of a methodology of theoretical explanation).
Second, the "laws" of logic are themselves not to be accounted for inductively. They too are "givens."
But it seems to me the buck stops here. When we turn to cosmology, evolution, learning, and other statistical phenomena it makes sense, indeed it is quite necessary, to ask how a particular state of affairs "got that way"; indeed, how it "learned" (by trial and error) to be that way.
We may have a very elaborate and sophisticated state description of phenomena in the latter classes (viz. cosmology, evolution, etc.), even generative accounts that specify rules which exclude the empirically nonexistent but "logically possible" alternative states. And yet we are still entitled, in fact driven, to ask how (which is here synonymous with "why") things actually got that way.
It is quite likely that for a particular empirical phenomenon not all inductive questions will be answerable "in situ," so to speak; i.e., some properties (or rules) will be "given" as structural constraints as far as that particular phenomenon is concerned. But that only means that the inductive burden must be shouldered at some earlier point in real time.
For example, if a particular behavior is not learned by an organism in ontogeny, then it was "learned" by evolution. And if that is not the case either, then it must be due to some physical conditions. If these physical conditions were not themselves due to essentially statistical processes, then they are direct consequences either of physical initial conditions or of logical first principles. If, however, this final pair of constraints is to be the explanation, then something more than retroactive handwaving is surety called for. The simple absence of an acceptable inductive explanation at a particular time is (like Wang's "photograph" of the platypus not laying eggs, DISCUSSION, this annal) surely no ground for claiming that it is not possible. Either the causal link with physical initial conditions must be explicitly specified, or it must be logically demonstrable that an inductive account would be self-contradictory.
Very rarely, I claim, do empirical phenomena qualify to be exempted by either of the above criteria from being answerable to induction. Structural descriptions, and especially generative ones, can be very satisfying in themselves, particularly if they yield a challenging and elegant internal structure. But that does not render them immune to the question: "Yes, but how did they [i.e. the phenomena] get that way?"- if, that is, the description aspires to lay claim to some empirical validity.
Furthermore (and this is only conjecture now) I suspect that the alternative states, which are the real backbone of a generative-structural account, are the ones that could most stand some inductive scrutiny. After all, they are dangerously close to the "modal arguments" of philosophers, in which some "possible world" is deemed worthy of consideration (and even ascribed some ontological status) simply on the grounds that it seems logically possible. But "seems logically possible" is a pretty weak sort of claim to fame. Trisecting an angle and squaring a circle (to give analytical examples) "seemed to be possible" to many, and now it turns out that they are not (and never have been). Synthetic examples abound, too: according to current physical law, it is not possible for matter to travel faster than light, nor to know at once the electron's precise momentum and position, even though these phenomena seem perfectly possible. Moreover, the "possible worlds" in which one is imagining these putative possibilities invariably involve tampering with (tentative) primary physical laws and initial conditions, which may itself be no more feasible, from the point of view of designing alternative universes, than squaring the circle.
There are, in all likelihood, many systems-constraints, derivative from physical conditions, which one is in fact hopeless in seeking to imagine away. It is, for example, not a "remarkable coincidence" at all that certain biological organs, e.g. the eye, whether arrived at by parallel or convergent evolution, share a number of essential properties, in all organisms that possess them. These invariances are probably due to constraints upon the transduction of light as it occurs in the universe (as well as to certain optimization factors). The number of actual alternatives is strongly constrained, regardless of what our imaginations seem to tell us. And the design-principles of an eye are not derived by positing rules that exclude imaginary (as opposed to actual) alternatives, thereby generating the real eye, but by examining how evolution actually selected among the actual alternatives (by induction). He who asks what disqualified the imaginary alternatives is asking a question, not about visual physiology, but about optics, cosmology, and perhaps ultimately, logic.
There are certainly logical and methodological (and even empirical) problems with the classical theory of evolution. The logical problem -- of a kind of circularity -- can be telescoped in the phrase "the survival of the survivor." This formulation appears to offer neither information nor refutability. Furthermore, the historical methods to which one is constrained by evolutionary thinking present methodological limitations. Finally, the new "random drift" theories suggest that genetic change is not entirely under the control of "selection pressures," as was once thought. Nor is it often evident whether one is dealing with positive evolutionary selection or with more general systems-constraints. But all these limitations notwithstanding, evolutionary thinking is the only inductive approach to "received" biological states, and, to my knowledge, there appear to be no nonmagic alternatives. Hence it is incumbent upon any scientist who is studying a biological system, no matter how sophisticated, to be an evolutionist, and advert, at least in principle, to the question of "how it got that way."
It is explanations of the sort that are in principle refractory to an inductive account (in terms of ontogeny, phylogeny, and physics) which must be regarded with some suspicion. At best, their refractoriness may be due to logical or cosmological factors. But at worst it may be due to a modal fantasy which generates its own rules and is answerable to none. In such a case, one perhaps has grounds for concluding that such an approach is not dealing with the real world at all, not even as an alternative.