Psychologist Karl Bühler distinguished three main functions of language, to which his student, the philosopher Karl Popper, added a fourth. Popper discusses this distinction in several places, most notably in The Self and Its Brain, and at greater length in Knowledge and the Body-Mind Problem: A Defense of Interaction. I think it is very useful. (I am no Popperian, but I find that Popper’s work is always interesting. The Self and Its Brain – a gigantic volume co-written with John Eccles – is unjustly neglected by contemporary philosophers of mind, and a great book to dip into now and again when one is looking for something different from the same old same old.)
1. The expressive function, which involves the outward expression of an inner state. Here language operates in a way comparable to the sound an engine makes when it is revved up, or an animal’s cry when in pain.
2. The signaling function, which adds to the expressive function the generation of a reaction in others. Popper compares it to the danger signals an animal might send out in order to alert other animals, and to the way a traffic light signals the possible presence of cars even when there are none about.
3. The descriptive function, which involves the expression of a proposition, something that can be either true or false. The paradigm here would be the utterance of a declarative sentence, such as “Roses are red,” “Two and two make four,” or “There is a predator in the area.” Notice that the latter example differs from an animal’s cry of warning in having a conceptual structure. A bird’s squawk might cause another bird to feel fear and take flight. What it does not do is convey an abstract concept like eagle, predator, or danger, and thus it does not convey the sort of propositional content that presupposes such concepts.
4. The argumentative function, which involves the expression of an inference from one or more propositions to another in a manner than can be said to be either valid or invalid, as when we reason from All men are mortal and Socrates is a man to the conclusion that Socrates is mortal.
If you remember our discussion of Fred Dretske some months back, you might note that the first two functions identified by Bühler and Popper correspond roughly to Dretske’s distinction between “natural meaning” and “functional meaning.” “Natural meaning,” it will be recalled, amounts to nothing more than an effect’s indicating the presence of its cause, as spots on the face indicate the presence of measles. There is no possibility of misrepresentation here, since an effect will “naturally” mean whatever it is that happens to cause it. Hence if the spots on someone’s face were caused, not by measles but instead by an allergic reaction of some sort, then that, rather than measles, is what they will “naturally” mean. Bühler’s and Popper’s “expressive function” seems more or less the same insofar as they appear to think that an effect (the sound of an engine, an animal’s cry of pain, or someone’s angry and spontaneous utterance of the appropriate expletive when stepping in something at the dog park) will “express” whatever inward state it is that happens cause it.
The possibility of misrepresentation (which was Dretske’s concern) only clearly enters the picture with the “signaling function,” just as it does, on Dretske’s view, with “functional meaning.” An internal state or utterance might “functionally” mean that such-and-such is present even when it is not present; similarly, it might in Bühler’s and Popper’s sense “signal” the presence of something (predators, cars, or the headache your wife claims she is having) even when that something is not really there.
Dretske is concerned to develop a causal (and thus “naturalistic”) theory of meaning or representation, and Popper allows that a causal theory might be given of the expressive and signaling functions of language. Hence Popper might have been willing to allow that a theory like Dretske’s is correct as far as it goes. (Though as I noted in the post on Dretske, there are problems with his account of “functional meaning,” and thus problems with the account he would give of the “signaling function” of language.)
But Popper also holds that there can in principle be no causal account of the descriptive and argumentative functions, and that attempts to develop such an account tend inevitably to collapse the distinctions between the functions of language and reduce the descriptive and argumentative functions to the merely expressive and signaling functions that the naturalist has an easier time dealing with.
The reason Popper takes the descriptive function to be inexplicable in causal terms (and the argumentative function too, insofar as it presupposes the descriptive function) is one I discussed in an earlier post. A further reason he takes the argumentative function to be inexplicable in such terms is one related to what our friend Victor Reppert and others call the “argument from reason.” (Here is part of Reppert’s exposition of the argument from The Blackwell Companion to Natural Theology, and here is William Hasker’s exposition from The Emergent Self. I have defended the argument from reason in chapter 6 of Philosophy of Mind and at pp. 242-45 of The Last Superstition.) I discussed the metaphysical picture Popper derives from these considerations in another earlier post.
Of course, that isn’t Bühler pictured above. It’s his high school econ teacher Ben Stein, taking attendance in the hit 80s philosophical comedy Karl Bühler’s Day Off.