Considerations for computational theories of speaking
John Henry Clippinger · 1975
programming languages and simulated environments just to give us ideas about how such mechanisms might work. Certainly this is a reasonable strategy to pursue at this level of abstraction and experimentation. But when intent then becomes formulation of a computational model of some form of human activity, then I believe that there is a need to provide some theoretical or empirical justification for model. For example, if model is of a human interpreter of discourse, does model make same mistakes as people do, does it resolve ambiguity in same way, can it make similar inferences from discourse as people, etc.? To answer these questions requires considerably more empirical evidence than we currently have. The real issue here is accountability. For programming languages and technological applications of computational linguistics this is relatively easy to determine. But when intent is descriptive, that is, when a model is presented as representing some human intellectual skill or process, then issue of accountability becomes murky indeed. For it is not enough to say that it works, or that expert judges cannot distinguish model from real thing; Weizenbaum's Eliza program showed how easy it is to attribute powers to computer it 123 doesn't possess and Colby's indistinguishability tests have similarly shown gullibility of trained psychiatrists. Consequently there is a need on part of descriptive computational linguistics to both specify types of tasks a model of a speaker or listener should perform and in addition, to extent it is possible, manner in which they should be performed. The problem then becomes knowing what it is one is wanting to describe and account for. And this is no easy matter, for as Wittgenstein noted (Wittgenstein, 1953), the aspects of things that are most important for us are hidden because of their simplicity and familiarity (one is unable to notice something--because it is always before one s eyes). Chomsky makes a similar point (Chomsky, 1970) As native speakers we have a vast amount of data available to us. For this reason it is easy to fall into trap of believing that there is nothing to be explained, that whatever organizing principles and underlying mechanisms may exist must be as data is given. Traditionally linguists -Chomsky among them -have focussed upon grammatical aspects of language usebecause it was so and assumed that in accounting for generation of grammatical utterances that they have in some way described at least some of mechanisms involved in generation of human speech. But as Max Black (Black, 1970), and a number of sociolinguists have pointed out (Hymes, 1972; Labov, 1974) to be able to characterize grammaticality of a language with a finite set of rules does not mean that speakers of that language utilize such rules in their speaking. Therefore to my mind there is real question of value of such descriptions in accounting for either individual or collective use of language. Consequently when dealing even with most obvious of linguistic facts there is a need to consider more general role of language as a communicative, problem solving, and expressive medium. Similarly there is a need to characterize type of explanation being sought; whether we want to explain language behavior in terms of reasons and intentions, or whether we want to describe it extentionally, in terms of causes. This latter distinction is one which Toulmin (Toulmin, 1970), Radnitsky (Radnitsky, 1970), Dennett (Dennett, 1975) and Goffman (Goffman, 1974), make in their varius dicussions of types of explanations appropriate to human or social sciences. Taking Toulmin's argument for moment, causes are essentially like physical laws, as they are beyond our control, whereas actions done for reasons can be regarded as applications of procedures (methods of calculation, techniques, rituals, or other formalized modes of behavior) that we have learned during our life While ideally it may be possible to explain human language behavior in terms of causal descriptions, for example by neurological models, it is doubtful that this is type of description that computational linguistics is seeking. Rather appeal of computational approach is precisely in its capacity to characterize symbolic procedures that we use and have learned. If this orientation is accepted, then I believe that obvious conclusion to be made is that language behavior should be described and explained as a learned intentional activity. Going one step further, then, one of its goals should bethe explanation of various reasons and purposes for different types of linguistic behavior. However, to answer such questions satisfactorily requires a twofold description of reasons for a procedural action. For taken from a historical or diachronic perspective, a given procedure is created to solve a particular set of problems at a particular time; hence its existence or reason for being is set in time. However, same procedure may then again be used at some later time to achieve some other action perhaps unrelated to first, and therefore has a reason independent of its derivation. Consequently, reason a particular procedure was used can be explained in terms of reason for its coming into being, or in terms of immediate effect or result it was invoked to achieve. Psychotherapy is full of such cases: Why do you smoke? Because I was bottle fed or Because I like taste? Similarly, for example, in understanding a speaker's use of intensifiers or dubitatives it is important to know whether they have a specific local meaning or whether they are a part of some standard discourse style -either personal or cultural. For modeling purposes differences are important, as they entail differences in representation. III. CONSIDERATIONS FOR A COMPUTATIONAL THEORY OF SPEAKING So far we have established that that segment of computational linguistic research concerned with describing human speakers should take some initial steps towards saying more concretely what it is trying to account for. Certainly if we are going to evaluate a piece of research in this field, we should have some preliminary consensus as to what a successful model of speaking should be able to do. Likewise, there should be some common understanding as to types of descriptions and explanations that are being sought. Taking second question for moment, I think that one of unique contributions of a computationally based methodology to human sciences is its capacity to give formal and .teleological descriptions to complex forms of symbolic behavior. Therefore one of principal, if not inviolate, ingredients of a computational theory of speaking should be a computationally based methodology. This requirement would to my mind disqualify statistically based, and to a lesser extent, predicate calculus based, models. Furthermore, I feel that it is incumbent upon a modeler of human discourse to make 124 informed use of more advanced programming concepts, as problems resolved at this level eventually contribute a richer and more complete representation at purely descriptive level. For example, although notions such as frames, mini-worlds, demons, actors, pattern matching and like are essentially programming concepts, they do represent solutions or partial solutions to programming complex symbolic environments which in all likelihood are far simpler than those encountered by everyday speaker. Consequently a computational model of speaking requires these techniques and methods both technically and theoretically. Now finally what a computational theory of speaking should in part, at least, account for. To date we seem to know very little about types of mechanisms involved in creation, formation, and regulation of speaking (here also, is included discourse and conversation). And while it would certainly be reassuring to compartmentalize speaking as a clearly bounded activity, both sociolinguists and phenomenologists have effectively dashed that hope. Since we can't say what speaking is -if indeed it is any single thing (language does a disservice here), we can point out some of those things that people appear to do while speaking. It follows then that a model of human speaking should be able to do these too. Seven Thin~s Speakers Do I. People normally initiate a statement or a discourse out of a desire to be understood. They have some goal, or effect they want to achieve which they think speaking might facilitate. 2. Speakers alter what they are saying according to physical and social context in which they are speaking. This in turn affects what is said and how it is said. 3. Speaker's have models of to whom they are speaking. They shape their remarks according to how they feel they are going to be interpreted. They apparently monitor what they are going to say, often making mistakes and changing their minds as they are speaking. 4. Speakers make effective use of thematic organization of their conversations to direct interpretation, to specify role relationships, to qualify, intensify, and to amuse. 5. Speaking has a tone to it. Sometimes it is angry, other times placating. It can also be erudite, reverent, direct, evasive, sardonic, etc. 6. Speaking can also be stylized, having cultural and sub-cultural