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J L FUNDAMENTAL "DEEP STRUCTURE" MODEL INDUCTIVE PROCESSOR = ( INDUCTIVE GENERALIZATION; OR ABSTRACTION

Figure 3.8.- Inductive inference. to an output set that includes: ? a new or revised theoretical structure T*, ? a prediction P* derived from T*, and ? a set of quantitative or symbolic data D* which both agrees with P* and is the representation of D in T*; that is, D* = P* and D* is the mapping of D onto T* (Burks, 1946; Davis, 1972; Dewey, 1929, 1938; Fann, 1970; Frankfurt, 1958; Gravander, 1975, 1978; Hanson, 1958, 1961, 1965, 1967, 1969; Kuhn, 1957, 1970, 1977; Lakatos, 1970, 1976, 1977; Mead, 1934, 1938; Miller. 1973; Peirce, 1960, 1966; Simon, 1965; Toulmin, 1960, 1961, 1972; Van Duijn, 1961). Models play a far more important role than in just analytic and inductive inferences: In abduction, fundamental models of processes structuring the world enter directly into the inference. Such models sometimes are the component of a theoretical structure replaced or modified by the inference. Of course, not every replacement or revision of the theoretical structure involves model modification. Those abductive inferences which revise or replace such components as laws or generalizations take the model to be a premise of the inference. The input/output morphology of abductive inference is shown in figure 3.9.

Probably there exists a family of abductive inference species. However, all members of this family must bear many resemblances to one another. Two such family characteristics are particularly important. First, the logical impetus behind the transition from ? to T* is the ability of T* to explain data which T cannot. Second, the attainment of explanation involves a re-representation of information - i.e., T fails to explain D and T* explains D*, where D* is not D but rather the representation of D in T*. As Lakatos (1976) notes, "discovery" is a process in which a theory stated in language L fails to explain a fact; therefore, it cannot adequately be represented in L, so a theory stated in L must be found to explain it and allow its representation in />'.

Virtually all standard accounts of scientific investigation include analytic and inductive inferences as important components of the logic of science. Abductive inferences are not as widely accepted or understood. Nevertheless, numerous detailed analyses of actual scientific discoveries have demonstrated that there are inferences in these discoveries that are neither analytic nor inductive in nature (Gravander, 1975; Hanson. 1958; Kuhn, 1957; Lakatos, 1977; McMullin, 1978). Examination of these scientific discoveries establishes that the researcher involved in the discovery possessed a determinate set of initial information, including some existing theory and data contradicting a prediction of the theory, and that there is a detailed inference which takes this initial information as its premise and provides the discovery as a conclusion. Whether it is possible to prove that the scientists in question actually followed this inference step by step is irrelevant insofar as the present investigation is concerned. The analyses reported demonstrate the existence of a family of nonanalytic and noninductive inferences which produce new or revised theoretical structures as output. This demonstration constitutes an existence argument for abductive inference.

It cannot be emphasized too strongly that the analysis of actual scientific discoveries is valid only as an existence argument for abduction, not as a research program for mechanizing it. Investigations into the logical process