Analogy

Analogy is a special kind of similarity (see Goldstone & Son, Chap. 2). Two situations are analogous if they share a common pattern of relationships among their constituent elements even though the elements themselves differ across the two situations. Typically, one analog, termed the source or base, is more familiar or better understood than the second analog, termed the target. This asymmetry in initial knowledge provides the basis for analogical transfer, using the source to generate inferences about the target. For example, Charles Darwin drew an analogy between breeding programs used in agriculture to select more desirable plants and animals and “natural selection” for new species. The well-understood source analog called attention to the importance of variability in the population as the basis for change in the distribution of traits over successive generations and raised a critical question about the target analog: What plays the role of the farmer in natural selection? (Another analogy, between Malthus’ theory of human population growth and the competition of individuals in a species to survive and reproduce, provided Darwin’s answer to this question.) Analogies have figured prominently in the history of science (see Dunbar & Fugelsang, Chap. 29) and mathematics (Pask, 2003) and are of general use in problem solving (see Novick & Bassok, Chap. 1 4). In legal reasoning, the use of relevant past cases (legal precedents) to help decide a new case is a formalized application of analogical reasoning (see Ellsworth, Chap. 28). Analogies can also function to influence political beliefs (Blanchette & Dunbar, 2001 ) and to sway emotions (Thagard & Shelley, 2001 ). Analogical reasoning goes beyond the information initially given, using systematic connections between the source and target to generate plausible, although fallible, inferences about the target. Analogy is thus a form of inductive reasoning (see Sloman & Lagnado, Chap. 5). Figure 6.1 sketches the major component processes in analogical transfer (see Carbonell, 1983 ; Gentner, 1983 ; Gick & Holyoak, 1980, 1983 ; Novick & Holyoak, 1991 ). Typically, a target situation serves as a retrieval cue for a potentially useful source analog. It is then necessary to establish a mapping, or a set of systematic correspondences that serve to align the