Analogies and Missing Premises

Abstract

I have in several different treatments of analogy claimed that analogies are a distinct type of argument and should not be regarded as a species of either induction or deduction. I've distinguished between inductive analogies and a priori analogies, but have resisted interpretations of analogy arguments which would render them either as requiring generalizing inductions or as presuming an implicit premise which, when added, would render them deductively valid. I My views on analogy have been influenced by those of John Wisdom who, in his unpublished Virginia Lectures, maintained that what he called arguments by case, or case-by-case reasoning, is the most basic type of reasoning. 2 But Wisdom's views are neither standard nor well-known. Many people are hesitant about accepting analogy as a distinct type of argument. Some go even further, not wishing to accept arguments based on analogy as being arguments at all. Susan Stebbing, for instance, once claimed that so-called arguments by analogy were merely rhetorical devices. 3 Few today are likely to adopt the view that arguments by analogy are not arguments at all. But the idea that analogies are not a distinct type of argument does seem plausible to many people. There are several variations on this theme. Analogies can be regarded as all being inductive arguments, as all being implicitly deductive arguments, or as either implicitly inductive or implicitly deductive, depending on the case. It is the third view which is addressed here. Some analogies give empirical evidence about an analogue instance, claim a primary subject instance is similar to the analogue in various respects, and then reach a conclusion predicting further similarities. Such arguments strike many people as having an inductive generalization as an unstated premise, and as thereby embodying an implicit enumerative induction. Thus they might wish to model an inductive analogy as: