Evaluation of Arguments by Analogy:
Rules for Evaluation

The first rule is to consider the number and variety of the positive instances. In the case of an analogy where we have only a single instance, the key question to ask is whether increasing the number or variety would affect the argument.

In the analogy between reasoning and tennis, tennis is a physical skill, but the generalization is about all skills: physical, mental, social, and so forth. So we need to consider whether examples from the other categories would confirm the generalization.

The second rule is to look for disconfirming instances.

In the analogy between reasoning and tennis, can you find examples of skills that are not learned by practice? If so, this counts against the generalization that all skills are learned by practice.

Counteranalogies--in this case, similarities between logic and other types of skills that are not learned by practice--are one of the most effective ways of rebutting an argument by analogy.

The third rule is to consider the initial plausibility of a generalization, the plausibility that there could be a connection between subject and predicate--in this case, between S and P.

Given everything we know about skills, for example, it is quite plausible to think that they are acquired by practice.


Finding the middle term | Rules for evaluation

Evaluation of Arguments by Analogy

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