Analysis of Arguments by Analogy

Once we have identified the property that A and B are supposed to have in common--the property we're labeling S--we can put an argument by analogy into a standard format. This format includes an inductive step and a deductive step, and it allows us to evaluate the argument by using what we have already learned about induction and deduction.

To see how this works, let's continue with the analogy between tennis and reasoning.

The common property here is that both are skills, and the relevance of this property is that skills must be learned by practice.

Tennis is a particular instance in which a skill requires practice, and it serves as inductive evidence for a generalization about all skills; this generalization is then applied deductively to the case of reasoning.

The first step in the argument is the inductive one, supporting the generalization that all skills require practice. This generalization serves as a premise in the second step, which is deductive, a categorical syllogism.

That premise expresses the link between skills and practice, and without this premise, we have no basis for the conclusion.

The other premise says that reasoning is a skill--it states the property that makes reasoning similar to tennis.

Two items being compared:
   Logic and tennis

The respect in which they are similar:
   They are both skills

The consequence of the similarity:
   Being learned by practice


Inductive Part:

   INSTANCE:
   Tennis is a skill and tennis is learned by practice.

   GENERALIZATION:
    Therefore, all skills are learned by practice.


Deductive Part:

   1.   All skills are learned by practice.
   2.   Logic is a skill.
   3.  Therefore, logic is learned by practice.


Evaluation of Arguments by Analogy

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