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11.1 Induction and Deduction Revisited

Arguments are built on premises that are believed, or assumed, to be true.

Some premises we establish by deductive arguments that have preceded, but

very many of the premises on which we must rely cannot be established by

deduction. Our reasoning process usually begins with the accepted truth ofsome matters of fact, in David Humes phrase. To establish matters of fact

we must rely on reasoning that is inductive.

Induction thus provides the starting pointsthe foundationfor the rea-

soning that concerns us most. We reason to establish truths in our everyday

lives, to learn facts about our society, to understand the natural world.

Deduction is certainly powerful in enabling us to move from known (or

assumed) propositions to other propositions that those premises entail, but in

the search for truths with which our reasoning must begin, it is insufficient.

The inductive arguments with which we establish matters of fact differ

fundamentally from the deductive arguments that were the concern in Part II

of this book. One essential contrast between the two families of argument

(noted much earlier in our discussion of basic logical concepts, Section 1.5) lies

in the relation of the premises to the conclusion in the arguments of the two

great families. In deductive arguments, the claim is made that conclusions follow

with certainty from their premises. That claim is appropriate because anydeductive argument, if it is good, brings to light in its conclusion what was

already buried in its premises. The relation between premises and conclusion,

in deduction, is one of logical necessity. In every deductive argument, if it is

valid and if its premises are true, its conclusion mustbe true.

In inductive argumentsthe concerns of this chapter and those that follow

the relations between premises and conclusion are not those of logical neces-

sity. The claim of certainty is not made. The terms valid and invalid simply do

not apply. This does not mean that inductive arguments are always weak;sometimes they are very strong indeed, and fully deserve our confidence.

Analogical Reasoning11.1 Induction and Deduction Revisited

11.2 Argument by Analogy

11.3 Appraising Analogical Arguments

11.4 Refutation by Logical Analogy

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