Chapter 4
Logical Reasoning
Introduction
Deduction
Induction
Abduction
Analogy
Probability
Comparison
But the age of chivalry is gone. That of sophisters, economists, and
calculators has succeeded.
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Introduction
Sir, I have found you an argument; but I am not obliged to find you an
understanding.
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Logical reasoning is generally taken to include three specific types of
reasoning, deduction, induction and abduction. The chapter also discusses a
hybrid form of reasoning labelled inference, which is a means of proving facts
in a court. This chapter provides an outline of these methods of reasoning and
their use. It then compares them to highlight the major differences between
them. All of this is a prelude to more detailed discussion of the four forms of
reasoning in the next four chapters.
Deduction
Nature of Deduction
Deduction involves a form of argument known as a syllogism. It consists of a
major premise, a minor premise and the conclusion that follows from the two
premises.
To illustrate deductive reasoning, assume that Rule R says: ‘A cause B.’ This
can be the major premise of an argument. The syllogism then asserts in the
minor premise that the condition for the operation of the rule has occurred. In
our example the condition is the presence or happening of A. Then the
conclusion pronounces the consequences of the rule namely that “B occurs”.
This can be set out in a table in the following form:
___________________
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Edmund Burke Reflections on the Revolution in France (1790)
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Dr Samuel Johnson
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