§ 439. Thus while deduction is concerned only with the relative truth or falsity of propositions, induction is concerned with their actual truth or falsity. For this reason deductive logic has been termed the logic of consistency, not of truth.
§ 440. It is not quite accurate to say that in deduction we proceed from the more to the less general, still less to say, as is often said, that we proceed from the universal to the particular. For it may happen that the consequent is of precisely the same amount of generality as the antecedent. This is so, not only in most forms of immediate inference, but also in a syllogism which consists of singular propositions only, e.g.
The tallest man in Oxford is under eight feet.
So and so is the tallest man in Oxford.
.'. So and so is under eight feet.
This form of inference has been named Traduction; but there is no essential difference between its laws and those of deduction.
§ 441. Subjoined is a classification of inferences, which will serve as a map of the country we are now about to explore.
Inference
________________________|__________
| |
Inductive Deductive
_________________|_______________
| |
Immediate Mediate
___________|__________ ______|______
| | | |
Simple Compound Simple Complex
______|________________ | ______|_____________|_
| | | | | | |
Opposition Conversion Permutation | Conjunctive Disjunctive Dilemma
|
_________|________
| |
Conversion Conversion
by by
Negation position
CHAPTER II.
Of Deductive Inferences.
$ 442. Deductive inferences are of two kinds—Immediate and Mediate.
§ 443. An immediate inference is so called because it is effected without the intervention of a middle term, which is required in mediate inference.