Deductive Logic

by George William Joseph Stock, M.A.

Part 3: Chapter 2

Additional Information
  • Year Published: 1888
  • Language: English
  • Country of Origin: England
  • Source: Stock, G. W. J. (1888). Deductive Logic. Oxford, England; Pembroke College.
  • Readability:
    • Flesch–Kincaid Level: 11.0
  • Word Count: 188
  • Genre: Informational
  • Keywords: math, math history
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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.

444. But the distinction between the two might be conveyed with at least equal aptness in this way—

An immediate inference is the comparison of two propositions directly.

A mediate inference is the comparison of two propositions by means of a third.

445. In that sense of the term inference in which it is confined to the consequent, it may be said that—

An immediate inference is one derived from a single proposition.

A mediate inference is one derived from two propositions conjointly.

446. There are never more than two propositions in the antecedent of a deductive inference. Wherever we have a conclusion following from more than two propositions, there will be found to be more than one inference.

447. There are three simple forms of immediate inference, namely Opposition, Conversion and Permutation.

448. Besides these there are certain compound forms, in which permutation is combined with conversion.