Deductive Logic

Author: St. George William Joseph Stock

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.


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Chicago: St. George William Joseph Stock, "Chapter II. Of Deductive Inferences.," Deductive Logic in Deductive Logic (London: Longmans, Green, and Co., 1888), Original Sources, accessed April 20, 2018,

MLA: Stock, St. George William Joseph. "Chapter II. Of Deductive Inferences." Deductive Logic, in Deductive Logic, London, Longmans, Green, and Co., 1888, Original Sources. 20 Apr. 2018.

Harvard: Stock, SW, 'Chapter II. Of Deductive Inferences.' in Deductive Logic. cited in 1888, Deductive Logic, Longmans, Green, and Co., London. Original Sources, retrieved 20 April 2018, from