2. IMMEDIATE AND MEDIATE INFERENCE.
It has been noted that a truth may be derived from a consideration of one or two antecedent judgments. To illustrate further: From the judgment, “All men are fallible,” we may derive the conclusion that “No men are infallible”; or, from the two judgments, “All men are fallible,” and “Socrates was a man,” we may readily inferthat “Socrates was fallible.” These two modes of inference take the names of immediate inference and mediate inference. Let us express these two kinds in equation form:
| I. | |
|---|---|
| Ordinary Form. | Equation Form, Using Initial Letters. |
| Antecedent judgment: All men are fallible. | All m are f |
| Conclusion: No men are infallible. | No m are i |
| II. | |
| First antecedent judgment: All men are fallible. | All m are f |
| Second antecedent judgment: Socrates was a man. | S was m |
| Conclusion: Socrates was fallible. | ∴ S was f |
Giving attention to the antecedent judgments of the second argument it is noted that the terms “f” and “S” are referred to the common term “m.” In logic this common term is known as the middle term. As there is but one antecedent judgment in the first argument there can be no common or middle term. The first argument is an illustration of immediate inference; the second of mediate inference. This suggests the definitions:
Immediate inference is inference without the use of a middle term.
Mediate inference is inference by means of a middle term.