Fallacy of Four Terms - Reducing Terms

Reducing Terms

Sometimes a syllogism that is apparently fallacious because it is stated with more than three terms can be translated into an equivalent, valid three term syllogism. For example:

Major premise: No humans are immortal.
Minor premise: All Greeks are people.
Conclusion: All Greeks are mortal.

This EAE-1 syllogism apparently has five terms: "humans", "people", "immortal", "mortal", and "Greeks". However it can be rewritten as a standard form AAA-1 syllogism by first substituting the synonymous term "humans" for "people" and then by reducing the complementary term "immortal" in the first premise using the immediate inference known as obversion (that is, "No humans are immortal." is equivalent to "All humans are mortal.").

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Famous quotes containing the word reducing:

    Single acts of tyranny may be ascribed to the accidental opinion of a day; but a series of oppressions ... too plainly prove a deliberate, systematical plan of reducing us to slavery.
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