Illicit major

from Wikipedia, the free encyclopedia

A logical fallacy in a categorical syllogism is referred to as Illicit Major or Illicit Major Term ( English for "prohibited generic term") , in which the generic term in the conclusion shows a distribution that is missing in the first premise.

cases

There are basically three cases in which the generic term is not distributed in the first premise. Accordingly, three cases of Illicit Major can be distinguished:

All M are O.

(1) All M are O. (O is not distributed)
(2) No U is M.
So: (3) No U is O. (O is distributed)

Examples

“All dogs are animals. Cats are not dogs. So cats are not animals. "

“All hot dogs are fast food. Hamburgers are not hot dogs. So hamburgers are not fast food. "

“All of the films with Jim Carrey are funny. There's no such thing as a horror movie with Jim Carrey. So there is no horror film that is funny. "

Explanation

In the first premise (“All dogs are animals”) there is no distribution for the generic term (animals) because it cannot be replaced by any sub-terms (marsupials, birds, artifacts) without jeopardizing the truth of the statement.

In the conclusion “Cats are not animals”, the generic term (animals) includes distribution because the truth of the statement can change if it is replaced by any sub-term of itself (e.g. dogs, pack animals).

Some O are M

(1) Some O are M. (O is not distributed)
(2) Some U are not M.
So: (3) Some U are not O. (O is distributed)

Example: “Some apples have maggots. Some pears do not have maggots. So some pears are not apples. "

Some O are not M

(1) Some O are not M. (O is not distributed)
(2) No M is U.
So: (3) No U is O. (O is distributed)

Example: “Some vehicles are not cars. No car is a bike. So no bike is a vehicle. "

For comparison: syllogisms without an illicit major

In all of the following cases there is no illicit major , all of these syllogisms are intact:


(1) All O are M. (O is distributed)
(2) Some U are not M.
So: (3) Some U are not O. (O is distributed)


(1) Some O are not M. (O is not distributed)
(2) Some M are not U.
So: (3) All U are O. (O is not distributed)


(1) No M is O. (O is not distributed)
(2) No U is M.
So: (3) Some U are O. (O is not distributed)

Individual evidence

  1. ^ Michael F. Goodman: First Logic . University Press of America, Lanham, New York, London 1993, ISBN 0-8191-8888-3 , pp. 73 f . ( limited preview in Google Book search).
  2. ↑ a b c Illicit Major. Retrieved July 18, 2020 .
  3. ↑ a b Illicit Major. Retrieved July 18, 2020 .
  4. ^ Michael F. Goodman: First Logic . University Press of America, Lanham, New York, London 1993, ISBN 0-8191-8888-3 , pp. 74 ( limited preview in Google Book search).