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Wednesday, January 11, 2017, edited for an entry on academia.edu on Tuesday, October 31, 2023
Preface
From a review of the Pirie text:
PIRIE, MADSEN (2006)(2015) How To Win Every Argument, Bloomsbury, London.
'False conversion takes place when we deduce from the fact that all cats are animals the additional information that all animals are cats. The converse of a statement made by exchanging the subject and predicate, is true in some cases, false in others. (106).
All rats are four-legged animals, means all four-legged animals are rats is obviously false. (106).
True conversion according to Pirie:
No innovative people are bureaucrats. Therefore, no bureaucrats are innovative people. (107).
False conversion according to Pirie:
Some journalists are not drunks, therefore, some drunks are not journalists. (107). Pirie states this may or may not be true, but cannot be deduced from this false conversion. (107).
Paul Edwards (Editor in Chief), The Encyclopedia of Philosophy, (Macmillan, 1972), Volume 3, pp. 170-1 and Volume 5, p. 37.
'As can be seen from the table, the E- and I-type propositions are equivalent to their converses, which means that conversion is a validating form of immediate inference for E- and I-type categorical propositions. In contrast, conversion is non-validating for the A- and O-type propositions. Hence, to commit the traditional fallacy of Illicit Conversion is to convert an A- or O-type proposition.'
'False conversion takes place when we deduce from the fact that all cats are animals the additional information that all animals are cats. The converse of a statement made by exchanging the subject and predicate, is true in some cases, false in others. (106).
All rats are four-legged animals, means all four-legged animals are rats is obviously false. (106).
True conversion according to Pirie:
No innovative people are bureaucrats. Therefore, no bureaucrats are innovative people. (107).
False conversion according to Pirie:
Some journalists are not drunks, therefore, some drunks are not journalists. (107). Pirie states this may or may not be true, but cannot be deduced from this false conversion. (107).
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S = Spaniards
P = Portuguese
(My add)
Fallacy Files
A All S is P, therefore All P is S No conversion
E No S is P, therefore No P is S Yes conversion
I Some S is P, therefore Some P is S: Yes conversion
O Some S is not P, therefore Some P is not S: No conversion
Fallacy Files
A All S is P, therefore All P is S No conversion
E No S is P, therefore No P is S Yes conversion
I Some S is P, therefore Some P is S: Yes conversion
O Some S is not P, therefore Some P is not S: No conversion
Some Spaniards are not Portuguese does not necessarily mean that some Portuguese are not Spaniards.
Cited
Paul Edwards (Editor in Chief), The Encyclopedia of Philosophy, (Macmillan, 1972), Volume 3, pp. 170-1 and Volume 5, p. 37.
'As can be seen from the table, the E- and I-type propositions are equivalent to their converses, which means that conversion is a validating form of immediate inference for E- and I-type categorical propositions. In contrast, conversion is non-validating for the A- and O-type propositions. Hence, to commit the traditional fallacy of Illicit Conversion is to convert an A- or O-type proposition.'
----
BLACKBURN, SIMON (1996) Oxford Dictionary of Philosophy, Oxford, Oxford University Press.
CONWAY DAVID A. AND RONALD MUNSON (1997) The Elements of Reasoning, Wadsworth Publishing Company, New York.
EDWARDS, PAUL (1972) (Editor in Chief), The Encyclopedia of Philosophy, (Macmillan, 1972), Volume 3, pp. 170-1 and Volume 5, p. 37.
LANGER, SUSANNE K (1953)(1967) An Introduction to Symbolic Logic, Dover Publications, New York. (Philosophy).
PIRIE, MADSEN (2006)(2015) How To Win Every Argument, Bloomsbury, London.
(Selected relevant notes, my add)
Madsen Pirie, How to Win Every Argument: The Use and Abuse of Logic (2006), pp. 74-6.
Charles Ives, Essays Before a Sonata, The Majority, and Other Writings, edited by Howard Boatwright (New York: W. W. Norton & Co., Inc., 1962), p. 77. Via: Howard Pospesel, Introduction to Logic: Predicate Logic (1976), p. 176.
The Encyclopedia of Philosophy, Paul Edwards, Editor in Chief (Macmillan, 1972), Volume 3, pp. 170-1 and Volume 5, p. 37.
