A new logic / by Charles Mercier.

  • Mercier, Charles Arthur, 1852-1919.
Date:
1912
Catalogue details

Licence: In copyright

Credit: A new logic / by Charles Mercier. Source: Wellcome Collection.

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    without finding him,’ unless we invent such a major as ‘ In all cases in which every room in a house is searched without finding a person, that person is not there.’ This is manifestly not the process of thought by which the conclusion is reached. No such major would, in fact, be constructed by the most enthusiastic syllogiser, unless he wished to bring the syllogism into ridicule. The actual process of thought is very different, and is that indicated by the fourth Canon of Explication. Every thing inconsistent with the postulate may be denied. If I have searched every room in the house without finding him, it is inconsistent with this postulate to say he was there; and that he was there may properly be denied. ‘ Europeans differ from Asiatics, for the former are capable of self-government, and the latter are not.’ No syllogism can be con- structed to represent the course of thought by which this conclusion is reached from the premiss. If the argument is considered, it will be seen that the conclusion is attained directly from the single premiss, and that no major is required; unless, indeed, the fifth Canon of Explication is taken as a major. When two terms are postulated in inconsistent relations to a third, they differ from one another with respect to that third. There is an old example, first discovered by the Port Royal logicians, of a conclusion that is too manifest to be questioned, but that baffles all the resources of Traditional Logic to attain. It runs as follows:— The Persians worship the sun; The sun is an insensible thing ; . • . The Persians worship an insensible thing. This is not a syllogism, for it contains no Universal, and the middle term is undistributed. It is clear, however, that, for the purpose of the argument—that is, of what the Persians worship,—the sun is given equivalent to an insensible thing, and may therefore replace it in the first premiss. This replacement gives us the conclusion. Could any process be more simple, or more manifestly indicate the actual process of thought ? These examples are sufficient to establish my first two theses that there are many Compound propositions to which the syllogism cannot be applied : many inferences that it cannot attain ,