A Logic of Facts; Or, Every-day Reasoning

by George Jacob Holyoake

All men |
Some men } are animals;
Socrates |
therefore
All men |
Some men } are mortal.
Socrates |

'To prove a negative, the argument must be capable of being expressed in this form:—

'No one who is capable of self-control is necessarily vicious;

All negroes |
Some negroes } are capable of self-control;
Mr. A.'s negro |
therefore
No negroes are |
Some negroes are not } necessarily vicious.
Mr. A.'s negro is not |

'Although all ratiocination admits of being thrown into one or the other of these forms, and sometimes gains considerably by the transformation, both in clearness and in the obviousness of its consequence; there are, no doubt, cases in which the argument falls more naturally into one of the other three figures, and in which its conclusiveness is more apparent at the first glance in those figures, than when reduced into the first. Thus, if the proposition were that pagans may be virtuous, and the evidence to prove it were the example of Aristides; a syllogism in the third figure,

Aristides was virtuous,
Aristides was a pagan,

therefore

Some pagan was virtuous,

Would be a more natural mode of stating the argument, and would carry conviction more instantly home, than the same ratiocination strained into the first figure, thus—

Aristides was virtuous,
Some pagan was Aristides,