If two things each resemble a third it is certain that they also resemble each other. If one thing equals a second, but does not equal a third, then the second and third do not equal each other.
In the syllogism two comparisons are made and the resulting agreement or disagreement is expressed in the conclusion. Thus:
Corrupt men are bad citizens.
Men buying or selling votes are corrupt men.
Therefore, men buying or selling votes are bad citizens.
Here the class of corrupt men agrees with the class of bad citizens; it also agrees with the class who buy or sell votes; now, as it agrees with each of the two classes, it is certain that those two classes also agree with each other. This is the plain form of the syllogism.
The following is an instance of disagreement:
Good citizens are patriotic men.
Traitors are not patriotic.
Therefore, traitors are not good citizens.