Similarly in EAO in figure 1, instead of arguing that the whole of C is excluded from A, we draw a conclusion which really involves a further inference, namely that part of C is excluded from A.
[Illustration]
No B is A. All C is B. .'. no C is A. .'. some C is not A.
§ 639. The reason why the canons have been expressed in so cumbrous a form is to render the validity of all the moods in each figure at once apparent from the statement. For purposes of general convenience they admit of a much more compendious mode of expression.
§ 640. The canon of the first figure is known as the Dictum de Omni et Nullo—
What is true (distributively) of a whole term is true of all that it
includes.
§ 641. The canon of the second figure is known as the Dictum de Diverse—
If one term is contained in, and another excluded from a third term,
they are mutually excluded.
§ 642. The canon of the third figure is known as the Dictum de Exemplo et de Excepto—
Two terms which contain a common part partly agree, or, if one
contains a part which the other does not, they partly differ.