Part III, Chapter 14: Of Enthymemes and of Enthymematic Sentences
WE have already said that an enthymeme is a syllogism perfect in the mind, but imperfect in the expression, since some one of the propositions is suppressed as too clear and too well known, and as being easily supplied by the mind of those to whom we speak. This way of reasoning is so common in conversation and in writing, that it is rare, on the contrary, to express all the propositions, since there is, commonly, one of them clear enough to be understood, and since the nature of the human mind is rather to prefer that something be left it to supply, than to have it thought that it needs to be taught everything.
Thus this suppression flatters the vanity of those to whom we speak, in leaving something to their intelligence, and, by abbreviating conversation, renders it more lively and effective. It is certain, for example, that if, of this verse from the Medea of Ovid, which contains a very elegant enthymeme: —
Servare potui perdere an possim rogas.
I am able to save, therefore, I am able to destroy thee, we were to make a formal argument in this way: —
He who is able to save is able to destroy;
Now, I am able to save thee;
Therefore, I am able to destroy thee.
All the grace would be taken away from it; the reason of this is, that as one of the principal beauties of discourse is to be full of meaning, and to furnish occasion to the mind of forming a thought more extensive than what is expressed, so it is, on the contrary, one of its greatest defects, to be void of sense, and to contain few thoughts, which is almost inevitable in philosophic syllogisms; for, the mind going faster than the words, and one of the propositions being sufficient to enable it to conceive two, the expression of the second becomes useless, containing, as it does, no new sense. This is what renders these kind of arguments so rare in ordinary life, since, without reflection even, we lay aside that which wearies us, and confine ourselves to that which is actually necessary to make our meaning understood.
Enthymemes are, therefore, the ordinary way in which men express their reasonings, by suppressing the proposition which they judge will be readily supplied; and this proposition is sometimes the major, sometimes the minor, and often the conclusion, although, in this last case, it is not properly called enthymeme, the whole argument being, in some sort, contained in the two first propositions.
It happens, also, sometimes, that we include the two propositions of an enthymeme in a single proposition, which Aristotle calls, for this reason, an enthymematic sentence, and of which he furnishes the following example: —
ἀθάνατον ὀργὴν μὴ φύλαττε θνητὸς ὤν, —
Mortal, cherish not immortal hatred.
The entire argument would be —
He who is mortal ought not to cherish an immortal hatred; Now, you are mortal; Therefore, &c. And the perfect enthymeme would be —
You are mortal, let not your hatred, therefore, be immortal.