2. EPICHEIREMA.
An epicheirema is a syllogism in which one or both of the premises is an enthymeme. To put it in another way: An epicheirema is a syllogism in which one or both of the premises is supported by a reason.
When one premise is an enthymeme the syllogism is termed a single epicheirema; whereas when both premises are enthymemes it becomes a double epicheirema.
Single epicheirema.
All men are mortal, because all men die,
Socrates was a man,
∴ Socrates was mortal.
Double epicheirema.
All men are mortal, because all men die,
Socrates was a man, because he was a rational animal,
∴ Socrates was mortal.
It is obvious that supporting each premise with a reason lends strength to the argument. This justifies the use of the epicheirema.