A syllogism can be distinguished from other syllogisms by its form, that is, the mood and figure of a syllogism.
A syllogism’s form is determined by the mood and figure of the argument.
On the one hand, a Mood refers to the kinds of propositions that syllogistic arguments contain, whether A, E, I or O.
On the other hand, a Figure refers to the position of the middle term in the premises.
Note that the validity or invalidity of the syllogism depends exclusively upon its form and is completely independent of its specific content or subject matter.
Example:
All Filipinos are humans.
All Cebuanos are Filipinos.
Therefore, all Cebuanos are humans.
The mood and figure of a syllogism can be easily known if the letter S, P, and M are used to represent minor term, major term, and middle term respectively. Thus, the above syllogism will have this:
S – Cebuanos
P – humans
M – Filipinos
Using now the letters corresponding for each term, the syllogistic skeleton of the syllogism can be represented as:
All M are P.
All S are M.
Therefore, all S are P.
The mood of the argument is AAA since the premises and conclusion are all universal affirmative.
As previously stated, figure refers to the middle term’s position in the premises. There are four possible positions of the middle term in the premises, namely, diagonal to the right (figure 1), vertical to the right (figure 2), vertical to the left (figure 3), and diagonal to the left (figure 4).
It is interesting to note that with the four basic statement forms (A, E, I, and O) and four ways of positioning the middle term, it is possible to construct 256 different syllogistic arguments.