Syllogisms

Disciplines > Argument > Syllogisms

Syllogisms are arguments that take several parts, typically with two statements which are assumed to be true (or premises) that lead to a conclusion. This takes the general form:

Major premise: A general statement.
Minor premise: A specific statement.
Conclusion: based on the two premises.

There are three major types of syllogism:

• Conditional syllogism: If A is true then B is true (If A then B).
• Categorical syllogism: If A is in C then B is in C.
• Disjunctive syllogism: If A is true, then B is false (A or B).

Also of note for syllogisms is:

• Categorical propositions: Statements about categories.
• Enthymeme: a syllogism with an incomplete argument.
• Modus Ponens: If X is true then Y is true. X is true. Therefore Y is true.
• Modus Tollens: If X is true then Y is true. Y is false. Therefore X is false.
• Set Theory: The basics of overlapping groups.

Syllogisms are particularly interesting in persuasion as they include assumptions that many people accept which allow false statements or (often unspoken) conclusions to appear to be true. There is a difference between truth and validity in syllogisms. A syllogism can be true, but not valid (i.e. make logical sense). It can also be valid but not true.

See also

Syllogistic Fallacies, Conditional Reasoning, Cause-and-effect reasoning