Definitions of Formal Fallacies

Question 1

Affirming the Consequent

Answer 1

Faulty inference involving a conditional (if..then) statement. The “if..” clause is the antecedent and the “then…” clause is the consequent. One can never AFFIRM THE CONSEQUENT.

Fallacy usually takes this form: If x, then y. If y, therefore x.

Question 2

Denying the Antecedent

Answer 2

Involves conditional argument and it occurs when the advocate DENIES THE ANTECEDENT, and reasons as though that entitled the denial of the “then” clause.

Fallacy usually takes this form: If x, then y. If NOT x, then NOT y.

Question 3

Unstated Assumption/Faulty Enthymeme

Answer 3

A three-part logical structure (syllogism) that contains a major premise (fact or statement that can be verified by evidence), minor premise (general rule), and conclusion (claim). The fallacy occurs when a debatable premise is missing. The syllogism is links three terms.

General form:
A is B. (Major)
C is an A. (Minor)
Therefore, C is B. (Conclusion)

Question 4

Petitio Principii

Answer 4

Also known as “Begging the Question.” It occurs when the advocate attempts to “prove” her or his assertion with the assertion itself. It is a mere reinstatement of the conclusion.

Question 5

Faulty Dilemma (Black and White Fallacy)

Answer 5

Simply poses an “either-or” situation. Occurs when the advocate reduces the logical alternatives in an argument to two, his way or the wrong way. The advocate fails to take into account all possibility. Such reasoning generally occurs at the policy level of argument in two ways: A) With reference to defending one’s own policy, by asserting that this is the desirable cours of action while the other possibility is dysfunctional/counterproductive/disadvantageous. or B) with reference to attacking someone else’s asserted policy, asserting that an opponent’s proposal will result in one of two effects, both being undesirable.

Question 6

Non Sequitur

Answer 6

“It does not follow.” Occurs when an advocate draws a conclusion unrelated to the evidence which precedes it or draws a conclusion not related to the premises of the argument.

Follows general syllogistic form:
All A’s are B’s. C is A. Therefore, C is D.