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Epistemology and Logic 29

reasoning have been made explicit. Consider:

All lazy students are underproducers.

Therefore, Tim is an underproducer.

(j) Sorites: A series of interlaced syllogisms in which the

conclusion of one syllogism becomes a premise of another,

so that the chain leads to a conclusion connecting the subject

of the first statement to the predicate of the last.

2. The conditional syllogism is so called because its
   initial premise is introduced by an “i f ’ clause— a condi­
   tional clause. This “i f ’ clause (called the antecedent) is
   followed by a “then” clause (called the consequent):
   If he goes to the game, then he cannot study.
   (antecedent) (consequent)
   Conditional arguments depend for their validity upon the
   proper application of a second premise, which must be in
   one of two modes:
   (a) Affirming the antecedent (modus ponens), in which
   the second premise affirms that the “i f ’ clause, the condi­
   tion, is true: “He goes to the game.”
   (b) Denying the consequent (modus tollens), in which
   the second premise denies that the “then” clause is true: “He
   can study.”

If he goes to the game, then he cannot study.

He goes to the game (modus ponens).

Therefore, he cannot study.

If he goes to the game, then he cannot study.

He can study (modus tollens).

Therefore, he does not go to the game.

Fallacies of the conditional syllogism occur when
either of these modes is violated. The fallacies are affirming
the consequent and denying the antecedent. For example, a
second premise saying “He cannot study” would not permit
a conclusion that “he does not go to the game”—because it
is possible that he cannot study for other reasons. And a
second premise saying “He does not go to the game” would
not permit a conclusion that “he can study”—because the
initial premise did not say anything about what might
happen if he does not go to the game...