Hint: 'You can have cake or pie' (you could have both)
What is an exclusive disjunction?
Hint: 'The light is on or off' (it can't be both)
Apply disjunctive syllogism: 'Either the butler or the gardener did it. The butler did not do it. Therefore...'
What is the standard form of a disjunctive syllogism?
A) If P then Q; P; therefore Q
B) Either P or Q; not P; therefore Q
C) All P is Q; all Q is R; therefore all P is R
D) If P then Q; not Q; therefore not P
What is an inclusive disjunction (inclusive 'or')?
A) Exactly one of the disjuncts is true
B) At least one of the disjuncts is true, possibly both
C) Neither disjunct is true
D) Both disjuncts must be true
What is an exclusive disjunction (exclusive 'or')?
A) Both disjuncts can be true
B) Neither disjunct can be true
C) Exactly one disjunct is true, not both
D) At least one disjunct must be false
'Either the exam is on Monday or it is on Wednesday. It is not on Monday. Therefore it is on Wednesday.' This is an example of:
A) Modus ponens
B) Modus tollens
C) Disjunctive syllogism
D) Hypothetical syllogism
In a valid disjunctive syllogism with an exclusive 'or,' if one disjunct is affirmed, what follows?
A) The other disjunct is also true
B) The other disjunct is false
C) Nothing can be concluded
D) Both disjuncts are false
Why can you NOT validly affirm one disjunct and deny the other in an inclusive disjunction?
A) Because inclusive 'or' means neither can be true
B) Because both disjuncts could be true simultaneously
C) Because disjunctions are always false
D) Because affirming is never valid
Which form is valid for a disjunctive syllogism with inclusive 'or'?
A) P or Q; P; therefore not Q
B) P or Q; not P; therefore Q
C) P or Q; P; therefore Q
D) P or Q; Q; therefore not P
In everyday language, 'You can have cake or pie' usually implies what kind of disjunction?
A) Inclusive — you may have both
B) Exclusive — you may have only one
C) Conjunctive — you must have both
D) Conditional — one depends on the other