Examination Questions And Answers English Work Sheet (Page 2 of 7) in pdf

Examination Questions And Answers English Work Sheet Page 2

10. Suppose you know every member of a set of sentences is false. Can you tell from

that whether the set is inconsistent? (Defend your answer.)

I. ANSWERS

1. a.

No, the first premise is false.

True.

Valid.

No, since a sound argument is an argument that is valid and has all true

premises, but this argument has a false premise.

2. a.

Yes.

True.

Invalid, since it is possible that the first two premises are true but the

conclusion is false (for example if George Bush were an independent).

No, since a sound argument is an argument that is valid and has all true

premises, but this argument is invalid.

3. You can’t tell anything about its premises. For instance, the valid argument “If

Socrates is a man then Socrates is mortal. Socrates is a man. Therefore, Socrates is

mortal”, has a true conclusion and all true premises. But the valid argument “If

Koko (the gorilla) is a man, then Koko is mortal. Koko is a man. Therefore, Koko

is mortal”, has a true conclusion, and one true and one false premise.

4. At least one of the premises must be false since a valid argument cannot have all

true premises and a false conclusion.

5. If an argument is sound, then it is valid and has all true premises. If an argument is

valid then it is impossible for it to have all true premises and a false conclusion.

Therefore, the conclusion of a sound argument must be true.

6. No, both valid and invalid arguments can have all true premises and a true

conclusion. You would need to determine if it is also possible for the argument to

have all true premises and a false conclusion.

7. No, the conclusion of an invalid argument could be true or false. We only know

that in either case it will be possible for it to have all true premises and a false

conclusion.

8. No, the conclusion of an valid argument could be true or false. We only know that

in either case it will be impossible for it to have all true premises and a false

conclusion.

9. No, a person can have a consistent set of beliefs where one or more are false. If the

set is consistent, it only follows that it is possible for all set member to be true at

the same time.

Examination Questions And Answers English Work Sheet Page 2