Philosophy 1100: Introduction to Ethics
Exercise 4: Extra Exercise on the Concept of Validity
Due Date: Tuesday, October 8
Instructions
1. For each of the following arguments, indicate whether you think that the argument is valid or invalid.
2. In the case of syllogistic arguments – which typically involve
terms like “all”, “some”, and “no” – you may want to use the method of
Venn diagrams if you had any problem with the syllogistic arguments in
the original Exercise 4.
3. Similarly, In the case of hypothetical arguments – which
involve “if . . . then - - -“ statements – you may want to use the four
rules concerning when such arguments are valid or invalid if you had
any problem with the hypothetical arguments in the original Exercise 4.
1. Pizza eaters are cowards.
But some cowards do drink beer.
Therefore, some pizza eaters drink beer.
Valid
___ Invalid ___
2. If God
does exist, then death is not the end of an individual's existence.
Death is not the end of an individual's existence.
Therefore, God does exist.
Valid
___ Invalid ___
3. All cats are carnivores.
Some carnivores eat mice.
Therefore,
some cats eat mice.
Valid
___ Invalid ___
4. Everyone who has accepted the one true faith will go to heaven.
Some women will go to heaven.
Therefore, some
women have accepted the one true faith.
Valid
___ Invalid ___
5. If she kidnapped the lad, she's a vile villain.
But she did not kidnap the lad.
Therefore, she is not a vile villain.
Valid
___ Invalid ___
6. Fetuses are human beings.
All human beings have a right to life.
Therefore, fetuses have a right to life.
Valid
___ Invalid ___
7. Jerry Falwell was a born-again Christian.
Only born-again Christians go to heaven.
Therefore, Jerry Falwell went to heaven.
Valid ___ Invalid ___
8. All aphrodisiacs are expensive.
Celery is not an aphrodisiac.
Therefore, celery is not
expensive.
Valid
___ Invalid ___
9. Bill O’Reilly is a closet socialist.
No socialists ever criticize President Obama.
Therefore,
Bill O’Reilly never criticizes President Obama.
Valid
___ Invalid ___
10. You can't buy illegal drugs at the local store.
Aspirin, however, is not an illegal drug.
Therefore, you can buy aspirin at the local store.
Valid ___
Invalid ___