Unit 3

Question 1

A valid argument may have false premises (T/F)

Answer 1

True

All snakes are slimy. (false)
All cobras are snakes. (true)
Therefore, all cobras are slimy. (false)

Question 2

A valid argument may have a false conclusion (T/F)

Answer 2

True

All snakes are slimy. (false)
All cobras are snakes. (true)
Therefore, all cobras are slimy. (false)

Question 3

A valid argument may have false premises and a true conclusion (T/F)

Answer 3

True

All cats are birds.
All birds are mammals.
Therefore, all cats are mammals.

Question 4

A valid argument may have true premises and a false conclusion (T/F)

Answer 4

False - Since the conclusion of a valid argument follows from its premises, if the premises are true, the conclusion must be true also.

Question 5

A valid argument may have true premises and a true conclusion (T/F)

Answer 5

True

All felines are mammals.
All cats are felines.
Therefore, all cats are mammals.

Question 6

A sound argument may have false premises (T/F)

Answer 6

False - A sound argument must have true premises.

Question 7

A sound argument may have a false conclusion (T/F)

Answer 7

False - A sound argument must have true premises, and its conclusion must follow from its premises, so its conclusion must also be true.

Question 8

A sound argument may have false premises and a true conclusion (T/F)

Answer 8

False - A sound argument must have true premises

Question 9

An invalid argument may have true premises and a true conclusion (T/F)

Answer 9

True - If the premises and conclusion are both true, then the argument would also be sound.