Validity and Soundness

Validity and Soundness

Say whether the following arguments are sound, valid but not sound, or invalid. The actual truth values of the premises are identified by (T) and (F). For this exercise, all the valid arguments exhibit the following structure:

If p then q.
p
q

If Lassie is a collie, then Lassie is a dog. (T)
Lassie is a collie. (T)
Lassie is a dog.
1. Invalid
2. Valid but not sound
3. Sound
If Fifi is a poodle, then Fifi is a dog. (T)
Fifi is a poodle. (T)
Fifi is a dog.
1. Invalid
2. Valid but not sound
3. Sound
If Snoopy is a dog, then Snoopy is a rottweiler. (F)
Snoopy is a dog. (T)
Snoopy is a rottweiler.
1. Invalid
2. Valid but not sound
3. Sound
If Brian can speak, then Brian is a rodent. (F)
Brian can speak. (F)
Brian is a rodent.
1. Invalid
2. Valid but not sound
3. Sound
If Gromit is a dog, then Gromit can fly. (F)
Gromit is a dog. (T)
Gromit can fly.
1. Invalid
2. Valid but not sound
3. Sound
If Max is a dog, then Max is a reindeer. (F)
Max is a reindeer. (F)
Max is a dog.
1. Invalid
2. Valid but not sound
3. Sound
If Toto follows the yellow brick road, then Toto will reach the Emerald City. (T)
Toto reaches the Emerald City. (T)
Toto follows the yellow brick road.
1. Invalid
2. Valid but not sound
3. Sound
If Underdog saves the world from evil, then Underdog is heroic. (T)
Underdog does save the world from evil. (T)
Underdog is heroic.
1. Invalid
2. Valid but not Sound
3. Sound
If Mr. Peabody is a dog, then Bullwinkle is a moose. (T)
Mr. Peabody is a dog. (T)
Bullwinkle is a moose.
1. Invalid
2. Valid but not Sound
3. Sound
If Benji is small and scruffy, then Benji is cute and lovable. (?)
Benji is small and scruffy. (T)
Benji will be hit by a car.
1. Invalid
2. Valid but not Sound
3. Sound

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