Exercise A

Which of the following arguments is valid? Which is invalid?

1. • Socrates is a man.

   • All men are carrots.

   • Socrates is a carrot.

2. • Abe Lincoln was either born in Illinois or he was once president.

   • Abe Lincoln was never president.

   • Abe Lincoln was born in Illinois.

3. • If I pull the trigger, Abe Lincoln will die.

   • I do not pull the trigger.

   • Abe Lincoln will not die.

4. • Abe Lincoln was either from France or from Luxemborg.

   • Abe Lincoln was not from Luxemborg.

   • Abe Lincoln was from France.

5. • If the world were to end today, then I would not need to get up tomorrow morning.

   • I will need to get up tomorrow morning.

   • The world will not end today.

6. • Joe is now 19 years old.

   • Joe is now 87 years old.

   • Bob is now 20 years old.