Evaluating Args

Here are the answers to the handout on evaluating arguments that we went over in class. Perhaps I should have titled the handout "So Many Bad Args!"

1) All bats are mammals.
All mammals live on earth.
All bats live on earth.

Overall Good (good structure and true premises)

2) All students in here are mammals.
All humans are mammals.
All students in here are humans.

Bad Structure (what if a dog were a student in our class?), so
Overall Bad (even though the premises are true)

3) (from Stephen Colbert)
Bush is either a great prez or the greatest prez.
Bush isn’t a great prez.
Bush is the greatest prez.

Questionable Premises, so Overall Bad (even though it has a good structure)

4) All students in here are humans.
Most humans are shorter than 7 feet tall.
Most students in here are shorter than 7 feet tall.

Bad Structure (there could be a lot of tall students in here even if most humans aren't tall), so Overall Bad (even though the premises are true)

5) Some people are funny.
Sean is a person.
Sean is funny.

Bad Structure (only some are funny, so I don't have to be funny), so Overall Bad (even though the premises are true)

6) If Sean sings, then students cringe.
Sean is singing right now.
Students are cringing right now.

False 2nd Premise (and questionable 1st premise), so Overall Bad (even though the structure is good)

7) All email forwards are annoying.
Some email forwards are false.
Some annoying things are false.

Questionable 1st Premise, so Overall Bad (even though the structure is good)

8) If Sean sings, then students cringe.
Sean isn't singing right now.
Students aren't cringing right now.

Bad Structure (students could cringe for a different reason) (and questionable 1st premise), so Overall Bad

9) All bats are mammals.
All bats have wings.
All mammals have wings.

Bad Structure, so Overall Bad (even though the premises are true)

10) If Sean sings, then students cringe.
Students aren't cringing right now.
Sean isn't singing right now.

Questionable 1st premise, so Overall Bad (even though the structure is good)

11) Some dads have beards.
All bearded people are mean.
Some dads are mean.

Questionable 2nd premise, so Overall Bad (even though the structure is good)

12) If Sean sings, then students cringe.
Students are cringing right now.
Sean is singing right now.

Bad Structure (I don't have to sing for students to cringe) and False 2nd premise (and questionable 1st premise), so Overall Bad

13) This class is boring.
All boring things are taught by Sean
This class is taught by Sean.

Questionable 1st Premise and False 2nd Premise, so Overall Bad (even though the structure is good)

(More on Sisyphus)