Read these sections to learn and apply a visual method for determining the validity of categorical inferences: Venn diagrams. Note the four categorical forms and what they mean: universal affirmative, universal negative, particular affirmative, and particular negative. Get comfortable drawing Venn diagrams for categorical statements and shading in the area or drawing a star for the statements you are given.
Complete the exercises, checking your answers against the answer keys, translating the diagrams into statements, and using the Venn test of validity to determine the validity of the given categorical inferences.
Exercise
Translate each of the following sentences into one of the
four categorical forms (universal affirmative, universal negative, particular
affirmative, particular negative). Make sure that the descriptions of the
two categories are nouns or noun phrases (rather than adjectives or
verbs).
- Real men wear pink.
- Dinosaurs are not birds.
- Birds evolved from
dinosaurs.
Chapter 2: Formal methods of evaluating arguments
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- Some mammals are not
predators.
- Some predators are not
mammals.
- Not all who wander are lost.
- All presidents are not
women.
- Boxers aren't rich.
- If someone is sleeping then
they aren't conscious.
- If someone is conscious
then they aren't sleeping.
- All's well that ends well.
- My friends are the only ones
that care.
- Someone loves you.
- Jesus loves everyone.
- Jesus loves the little
children.
- Some people don't love Jesus.
- Only pedestrians may use
the Appalachian Trail.
- Only citizens can be president.
- Anyone who is a Hindu believes in God.
- Anything that is cheap is no
good.
- Some expensive things are no good.
- Not all mammals have legs.
- There are couples without
children.
- There are no people who
hate chocolate.
- There are people who hate cats.
- Nothing that is sharp is safe.
- No poodle could run faster
than a cheetah.
- No professional runner is slow.
- Baboons aren't friendly.
- Pigs will eat anything.