Name ________________________   Critical Thinking Homework 3.

1. Circle the valid arguments. Cross out the invalid arguments

A.
If the British had caught and executed Benjamin Franklin in 1777, Benjamin Franklin would be dead. Benjamin Franklin is not dead, so the British did not execute Benjamin Franklin.

C.
If the British had caught and executed Benjamin Franklin in 1777, Benjamin Franklin would be dead. The British did execute Benjamin Franklin, so Benjamin Franklin is dead.

B.
If the British had caught and executed Benjamin Franklin in 1777, Benjamin Franklin would be dead. The British did not execute Benjamin Franklin, so Benjamin Franklin is not dead.

D.
If the British had caught and executed Benjamin Franklin in 1777, Benjamin Franklin would be dead. Benjamin Franklin is dead, so the British did execute Benjamin Franklin.

2. Circle the valid arguments. Cross out the invalid arguments

A.
Whales are fish.
Whales are not fish.
So cheese is a mineral.

C.
Whales are mammals.
Whales are fish.
Fish are never mammals.
So whales are fish.

B.
Whales are mammals.
Whales are not fish.
So cheese is not a mineral.

D.
Whales are mammals.
Fish are never mammals.
Whales are not fish.
So some whales eat fish. 

3. Circle the deductive arguments. Cross out the inductive ones.

A.
All whales are fish.
Willie is a whale.
Therefore Willie is a fish.

C.
All monkeys can fly.
George cannot fly.
Therefore George is not a monkey.

B.
The vast majority of whales live free in the ocean.
Willie is a whale.
Therefore Willie lives free in the ocean.

D.
Monkey aerodynamics make flight extremely unlikely.
Kong is a monkey.
Therefore Kong cannot fly.