1. Explain how each of these arguments is an example of the neglected common cause or cum hoc fallacy:
a. Since we instituted this policy prohibiting drug X, drug X use in our nation has dropped 20% per year. This shows that the policy is effective.
b. Every time it storms, the barometer drops. Storms must have a powerful effect on barometers.
c. The economy has been in a recession ever since the president took office. He’s clearly doing a terrible job.
d. Ice cream sales have tripled in the last three months, and crime rates have fallen substantially. We obviously need to keep selling lots of ice cream so that crime rates will drop.
2. Explain how each of these arguments is an example of the post hoc fallacy:
a. Every time I wear my Flyers jersey, the Flyers win. So, of course I’m wearing my Flyers jersey at tonight’s game, and they’re going to win!
b. If you leave meat out long enough, maggots will appear. So, meat produces maggots.
c. Whenever I drink coffee before an exam, I do well. So you should drink coffee before our final this morning.
3. What point does this graph make about the relationship between correlation and causation?
4. How might one gather a representative sample of illicit drug use or private sexual conduct? How might doing so be different from gathering data about bird behavior or human residential patterns? Explain in about 100 words.
5. Probabilistic reasoning is tricky. Imagine the following scenario, commonly called the Monty Hall problem. You’re on a game show, and you must choose one of the three doors in front of you. Behind one is a car and behind the others are goats. You get to keep whatever is behind the door you choose, so while goats are cool and all, you probably prefer the car. You pick a door, say Number 1, and the host, who knows what’s behind the doors, opens another door, say number 2, which has a goat. He then says to you, “Do you want to stick with door number 1, or change to door number 2?”
The question: Is it to your advantage to switch your choice? Explain your reasoning. (Your grade is based on how you think about this problem, not your final answer).
Afterwards, if you’re still interested, watch this video to learn more:
6. Describe the role that base rates play in this clip from The Simpsons:
7. Why is it so important to think carefully and critically about induction? Think back to the conversations you’ve had the last week, and give an example of a time when the ideas in this chapter would have been helpful (if you don’t have an example from the last week, think further back in time).