Reasoning Skills and Determining Causes Practice

Updated on Sep 29, 2011

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Reasoning Skills and Determining Causes Practice

Answer the following questions carefully.

  1. Is the following a logical causal argument? Why or why not?
  2. Halcyon Café used to be packed every Sunday night when A.B. Gomez was there to DJ. Since they hired a new DJ to replace A.B. Gomez, though, Halcyon empties out by Sunday afternoon after brunch—only a small crowd now shows up on Sunday nights. It must be that people don't like the new DJ.

  1. You have a small dog, and you decide to take her to the new dog run in your neighborhood on Monday morning. On Monday evening, your friend, who has just gotten a new puppy, asks if she can bring the puppy to your house to play with your dog. On Tuesday morning, you notice that you have several flea bites on your ankles. You conclude
    1. your dog picked up fleas at the dog run.
    2. your dog picked up fleas from your friend's puppy.
    3. either a or b.
    4. a and b.

Read the following scenario and then answer the questions that follow.

    It's spring and Carol has been having a sore throat fairly often. She notices that one the especially windy days, her throat hurts the most.
  1. Can Carol say with confidence that the wind is causing her sore throat?
  2. What other possible denominators could there be for Carol's condition?

Do any of the following causal arguments commit the post hoc fallacy?

  1. I used to drink four or five cups of coffee a day and I had lots of headaches. Now that I quit drinking coffee, my headaches are gone.
  2. After we got our new vacuum cleaner, our electric bills skyrocketed. That thing might as well suck the money right out of our pockets!
  3. Mandy started feeding her two-year-old an extra-fortified oatmeal for breakfast, and as a result, he's grown two inches in the last two months!
  4. I rode my bike to work every morning for two years and at night, I always got muscle cramps in my calves. Now that I am taking the bus, the cramps have disappeared.

Read the following carefully. Are any guilty of taking sides in the chicken or egg dilemma?

  1. People don't have family values anymore. That's because so many people get divorced these days.
  2. Since Linda started exercising, she feels a lot better about herself.
  3. There are so many computer manufacturers because the cost of computer technology is so low.
  4. Because Ed took a course in electronics, he has been to do a number of household repairs and improvements.


  1. Yes, this is a logical casual argument. Whether it's because there is a new DJ that doesn't have as big a fan base as the previous one, or whether it's simply because the people don't like the music that the new DJ is playing, changing the DJ is very likely to have caused the decrease in attendance on Sunday nights. You should consider, though, whether or not there have been other relevant changes in the café , like new hours, new management, or new prices.
  2. While all of these choices are possibilities, the best choice is d. Your dog could just as easily have picked up fleas from other dogs at the dog run as she could have from your friend's new puppy. Furthermore, since your dog is exposed to both situations on the same day, she could have picked up fleas both times.
  3. Carol can only say this with confidence if she has carefully checked for other possible common denominators. If nothing else happens on the days when she has a sore throat, then Carol can safely conclude that it's the wind.
  4. Carol's sore throat may have to do with allergies (indoor or outdoor), infected tonsils, extra stress, low humidity in the house or other possible factors.
  5. This seems like a reasonable argument, not a post hoc error. Part of what makes this logical is the general knowledge that caffeine can cause headaches in some drinkers as its effect wears off.
  6. Post hoc. Chances are that unless you vacuum every room every day and you have a big house, the vacuum cleaner won't have much effect on your electric bill. More likely, your utility company has raised your rates and/or you're simply using your other appliances more.
  7. Post hoc. Babies grow in fits and spurts. Maybe the oatmeal is helping, but there are too many other possible causes for this person to assume the growth is due to the fortified cereal.
  8. This seems like a reasonable argument, not a post hoc error. Part of the logic comes from the fact that bike riding works the calf muscles a great deal and could easily cause cramps.
  9. Guilty. It's just as easy to argue that "so many people get divorced these days because people don't have family values anymore." As with any social issue, there are certain to be multiple causes.
  10. Though it is possible to argue the reverse, it's pretty likely that Linda's exercise is indeed responsible for her increased self-esteem.
  11. Guilty. This is another chicken or egg dilemma. The low cost of technology could just as likely be the result of so many different companies working to develop more cost-effective products and procedures. This case needs further investigation.
  12. It is quite likely that because he took a course, Ed has learned to do things around the house. This is not a chicken or egg dilemma.
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