QUESTION TEXT: Medical researcher: A survey of more than 1…
QUESTION TYPE: Flawed Reasoning
CONCLUSION: Mild sleep deprivation is probably healthy and boosts the immune system.
REASONING: People who sleep at least 8 hours a night have more diseases than those who sleep a lot less each night.
ANALYSIS: This argument confuses correlation for causation. Whenever there is a correlation, there are four possibilities:
- Sleep does cause illness.
- Illness causes more sleep.
- A third factor causes both illness and sleep.
- The correlation is a coincidence.
On a flawed reasoning question, the right answer will describe one of the other possibilities abstractly. Here, answer A describes the third possibility.
- CORRECT. This is possibility three above. Perhaps, for example, a weakened immune system causes more sleep (to repair the immune system) and more infections (because the immune system is weak).
- The argument didn’t say that only sleep affects health. There could easily be other factors, such as genetics, exercise, diet, etc.
- This is fancy language for taking a necessary condition to be a sufficient condition. That didn’t happen here.
- This is saying: if hammers can cause injury, then there will be a correlation between hammers and injury.
That’s flawed reasoning (hammer owners might be careful with their hammers), but it’s not the flawed reasoning used in the argument.
- This is a different flaw.
Example of flaw: Smoking doesn’t cause boils. Therefore, smoking is safe.
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