smoking teenagers

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smoking teenagers

by lukaswelker » Tue Apr 01, 2014 3:16 am
A study followed a group of teenagers who had never smoked and tracked whether they took up smoking and how their mental health changed. After one year, the incidence of depression among those who had taken up smoking was four times as high as it was among those who had not. Since nicotine in cigarettes changes brain chemistry, perhaps thereby affecting mood, it is likely that smoking contributes to depression in teenagers.

Which of the following, if true most strengthens the argument?
"¢Participants who were depressed at the start of the study were no more likely to be smokers after one year than those who were not depressed.
"¢the study did not distinguish between participants who smoked only occasionally and those who were heavy smokers.
"¢few, if any, of the participants in the study were friends or relatives of other participants.
"¢some participants entered and emerged from a period of depression within the year of the study
"¢the researchers did not track the use of alcohol by the teenagers.

Last three arguments are easily dismissed. But I can't see why the second one is not stronger then the first one. Any advice?

Many thanks,
Lukas
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by ceilidh.erickson » Tue Apr 01, 2014 7:09 am
This argument is an example of a common type of logical flaw: CORRELATION v. CAUSATION.

Premises:
- incidence of depression among those who had taken up smoking was four times as high as it was among those who had not
- nicotine in cigarettes changes brain chemistry

Conclusion:
- smoking contributes to depression in teenagers.

Logical Gap:
We observe smoking and depression happening at the same time (in other words, they are correlated). Whenever you see correlation in an argument, consider alternative causation models:
- Coincidence - what if there's no causation, and this just happened randomly?
- Outside Cause - what if some external factor (bad economy, war, etc) was somehow causing both the smoking and the depression?
- Reverse Causation - what if it's not the smoking causing the depression, but the depression making people more likely to smoke? This seems like the most likely alternative in this case.

To strengthen, we would need some piece of evidence that suggests either
a) it's not a coincidence,
b) they're not both caused by some 3rd thing, or
c) depression doesn't make people more likely to smoke



A. This is stating exactly what our "c" case was: the reverse causation is NOT what happened. Correct.

B. This is a very common wrong answer type. It makes distinctions within the category of smokers, but it doesn't allow us to connect smoking as a whole to depression. We don't care about various degrees of smoking - just "smokers" as an entire category.

C. Out of scope. If we thought "depressed people don't have friends," that would be adding a LOT of outside assumptions to the argument.

D. The argument is not concerned with how long people were depressed.

E. Alcohol is out of scope.
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Harvard Graduate School of Education

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by ceilidh.erickson » Tue Apr 01, 2014 7:17 am
Here's another example of CORRELATION v. CAUSATION:
https://www.beatthegmat.com/climate-v-s- ... tml#559011
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by BTGmoderatorAT » Mon Aug 28, 2017 5:44 am
End results in quitting smoking is changes in mood that leads to depression. It interferes with other parts of your life, like work, school, or relationships.