Logical Reasoning

PT107 · S3 · Q23 Several carefully conducted studies

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Several carefully conducted studies showed that 75 percent of strict vegetarians reached age 50 without developing serious heart disease.

Premise

75% of strict vegetarians reached age 50 without serious heart disease.

Intermediate Conclusion (can conclude)

Avoiding meat increases one's chances of avoiding serious heart disease.

Conclusion (Therefore)

People who want to reduce the risk of serious heart disease should not eat meat.

Evaluate

Since there are two conclusion indicators here, we should think about whether there are flaws occurring at each move.

Is there a flaw in going from , ?

We'll sure. First of all, how does the 75% compare to meat-eaters? This author seems to assume that some lower percentage of meat-eaters reach age 50 w/o serious heart disease. But what if it's also 75% (or even higher)?

So one flaw in drawing that first conclusion is simply an Incomplete Comparison. The author is acting like 75% is better than some similar statistic for meat-eaters, but she never provided that other statistic

However, even if we grant that meat-eaters have a worse stat (let's say only 65% of meat-eaters make it to age 50 without serious heart disease), does that make it fair to conclude that ?

No, because that would just mean that avoiding meat is correlated with lower rates of heart disease. We wouldn't know for sure whether that lower rate is being caused by the vegetarianism or if it could be explained a different way (maybe people who eat vegetarian are more likely to get more exercise than meat-eaters, and it's the extra exercise that is actually the thing lowering the heart disease risk).

So this second flaw in drawing the 1st conclusion is the famous Causal flaw. Just because there's a correlation between X and Y doesn't mean we can assume that "doing X increases your chance of Y".

What about the 2nd conclusion, the one in the final sentence?

Is there a flaw in going from to ?

Not really. That's more or less a restatement. If we've established that doing X increases your chances of Y, then it's pretty reasonable to say, "so if you want Y, do X".

Goal

It seems like they're probably going to be testing the initial move from Premise to Intermediate Conclusion. I wouldn't be shocked if they don't bother mimicking the "Final" Conclusion.

We're looking for an Incomplete Comparison (75% of vegetarians vs. ? % of meat-eaters) that then turns into a "correlation = causation" type Flaw.

23.

The flawed pattern of reasoning exhibited by which one of the following is most similar to that exhibited by the argument above?

The majority of people who
Bad Conclusion Match
This conclusion adds in a brand new concept (hiring more police officers to enforce speed laws). The original argument kept recycling the same two concepts: avoiding meat and heart disease.
1% picked this
Studies have shown that cigarette
Bad Evidence Match
The first premise already seems like a red flag, because it's not an Incomplete Comparison. In the original, they told us a statistic for vegetarians, but not for non-vegetarians. Here, meanwhile, they're giving us an actual head-to-head comparison: cig smokers vs. non smokers. In the original, there was no second premise. It went straight into an intermediate conclusion. Here, meanwhile, they're giving us a 2nd premise that actually provides causality as a fact.
21% picked this
The majority of people who
Bad Conclusion Match
This conclusion, like (A)'s, adds in a brand new idea (the government making coffee less accessible). The original argument had two conclusions, both of which were just reiterating the two concepts from the premise: avoiding meat and risk of heart disease.
4% picked this
Studies show that people who
Bad Evidence Match Weak Conclusion Match
The first premise is a red flag, because it's not an Incomplete Comparison. In the original, they told us a statistic for vegetarians, but not for non-vegetarians. Here, meanwhile, they're giving us an actual head-to-head comparison: don't exercise regularly vs. do exercise regularly. This problem with the answer is similar to (B). Also, the conclusion adds a new concept (doctors), whereas the original argument didn't. This problem is similar to (A) and (C).
4% picked this
Correct
Most people who exercise regularly
Why this is right
Well, structurally it has the best chance of matching, since it's the only answer choice with two conclusions, just like the original argument. Here, those are indicated by "this shows that" and "So". In the original, those were indicated by "we can conclude" and "therefore". Does it provide an Incomplete Comparison? Yes. It says that "most people who regularly exercise can handle stress", but it seems to assume that "most people who don't regularly exercise can't handle stress". Does it take that assumed similarity and then make some Correlation = Causation move? Yes. It goes from thinking that regular exercise is correlated with can handle stress to an Intermediate Conclusion that assumes that regular exercise is the cause of this ability to handle stress. It also replicates the final conclusion, which is not really flawed, but it's lovely to see such a good match. All three ingredients (the premise and the two conclusions) were focused on regular exercise and handling stress, just as all three ingredients in the original were focused on avoiding meat and risk of heart disease.
Skill tested: Parallel Flaw · how this choice captures the argument's function is the move to repeat next time.
70% picked this

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