Logical Reasoning

PT148 · S3 · Q18 Journalist: Scientists took blood samples

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Journalist: Scientists took blood samples from two large, diverse groups of volunteers.

Conclusion

A dislike of vegetables is in at least some cases genetically determined.

Evidence

In a study people were separated into a group that said they like veggies and one that said they didn't. Blood samples were taken. All the people in the veggie-hating group had a gene in common (gene X, we'll say).

Evaluate

Since the author is drawing a causal conclusion (in some cases X is determined by Y), we can use our Curious Fact / Explanation mindset.

Curious Fact ... why did all the people in the veggie-hating group have gene X in common?

Author's Explanation ... gene X causes them to hate veggies

On Flaw questions, we need to either criticize the author's failure to consider Alternate Explanations for the Curious Fact, or raise some possible objection that would make the Author's Explanation seem implausible.

If we were trying to contradict the author's conclusion, we'd be arguing the position of "dislike of vegetables is never genetically determined".

So we'd have to find some way to explain away why everyone in the veggie-hating group had this gene in common.

Goal

Look for an answer complaining that the author has overconfidently assumed one causal explanation for the evidence, even though others may exist, or an answer that gives us way to say that even though they all had a gene in common, the veggie-hating might not be genetically determined.

18.

The journalist's argument is most vulnerable to criticism on which one of the following grounds?

It presumes that all human
Too Strong Assumption: all
We cannot say the author needed to assume that 100% of human traits are genetically determined. We only talked about one trait, liking or disliking vegetables. And even for vegetable-hating, the author is only saying "in at least some cases" it's genetically determined.
1% picked this
It overlooks the possibility that
Not an Objection
The author doesn't need either of the groups to be representative because the conclusion is not speaking for any more-general group. If I see a 4th grader dunk a basketball, I'm allowed to conclude, "Thus, in at least some cases, a 4th grader can dunk a basketball". That doesn't mean I'm assuming he/she is representative of 4th graders. I can assume he/she is a total freak. They still prove that at least sometimes this can happen. Similarly, it doesn't matter whether these veggie-haters are average or oddballs. Either way, if gene X is causing their veggie-hating, then the author's conclusion is factually true.
5% picked this
It overlooks the possibility that
No Causality in Evidence
If an answer is structured overlooks the possibility that even when X is true, Y may still be true then it will be correct if and only if it matches like this: overlooks the possibility that even when [Premise is true], [Opposite of Conclusion] may still be true. This answer is saying, "even when one phenom always produces another phenom". We stop there and ask ourselves, "Was there a premise that said that one thing always produces another thing?" Nope. There was a premise that said "one thing always accompanies another thing" (gene X always accompanied the people in the veggie hating group) But produces is causal, and we don't have any causal language until the conclusion. This answer choice is trying to weaken this type of argument: Tickling a baby always makes them giggle. Since I just heard Terry's baby giggling, the baby must have just been tickled.
12% picked this
It overlooks the possibility that
Even if + Conclusion
It is always wrong to say "If Conclusion ... " or "Even if Conclusion". The former can't be used to strengthen and the latter can't be used to weaken. When we say "even if the conclusion is true, I have this other complaint", the other complaint is meaningless. You just awarded the case to your opponent. You granted them the truth of their conclusion. That's game over.
7% picked this
Correct
It takes for granted that
Why this is right
Did the author need to assume that the veggie-loving group does not also all have gene X? For sure! If the veggie loving group and the veggie hating group all have Gene X, then who would possibly think that Gene X was causing people to hate veggies? In order for something to be a Causal Difference-Maker, it has to be a difference! If we say "Sharon is a better figure skater than Leslie because Sharon has had lessons", then we're assuming that Leslie has not also had lessons. This type of argument pattern is known as Assumes a Difference. It's sometimes such an obvious / implied idea that it's hard for us to notice that it was missing. If I say, "Kevin's waffling between an iPhone and a Samsung. He should go with the iPhone since they're having a sale right now." we hear it implied that only iPhone is having a sale right now. They are special in this way; that's why I only mentioned them. But logically that doesn't count. Just because it's the only thing you've mentioned doesn't establish it's the only thing with that trait. Just because the argument only mentioned that the veggie hating group had gene X is common doesn't mean that the veggie hating group was special for all having gene X in common.
Skill tested: Flaw · how this choice captures the argument's function is the move to repeat next time.
75% picked this

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