Q11 - Biologist: Many paleontologists have suggested

[ohthatpatrick]

I would caution you against trying to initially see the flaw here as a conditional logic issue, despite the fact that the answers ultimately express the flaw in nec/suff language.

The first sentence says that some people think the difficulties of the ice age caused the human brain to evolve.

What you would ideally be thinking of now is not conditional logic flaws, but causal flaws (although some causal flaws are conditional logic flaws)

The way you diagrammed it, "Evol. HB --> Diff Ice Age", is not a fair way to represent that first sentence. Your diagram says that "for the human brain to evolve, it is NECESSARY that there are difficulties due to an ice age" .... the paleontologists are saying the reverse order, that the difficulties of an ice age were sufficient to cause evolution of the human brain.

The easier way to think about translating this is
Cause ---leads to--> Effect.
Hence, we'd represent it as
Difficulties of Ice Age ---> Evol. Human brains

The author concludes this view is wrong, that the Ice Age could NOT have caused the human brain to evolve.

Why? Because the Ice Age didn't cause brains to evolve for most other animal species.
Difficulties of Ice Age --/--> Evol. other brains

These two thoughts, however, do not contradict each other. They're compatible. Nerdy comic books might cause Ellen to be happy, even if nerdy comic books don't cause most people to be happy.

The author is trying to argue by analogy. Since most species did not have brain evolution as a result of the Ice Age, then humans must not have had brain evolution as a result of the Ice Age.

The best way to discuss or exploit the flaw in an argument based on an analogy is to demonstrate that the things being compared aren't "fair to compare"/ they're "importantly different" (you strengthen arguments based on analogies by doing the opposite, showing the things compared are relevantly similar)

Let's check out the answers. They have the off-putting abstract language that means we'll have to match up generalities with the specifics of this argument.

Remember that when Flaw answer choices start with
"neglects to consider", "fails to consider", "overlooks the possibility" etc.,
we should treat these ideas as Negated Assumptions (i.e., ask yourself "if this idea were true, would it hurt the argument"?)

When Flaw answer choices start with "takes for granted", "presumes", "assumes",
we should treat these ideas as Necessary Assumptions (i.e., ask yourself "was the author assuming this?")

(A) This answer describes Nec/Suff conflation (i.e. assuming that something Sufficient to produce an effect is also Necessary to produce that effect - as this answer says - or vice versa). The error of Nec/Suff conflation is when the author gives you a piece of conditional logic in the premise and then interprets it backwards in the conclusion. The easiest way to check for whether this type of flaw is the real flaw is to ask yourself, "was there a conditional statement in the premise?" If not, get rid of that answer. In this case, there is not. The premise is that "most species of animals didn't have their brains evolved in response to the Ice Age" ... "most" is never conditional.

(B) matching this up with our specific topic, this answer is saying that "the ice age could have produced brain evolution in human species even if it didn't produce brain evolution in other species". Does that weaken the argument? Yes!

(C) this is similar to (B), only now we're talking about a necessary condition, rather than a sufficient condition. Again, we would ask ourselves, "Was anything in the argument described as being NECESSARY to bring about a certain result? No." Thus, we can't match this to the argument.

(D) this is very tempting. I would have been thinking to myself, "the flaw here is equating how humans reacted to ice age with how most other species reacted. what if there was something importantly different about the human experience?" And this answer provides me with that sort of idea: humans had greater difficulties, hence they're not fair to compare to most other species, hence it's entirely possible the ice age caused their brains to evolve. There's just one problem with this answer: this idea Weakens the argument, but it's prefaced with the phrase "the author presumes". Would the author be assuming something that Weakens his argument? No. If this answer started with the phrase "fails to consider", "neglects the possibility", etc., it would be a correct answer.

(E) this sounds tempting because it describes the typical causal flaw: Correlation implies causality. This would describe an author who said:
"the human brain evolved after the end of the Ice Age. hence, the Ice Age caused the human brain to evolve."
Of course, our author disagrees with this, so this answer can't match.

Hope this helps. This is a tough question that brings up a lot of very heady LSAT issues, so please ask if you'd like me to clarify anything.


#officialexplanation

[LSAT-Chang]

I thought this question was by far the most confusing one from this section... I had no clue what the difference was between (B) and (C). Can someone help explain the difference between the two?? I could see that the flaw was an illegal negation of the statement.. so we have:

evolution of human brain --> difficulty to adapt to ice ages

then the biologist concludes from this that this MUST BE REJECTED because:

most animals with NO evolutionary changes to brain --> NOT difficult to adapt to ice ages

so what exactly is (B) and (C) referring to here??? and if I've misidentified the flaw, please correct me!

[LSAT-Chang]

I don't need ANY further clarification. Your explanation had way more than I could ask for. I don't know why I always thought "responsible" was a necessary condition. So if we had "A is responsible for bringing out B" for some reason, I think of it has "if B was brought out, then A was what brought it out" so B --> A, but I can see how it would be "A --> B" since we can think in terms of "A brought out B" so "if A occured, then B occured" -- the word "responsible" just confused me for a second.

[cacrv]

such a helpful explanation - thanks!!
I'm still hung up on B's "fails to address". Wouldn't "Overlooks the possibility" or "presumes without warrant" be better fitted for B? I got unnecessarily hung up on B and C because of this phrasing, even though I had a hunch C was wrong.

[at9037]

I still don't get why E is not the answer. Is it not the final conclusion that was drawn by the Biologist?

[ohthatpatrick]

By 'botanist', you mean the biologist / the author, right?

Her conclusion was "this suggestion must be rejected",
i.e. "difficulty of adapting to ice ages WAS NOT responsible for evolution of the human brain."
why?
other animals that adapted to ice ages didn't end up with evolved brains.

You're saying you can match up (E) with those two ideas?

[WenjiC19]

For this question, you have to assume that other animals had difficulties of adapting to ice age even though they eventually adapted to it.

[Laura Damone]

Agreed! When I first attempted this one I red-flagged the difficulty issue, too. Who knows, maybe other species found it easy to adapt. But upon closer thought, is it ever really easy to adapt to an ice age? Doubtful. And when something is objectively true, sometimes the LSAT will let you, even force you, to assume it in a challenging question like this.

Way to stay on top of it!