Q16 - Nuclear fusion is a process

[ericha3535]

I got this question right by using POE...
could someone help me why C is the right answer?

[ohthatpatrick]

This question is an awesome example of how a very simple LSAT pattern gets dressed up in fancy (scientific, in this case) clothing.

Let me give you a simple version of this argument and see how you want to weaken it:

An allergy to pine trees causes people to sneeze when they are near a pine tree. Recently, Bob sneezed. His friend Doris cited this evidence in support of her conclusion that they were near a pine tree.

p1: allergies to pine trees cause you to sneeze when nearby
p2: someone sneezed
Conc: nearby pine trees

What's the flaw? How would you weaken this?

We could say maybe something flew up Bob's nose and that caused him to sneeze. Maybe he's also allergic to dogs and there's a dog nearby. Maybe Bob sneezes every hour, on the hour.

Say, I tell you that Cause A ---> Effect B.
If we observe Effect B, can we safely conclude it was Cause A?

No, this is a reversal of logic (described formally as confusing Necessary for Sufficient).

If this were a flaw question, we could pick an answer that said
A) takes for granted that an effect that results from a certain process results only from that process

However, when we see Causal flaws in the world of Strengthen/Weaken, it's more likely that the test will Rule Out or Supply an alternative cause.

We know that fusion causes a release of helium-4.

These scientists observed helium-4 and concluded that fusion must have occurred. Well, maybe. But maybe something else caused the helium-4 to be found in the air of the chamber.

(C) supplies an alternative cause. The helium-4 was found in the air in the chamber because helium-4 (in that quantity) is always found in air. There's no "special" amount of helium-4, so there's no reason to believe that fusion occurred (which would have resulted in some "extra" helium-4).

=== other answers ===
(A) doesn't address any alternate cause for the helium ... other gases are out of scope
(B) doesn't address any alternate cause for the helium ... other byproducts of fusion are out of scope
(D) doesn't address any alternate cause for the helium ... how rapidly helium-4 breaks down is irrelevant to what caused it in the first place
(E) doesn't address any alternate cause for the helium ... other byproducts of fusion are out of scope

This problem is a good reminder to all of us to, upon reviewing a question, practice seeing the general "fact pattern" behind the specific story. The better we learn LSAT's fact patterns, the easier it is to see this ugly nuclear fusion problem as a simple Effect-therefore-Cause flaw.

Hope this helps.

[Mab6q]

I have a general question about the explanation provided above and what to do when we are given a causal relationship in the premise.

Here, as you noted above, we are given a cause:

fusion --> helium 4gas.

Now we are to take this as true because it was given in the premise. However, I won't to see how far we take such causal claims to be true. Are to assume, as LSAT authors do, that such cause is the only cause and that there can be no other effect. If so, then the explanation above would not seem be an adequate one. However if we don't accept such deductions, then wouldn't it mean that the causal claim would inherently still be flawed despite the fact that it occurs in the premise because the author assumes that one cause could produce that effect and no other effects could result from that cause?


I hope that made sense. I'd appreciate any help.

[ohthatpatrick]

I think I understood your question.

We are to take the causal claim as true, that X is sufficient to cause Y.

We do NOT have to go down the author's erroneous road of assuming that just because X causes Y that any time we see Y we know we had X.

The FLAW the authors are often making is assuming that this one potential cause is the only cause.

So we shouldn't join them in "accepting" that bad idea.

The causal claim isn't inherently "flawed". IT does not profess to be the only cause. The author just erroneously treats it as though it says that.

For example:
"Buying a woman flowers always makes her smile. I just saw my mom smiling, so clearly someone bought her flowers."

We can accept the truth of
"buying a woman flowers always makes her smile"
while rejecting the logic of
"I just saw my mom smiling, so clearly someone bought her flowers"

The causal claim is:
buy woman flowers --> smiles

The logic of the argument is
smiling --> someone bought her flowers

It sounded, in your question, like you were getting confused between the idea that we need to accept the author's PREMISES (correct, generally we do) and the idea that we need to accept the author's ASSUMPTIONS (incorrect, we do NOT have to accept those).

Hope this helps.

[Mab6q]

I think I understood your question.

We are to take the causal claim as true, that X is sufficient to cause Y.

We do NOT have to go down the author's erroneous road of assuming that just because X causes Y that any time we see Y we know we had X.

The FLAW the authors are often making is assuming that this one potential cause is the only cause.

So we shouldn't join them in "accepting" that bad idea.

The causal claim isn't inherently "flawed". IT does not profess to be the only cause. The author just erroneously treats it as though it says that.

For example:
"Buying a woman flowers always makes her smile. I just saw my mom smiling, so clearly someone bought her flowers."

We can accept the truth of
"buying a woman flowers always makes her smile"
while rejecting the logic of
"I just saw my mom smiling, so clearly someone bought her flowers"

The causal claim is:
buy woman flowers --> smiles

The logic of the argument is
smiling --> someone bought her flowers

It sounded, in your question, like you were getting confused between the idea that we need to accept the author's PREMISES (correct, generally we do) and the idea that we need to accept the author's ASSUMPTIONS (incorrect, we do NOT have to accept those).

Hope this helps.

That was exactly what I was asking Patrick, that you so much. You hit the nail on the head.