#13 - If that insect is a bee, it can only sting once. It

[amowuya]

*Question removed due to LSAC copyright restrictions*

Hi, PS!
I remember that the indicator "only" introduces necessity part, except "the only".
I think the argument's relationships are that IIB--->SO (IIB=insect is a bee; SO=sting once) and IIB--->SO.
and the four argument parts are:
Premise: IIB
premise: SO
premise: SO
conclusion: IIB
answer A: the relationships are: ISS---> S; ISS--->S (ISS=it is spring; S= can not stop sneezing= sneeze)
Premise: ISS
premise: S (can not stop sneezing)
premise: S
conclusion: ISS
Am I right? I saw other explainations different and they thought that the argument' relationships are IIB-->SO; SO--->IIB. And the answer A follows this pattern of reasoning.

Also I'm confused about the indicator "only" 's function in answer D.

Can you help me please?
Thanks!

Wenting

[Adam Tyson]

Thanks for the question, amowuya! It looks like you started off on the right track here - the initial conditional premise is as you described it:

IIB SO

Be careful about that necessary condition - it is not that it DOES only sting once, but that it CAN only sting once. One and done - it stings and then can sting no more.

Two things then happen in the stimulus: 1) we are told that an insect only did sting once and 2) the author concludes that the insect is in fact a bee.

There are two major problems with that argument: 1) just because it DID only sting once doesn't prove that it CAN only sting once. Maybe it could sting again and just hasn't gotten around to it yet? 2) The author concluded that the sufficient condition (it's a bee) must have occurred on the grounds that the necessary condition appears to have occurred (and like I said in #1, we don't really know that the necessary condition occurred). That's basically a mistaken reversal. The presence of the necessary condition never proves the presence of the sufficient condition!

Your diagram for the latter part of the argument looks to be backwards; it should be SO IIB.

So, in reviewing the answer choices, you want to pick one that essentially makes a mistaken reversal, with the author concluding that the sufficient condition must happen on the grounds that the necessary condition may have happened. If we can also find that element of "can" vs "did", great, but if not then at least we want that reversal in our answer choice.

Answer A follows that pattern perfectly, as you diagrammed it: the necessary condition (can't stop sneezing) might be happening (we can't be sure - we only know that he sneezed, not that he can't stop), and he concludes that the sufficient condition (spring) must also have occurred. We have the reversal, and the lack of certainty about the necessary condition. Bingo!

Answer D is a weird one! I've given it a lot of thought, and I am still struggling with it. I think it could be something like this:

Needed to Ruin Roof One Thunderstorm

We can be sure this is not the right answer, because we have no reversal going on. The author didn't say that we had a thunderstorm, therefore the roof must be ruined.

I'll be honest and say that I am not sure that is the only, or the best, way to diagram answer D. Looked at holistically, ignoring the conditional indicators "only" and "needed", it seems to be saying that if there is one more thunderstorm then the roof will be ruined, but I can't get my head around the proper use of those indicators right now. However, I know I can eliminate that answer, because even diagrammed this way I still don't have a reversal going on. The author did not say the roof is ruined so we must have had a thunderstorm.

I'm eager to see if any of my wiser colleagues will chime in on the language of answer D here!

[amowuya]

Hi, PS
What does the word "only" function in the argument? Is it a part of the phrase "only sting once" or an indicator? If it is an indicator, why shouldn't the second part of argument be "IIB--->SO"? Or this part is not a conditional relationship but a cause-effect relationship.

Sorry, I'm confused. I find your explanation reasonable, but I still get stuck the word "only"...

Thank you!

[Jon Denning]

Hi Wenting,

Thanks for the follow up!

The word "only" is super important on the LSAT, as it's not only one of the most common conditional indicators around (indicating necessary/required conditions, as you note), but it also serves to be inherently limiting in its implications: to say "only" about something means that it's exclusive, with no exceptions. That makes it both powerful—it's very absolute—and somewhat fragile, since a single exception can disprove it!

Here it's not used to set up the conditions themselves, but rather to describe what's happening in the conditions as a numerical indicator of occurrences: a bee can sting only once (its upper limit, so to speak) and that insect stung only once (a straightforward count of stings).

And I think it's that second bit—"it only stung once"—that's causing some confusion.

Usually when "only" is used it's to tie two pieces together in a very strict way: "Only bees can sting," for instance, makes stinging exclusively limited to bees, where "only" indicates that "bees" is the necessary condition:

Sting Bee

But saying something "only stung once" doesn't link the pieces, but rather it just gives you a specific number of instances: exactly one. The linkage has to do with what the author believes that single sting means, which is that the insect is a bee. Diagrammed that idea looks like this:

One Sting Bee

Notice that it's the logical connection we care about, and not just the presence of a single word. In fact, "only" is pretty much useless here, since you'd have the same point made without it: "this insect stung me one time" is functionally identical in meaning to "this insect only stung me one time" ("only" in this case shows more a surprise/relief about not being stung more than it does an exclusive relationship, which is what we care about for diagrams).

So be aware of key indicator words on the LSAT, as they can be a big help, but don't become so reliant on them that you prioritize them over the logic and reasoning of what's actually being said. In the end the reasoning is, dare I say, the only thing that matters

I hope that helps!

[cgleeson]

Hi,
I am lost on this question that I thought (keyword being "thought") was easily diagrammed.

[Beth Hayden]

Hi C,

First of all, I want to refer you to Adam's post above, because I think it sums up this argument really well and goes into the nuance about the difference between saying a bee can only sting once, and that the insect did sting once (because maybe it has the ability to sting a second time and thus isn't a bee).

Setting that issue aside, the diagram is basically a mistaken reversal:

Bee (Can only) sting once
Stung once Bee

How did you diagram the stimulus? Is there anything specific about the reasoning that is causing confusion?

Let us know and I'm sure we can elaborate further for you!

Beth

[cgleeson]

Yes, Beth, your explanation helped and I referred to Adam's reply as advised. Makes sense, tricky stuff huh LOL
Thanks again,
Chris

Hi C,

First of all, I want to refer you to Adam's post above, because I think it sums up this argument really well and goes into the nuance about the difference between saying a bee can only sting once, and that the insect did sting once (because maybe it has the ability to sting a second time and thus isn't a bee).

Setting that issue aside, the diagram is basically a mistaken reversal:

Bee (Can only) sting once
Stung once Bee

How did you diagram the stimulus? Is there anything specific about the reasoning that is causing confusion?

Let us know and I'm sure we can elaborate further for you!

Beth

[unfairbear]

the way i diagrammed the argument was :

if Bee --> stings once.
i got stung once.
therefore: it was a bee.

i basically saw it as the logical flaw of necessary condition therefore sufficient condition and i thought id be able to use contrapositive to match the flaw.

D says:
roof ruined --> at least one thunderstorm.
~roof ruined
contrapositive gives:
no thunderstorm --> ~roof ruined.
~roof ruined
therefore: no thunderstorm.
symbolically:
~P--->~Q (~P: no thunderstorm, ~Q: ~roof ruined)
~Q
therefore: ~P

for A)
if spring --> cannot stop sneezing.
sneezed once.
therefore: spring.

the second premise does not align with the necessary condition, one sneeze is not continuance so symbolically the way i diagrammed it was:
P--->Q.
~Q
therefore P.

whereas i understood the stem to be:
P-->Q
Q.
therefore P
(just like answer choice D as I assumed its valid to take contrapositives when a condition is given)


i just thought precision-wise, D was more in line with the flaw.

[Jonathan Evans]

Hi, unfairbear!

Answer choice (D) is not flawed. It is logically valid.

Premise: T RR
Premise: RR
Conclusion: T

This follows from contraposition.

You've got the Mistaken Reversal for the conditional in answer choice (D) in your post.

You may have had difficulty with the expression "was needed to." This expression can be understood to mean "would have been sufficient to."

I understand the difficulty with the syntax here, but if you're in doubt, ask yourself, "is the author implying the only way for that roof to be ruined would be for there to be another storm?" The answer to this question is no. Instead, the author implies that a single storm would have been enough to ruin the roof.

I hope this helps!