Q22 - Since anyone who makes an agreement

[pinkdatura]

I have a difficulty to diagram this stimulus into A-->B formal logic, the factors look so similar to me, I am seeking help about this question, could anybody walk me through this one? Thx

[bbirdwell]

Here's how I would approach this question. First, diagram.

"anyone" = "everyone" = a sufficient condition, or the left side of the arrow, so to speak.

We have a chain of logic here -- a premise (1) used to support an intermediate conclusion(2), which is then used to support a final conclusion (3).
1. make an agreement --> obligated to fulfill terms
2. obligated to perform action --> agreed to perform action
3. legal obligation to perform = required to fulfill agreement

At this point, we can sort of see the connection between "agree" and "obligated." Let's simplify a bit more to make it clear:
1. agree --> obligated
2. obligated --> agreed
3. legal obligation = agreement

It's reversed logic, that's all! 1 does not logically lead to 2! This is the kind of stuff we've seen all over this test! It was just hiding in a cloud of unnecessary detail and confused wording.

So, in the correct choice, we want something to point to the improper reversal here, or say something about necessary/sufficient.

(A) "good consequences?" Out of scope! Eliminate.
(B) "obligations other than those resulting from agreements?" This is not something the argument does. In fact, the argument equates obligation and agreement. Eliminate.
(C) The premise is not, in fact equivalent to the conclusion, as we can see above. Eliminate.
(D) On a first pass, I would say "Ok," this has something about necessary/sufficient. I'm not 100% sure about the last part, but overall it sounds pretty good. And at that point, rather than thinking and thinking and thinking and trying to figure it all out, I would leave the choice and check out (E).
(E) Not even close. Eliminate.

So it must be (D), which I would circle and then move on...

[zainrizvi]

The first part of (B) does work because it assumes that there are no other reasons why someone would make an obligation, other than agreements made. This refers to the necessary/sufficiency component. If there were no other reasons why the obligation was made, you could say obligation -> agreed to perform action.


The part that is confusing me is the second part of both answer choice (B) and (D). I have no idea what tehy mean.

For (D), I don't see it saying that any obligation -> legal obligation.. I thought the argument was saying legal obligation -> obligation


Edit: oops the first part of (B) is wrong well. The author doesn't assume that there are other types of obligations, it assumes that there AREN'T other types of obligations other than those rseulting from agreements made

[bbirdwell]

Yeah this is a confusing one! Part of the confusion, I think, is the synonymity of "obligation" and "required."

The original looks something like this:
make agreement --> obligation to fulfill

Thus:
obligated to perform --> agreed to perform

Thus:
legal obligation to perform = required to fulfill agreement to perform

This final could further distilled to:
legal obligation = required to fulfill agreement

And further still, with the substitution of the word "obligated" for "required" so that the linkage between statements can be more easily viewed:
legal obligation = obligation to fulfill agreement.

Notice the last statement is an equation, not a conditional relationship. Also, notice in the final statement the appearance of the word "legal."

The word "since" in the first sentence indicates that the first part is a premise, and the second part is a (bad) conclusion drawn from that premise. The final part is then another statement based on that intermediate conclusion.

The final part of (B) that you mention discusses the motivation for agreeing. It's incorrect because the REASONS why the actions are performed is totally irrelevant. Only the DEFINITION of an agreement as an obligation and vice versa is relevant.

The second part of (D) matches the last part of the diagram above, where "obligations" and "LEGAL obligations" are equated.

[Emily-L]

Hello,
In the explanation for the reason answer D is correct, what I don't understand is where the necessary/suffiicient question has come in. I do see that there is a reversal of logic, they say agreeement-> obligation, therefore obligated-> agreed, which is the reverse. Is a mistaken understanding of necessary/sufficient implied in an illegal reversal of logic? Perhaps that's obvious, but I hadn't made that connection..

Thanks!
Emily

[ohthatpatrick]

Yes, you've nailed it!

Nec/Suff flaw just means that the author botched conditional logic, either by illegally reversing a conditional or illegally negating it.

LSAT doesn't ever actually use the words "illegal negation" or "illegal reversal". They just use paraphrases of Necessary and Sufficient to describe those errors.

Consider this example:
Every time John eats a cookie, he smiles.
I just saw him smiling, so he must have just eaten a cookie.

The author is reasoning
Smiling --> cookie

whereas the original conditional was
cookie --> smiling

So we could say that the author took something like "cookie", which was sufficient (left side) to guarantee smiling and acted as though it was required (right side) for smiling.

Similarly, if we had:
Every time John eats a cookie, he smiles.
He hasn't had a cookie today, so he must not have smiled yet either.

The author is reasoning
~Cookie --> ~Smile

whereas the original conditional was
~Smile --> ~Cookie

And so the same Necessary/Sufficient switcheroo language applies.

Note: the test will either describe these flaws in the abstract Nec/Suff language, or it'll just point out that
Smiling --> Cookie
was a bad inference by saying something like "fails to consider that other things might make John smile".

Hope this helps.

[Emily-L]

Big help- thanks so much!

[dean.won]

Yes, you've nailed it!

Nec/Suff flaw just means that the author botched conditional logic, either by illegally reversing a conditional or illegally negating it.

LSAT doesn't ever actually use the words "illegal negation" or "illegal reversal". They just use paraphrases of Necessary and Sufficient to describe those errors.

Consider this example:
Every time John eats a cookie, he smiles.
I just saw him smiling, so he must have just eaten a cookie.

The author is reasoning
Smiling --> cookie

whereas the original conditional was
cookie --> smiling

So we could say that the author took something like "cookie", which was sufficient (left side) to guarantee smiling and acted as though it was required (right side) for smiling.

Similarly, if we had:
Every time John eats a cookie, he smiles.
He hasn't had a cookie today, so he must not have smiled yet either.

The author is reasoning
~Cookie --> ~Smile

whereas the original conditional was
~Smile --> ~Cookie

And so the same Necessary/Sufficient switcheroo language applies.

Note: the test will either describe these flaws in the abstract Nec/Suff language, or it'll just point out that
Smiling --> Cookie
was a bad inference by saying something like "fails to consider that other things might make John smile".

Hope this helps.

I fully understand your example but i dont see how its analogous to the question unless we assume that
"Makes an agreement" = "agrees to perform an action"
Do these two statements really mean the same thing?

[bearknowsthetrooth]

I'm still confused about the second part of D. To me, it seems like the conclusion is saying "any legal obligation is an obligation to perform an action" rather than the answer choice: "any obligation to perform an action is a legal obligation."

[yuchenh]

I still don't understand why the second part of D is correct despite explanations have been given above. Christine.Defenbaugh could you please explain this one?

[logicfiend]

I'm definitely no LSAT expert and I only really understood this problem on review, but here are my two cents on the last part of (D) :

This is the last sentence of the argument:

"Hence, saying that one has a legal obligation to perform a given action is the same as saying that one is required to fulfill one's agreement to perform that action."

D says, "it takes for granted (assumes) that any obligation to perform an action is a legal obligation."

The last sentence in the stimulus is equating being required (or obligated) to perform an action as the SAME THING as having a legal obligation to perform an action. This is what the answer choice on (D) is capitalizing on.

In timed practice, I definitely didn't think about this last sentence too hard, as the argument clearly was making a sufficiency/necessary error. But upon review, it definitely seems to match up nicely with that last sentence. Does that help?

[christine.defenbaugh]

I still don't understand why the second part of D is correct despite explanations have been given above. Christine.Defenbaugh could you please explain this one?

Happy to oblige, yuchenh!

Logicfiend has already cut to the heart of it:

The last sentence in the stimulus is equating being required (or obligated) to perform an action as the SAME THING as having a legal obligation to perform an action. This is what the answer choice on (D) is capitalizing on.

When we say that two things are the same thing, or identical, we are in essence creating a biconditional relationship. This is one of the reasons that I caution students not to use the "=" sign casually when conditional relationships pop up - most of them are only one direction, and thus the "=" sign is inappropriate!

Here, the author's final conclusion makes a clear cut equation:
legal obligation = obligation

Since an equivalency is, by definition, a biconditional, this is essentially saying two things at once:
if legal obligation --> obligation
and
if obligation --> legal obligation

I'm comfortable that the first one is unflawed. If you are a grey cat, you are most assuredly a cat; if something is a legal obligation, it is clearly 'an obligation' of some sort. But the second one is troubling; the author has not proved that all obligations are legal obligations! Why can't there be social obligations, moral obligations, ethical obligations, etc, that aren't "legal obligations"? If there are such non-legal obligations, then it is flawed to set "legal obligation" and "obligation" equivalent to one another!

And that's the part of this that (D) raises! The argument is assuming that "if obligation --> legal obligation". The conclusion needs this to be true for the equivalency to work.

The confusing part is that the second half of (D) doesn't match the language of the conclusion precisely: the conclusion is an equivalency, while the flaw raised in (D) is only one side of the biconditional that equivalency creates. But it's that one part of the biconditional that is flawed!

Please let me know if this helps clear a few things up!