Q14 - Ethicist: the general principle - if one

[ManhattanPrepLSAT1]

Question Type:
Necessary Assumption

Stimulus Breakdown:
The argument refutes a general principle that if one ought to do something, then one can do it. In support of this point it offers the example about promising to meet a friend though unable to do so because of a traffic jam.

Answer Anticipation:
"In order for the point about promising to meet a friend to serve as a counterexample it must meet two criteria:
1. Meeting the friend is something one ought to do.
2. Meeting the friend is something one cannot do."

Correct Answer:
(D)

Answer Choice Analysis:
(A) reverses the logic connecting meeting one's friend and being something one ought to do.

(B) undermines the argument, since relieving the obligation to meet one's friend undermines the first criterion.

(C) mistates the principle that is being undermined, but doesn't link the argument's evidence and conclusion.

(D) is correct. This must be true otherwise the example could not serve as a relevant counterexample to the principle in question.

(E) undermines the argument by suggesting that one's not being able to do something is inconsistent with having an obligation to do it.

Takeaway/Pattern: Reasoning Structure: Conditional Logic

#officialexplanation

[ch3014]

Can any instructor explain why answer choice A is wrong?

[LsatCrusher822]

Im not an instructor, but I can definitely help you with this one!

The stimulus here is basically trying to equate the example of a promise to be an obligation. If somebody made a promise to meet somebody at a certain time and can't do so because of a traffic jam, the stimulus argues that this is equivalent to making an obligation but not being able to fulfill it. But what if a promise and an obligation are two different things? D basically takes away this weakness. We have to assume that for the conclusion to be true, that an "obligation" is something that needs to be fulfilled. We need to apply the same criteria to a "promise" in order for this argument to work. If we take the contrapositive of D, "The obligation created by a promise IS relieved by the fact that the promise cannot be kept," then the argument falls apart. This is because then a promise is now NOT an obligation.

A) This would be correct if we reversed "ought" and "promised". Typically for a conditional to be a correct answer in an assumption question, the evidence needs to be in the sufficient portion of the answer choice, and the conclusion needs to be in the necessary portion. Our evidence was the example of a promise, while the obligation was the conclusion.

B) The argument doesn't talk about an exception or a limitation...
C) What about promise? This doesn't link the evidence to conclusion!
E) "should not have made the promise"... this is out of scope!

[ch3014]

Ok yeah that's what I thought about A too, until I thought about its contrapositive, which I believe is "if a person does something that s/he promises to do, then that person does something s/he ought to have done." But I think it's not necessary to take the contrapositive in this case since the person in the premise DOES FAIL to do something that he promises to do.

[Reesicup0815]

I am having quite a bit of trouble with this one. I actually got it right but not entirely sure why. I read the explanations posted above and I understand it except for one thing. When I read the Ethicist's statement, I don't see any clues that would indicate her actual position on an obligation not being relieved by failing to do what was promised. To me, it sounds like the argument is stating that it is understandable to occasionally fail to fulfill a promise/obligation. For example, "the unforseen traffic jam is not your fault, there was nothing that could have been done about it, so you cannot be held responsible for failing to meet your friend; as it was impossible to have physically been on time. " So I feel this is giving an example of one's obligation CAN BE RELIEVED in this particular type of example. Am I missing something? I don't want to miss a question like this on test day!!

[ohthatpatrick]

PRINCIPLE:
If you eat cotton candy, you will be happy.

Let's say I see that principle and argue, "Hey, that doesn't always hold true!"

What am I saying? What sort of counterexample do I have in mind?

Anytime you're arguing that a conditional rule is not true (this is the same as when you're negating a conditional statement, if for some reason you needed/wanted to do that), you are saying:
it's possible to HAVE the left side, but NOT have the right side.

I think it's possible to
eat cotton candy, but NOT be happy.

This Ethicist says that there are counterexamples to the rule:
"If you ought to do X, then you can do X."

So she must think it's possible that
you ought to do X, but you CAN'T do X

In her counterexample, she establishes that the person
CAN'T do X (impossible to keep your promise to meet your friend)

but she never establishes that
you ought to do X (you ought to keep your promise to meet your friend)

So that's all we're looking for in the answer choices:
This author is assuming that the person in traffic SHOULD keep their promise to meet their friend on time.

Or as (D) miserably puts it, the author assumes that "the promise is NOT invalidated by traffic jam" ... it's still binding.

[tw4jp]

I still have questions about A. Isn't A the contrapositive of " if you promise to meet a friend, then you ought to do so", hence it addresses the first part of the general principle?

[at9037]

From the above explanation I understood two things about the argument:

1) We have to assume that a promise to do something is the same as an obligation to do something.

2) Just because she could not do something does not mean she ought not.

But why are we assuming the second point? Also, how does answer choice C tie into the first and second point?

[ohthatpatrick]

I'm not sure what you meant by the 2nd point. I don't think we're ever saying "just because you could not, that doesn't mean you ought not."

The principle being debated is this:
"If you say that someone SHOULD do something, are you implying that the something is POSSIBLE for them to do?"

f.e. "If I say you ought to stand up to bullies, am I implying that you CAN stand up to bullies"?

The author is saying "Not always. Sometimes we're saying you ought to do something, even though we know you can't do it. Check out this example:
Person promised to meet friend at a certain time. Person got stuck in traffic jam and couldn't meet friend at that time."

In order for this example to be an instance where the principle doesn't hold, two qualities have to be true:
1. you ought to have done X
2. you could not have done X

If the author succeeds in establishing that, in a certain example, "you ought to have done X, even though you could not have done X", then the author has successfully proven that there are exceptions to the rule:
If you ought to do it, then you can do it

Since all these arguments are flawed, we have to figure out where the author fell short of establishing those two key components.
1. you ought to have met your friend on time
even though
2. you could not have met your friend on time

The evidence explicitly establishes #2, by saying it was impossible to meet the friend on time.

The evidence fails to establish #1, that the promise-maker ought to have met their friend on time.

If you negate (D), the correct answer, it weakens the argument by saying that "there's no obligation [no should] about that promise any more".

It takes the author even farther from having established #1.

Did you mean to ask about (C) or were you asking about the correct answer, (D)?
(C) is just doing an illegal negation of the rule cited in the first sentence. It's trying to feel appealing by sounding familiar, but when you compare it to the rule it sounds like, you can see that it's just doing a negation.

First sentence:
"If you ought to do it, then you can do it"

(C)
"If you ought not to do it, then you're incapable of doing it"

[HariI324]

I'm developing an exercise where I write out an explanation for every question I miss. Hope it helps others.

If anyone has comments/corrections please feel free.

The ethicist posits that the principle - that if one ought to do something one can do something - is false. In support, he cites an example, the example being a friend promising another to meet them at a certain time, but due to a traffic jam fails to do so.

The flaw is that only half of the ethicist's example is directly analogous to the principle in question. The traffic jam precluding the friend from meeting the other addresses whether someone can or cannot do something, however the first half of the example - the promise - does not clearly establish whether meeting the friend is something that the friend ought to do ("keeping promise" = "something one ought to do" is the missing link).

In the answer choices, we need to look for something that establishes that keeping a promise = something one ought to do.

A) This is a trap answer that actually switches the necessary and sufficient. We're looking for something that says if promise --> ought to do, not if ought to do --> promise
B) The ethicisit never cites exclusivity w/ respect to their example
C) This is simply taking the converse of the principle in question, and does not directly address the flaw in the ethicist's argument
D) In a roundabout and subtle way, this does suggest that keeping a promise = something that one ought to do. To litmus test, negating this assumption - the obligation created by a promise is relieved by the fact that the promise cannot be kept, actually says that keeping a promise is not necessarily something that one always ought to do; breaking that equivalency would break the ethicist's argument
E) Does not address the flaw in reasoning, also introduces a new assumption that the argument neither suggests nor is required to by the ethicist's argument.

[WesleyC316]

I still have questions about A. Isn't A the contrapositive of " if you promise to meet a friend, then you ought to do so", hence it addresses the first part of the general principle?

I'm having the same confusion. Can someone help us out here? Thanks!

[DPCTE4325]

I still have questions about A. Isn't A the contrapositive of " if you promise to meet a friend, then you ought to do so", hence it addresses the first part of the general principle?

I'm having the same confusion. Can someone help us out here? Thanks!

Could an instructor respond to this please? Isn't A the contrapositive of what we're looking for ( P --> O?)

Or is A wrong because "failing to do something that one ought to have done" is NOT the same as "/ought"? B/c the sufficient part of A could be interpreted as "one made the obligation, just failed to deliver on the specifics." And the premise only talks about "ought to do something", meaning making the initial obligation itself.

Thoughts?

[RobinC369]

I still have questions about A. Isn't A the contrapositive of " if you promise to meet a friend, then you ought to do so", hence it addresses the first part of the general principle?

I'm having the same confusion. Can someone help us out here? Thanks!

Could an instructor respond to this please? Isn't A the contrapositive of what we're looking for ( P --> O?)

Or is A wrong because "failing to do something that one ought to have done" is NOT the same as "/ought"? B/c the sufficient part of A could be interpreted as "one made the obligation, just failed to deliver on the specifics." And the premise only talks about "ought to do something", meaning making the initial obligation itself.

Thoughts?

I have the same question about this and how you should approach thinking about answer choice A. I also thought that failed to do something ought to have done was the same thing as ~ought to do something.

[EmilyL849]

Hi,

I had the same trouble with (A). Because the negation seemed to destroy the conclusion.
I think I figured out why (A) is not necessary. So let me try to throw in my two cents... and I would appreciate if any of the instructors can confirm whether my reasoning is valid.

The conclusion is saying that it is possible that "even if one ought to have done something, one could not do it".
In order to support this the author gives one example where one promised to do something, but one could not deliver that promise.
So, it is established that in this case, one could not meet a friend. What we need is connection between a promise to meet a friend and an obligation to do so.

The reason why (A) is not necessary is because we do not need all promises to be obligations. We just need ONLY IN THIS CASE, a promise means an obligation. All author is trying to prove is that there is AT LEAST one case where a promise --> an obligation.

If you negate (A) "Even if one failed to do something one ought to have done, one DID NOT failed to do something one promised to do." So, there is at least one case one failed to keep an obligation yet one succeeded in delivering a promise. The author would say, "yeah, that could be true. But all I am trying to say is that in my example, a promise means an obligation."

Is this a right way of getting rid of (A)?

Thank you!

[ohthatpatrick]

Yeah, nice job.

I can see why everyone is getting struggling with (A).

We know the author is assuming
"if you promised to do X, then you ought to do X"

The contrapositive would be
"If X isn't something you ought to have done, then X isn't something you promised to do"

(A), meanwhile, says
"If you ought to have done X but failed, then you promised to do X but failed."
(This is moving from "if it's something you ought to have done, then it's something you promised to do", which is the illegal reversal of the assumption we're looking for)

Remember, the correct contrapositive of the author's thinking was
"If X was not an action you ought to have done ....
and (A) is saying
"If X was an action you ought to have done but failed to do ...

Hopefully that illustrates the difference between
~Ought -->
and
Failed to do Ought -->

(A) would have the same conditional logic meaning if we replaced the verb 'failed' with any other verb.

- If a person decided to do something they ought to have done, then they decided to do something they promised to do. (ought --> promised)

- If a person tiptoed around doing something they ought to have done, then they tiptoed around doing something they promised to do. (ought --> promised)

- If a person reconsidered something they ought to have done, then they reconsidered something they promised to do. (reconsidered --> promised)

Because we're repeating the verb in each half, it has no logical bearing on the statement.
"If you ran over an X, then you ran over a Y."
The trigger already says you ran over something, so the consequence is just repeating the same verb. The logical move is going from X with certainty to Y.

Finally, if you want to eliminate (A) as a conversational human might, remember that the author's assumption is actually a pretty plausible idea people would hold in the real world:
"If you promised to do X, then you ought to have done X"

Meanwhile, (A) is an extreme, perverse idea that no one in the real world would hold:
"If you failed to brush your teeth [which is something you ought to have done], then you failed to do something you promised to do [you promised to brush your teeth?]"

"If you failed to get an oil change last year [which is something you ought to have done], then you failed to do something you promised to do [you promised to get an oil change last year?]"

Hope this helps.