#14 - Ethicist: The general principle—if one ought to do

[Administrator]

Please post below with any questions!

[lsatstudent]

Hello!

This is one of the LR questions I got wrong on the test. I originally answered A.

My thought process:

The question doesn't seem to have a gap in logic so this must be a defender assumption.
A
B would weaken the argument
C not relevant to this argument
D
E doesn't seem to be necessary for the argument to be true.

I don't fully understand why A is incorrect. Is A a shell game? Why is D correct?

Thank you,

Confused LSAT student

[Nikki Siclunov]

Hi lsatstudent,

Thanks for your question. The author considers the following principle: if you ought to do something, then you can do it. In conditional terms, the principle can be diagrammed as follows:

• Ought to do Can do

The principle is rejected as being inconsistent with a purported counterexample, whereby you can't keep a promise you've made (for reasons beyond your control). The counterargument is not iron-clad, as there is no evidence that you necessarily ought to do the things you promise to do. Are promises necessarily obligations? And if they are, are there any circumstances in which they can be relieved? This line of reasoning brings us to answer choice (D). To test if (D) is an assumption, use the Assumption Negation Technique and examine if the logical opposite of that answer weakens the conclusion of the argument:

• Logical Opposite of (D): The obligation created by a promise is relieved by the fact that the promise cannot be kept.

Clearly, if the impossibility of keeping the promise relieves the obligation created by it, then the counterexample does not really refute the original principle. After all, if you no longer ought to do the thing you promise to do, the principle in question wouldn't even be triggered in the first place: the principle concerns actions you are obliged to do ("if one ought to do something...'), not actions you are off the hook for.

I realize you're considering answer choice (A) as a contender, and I can see why: it attempts to connect the two central elements in this argument. However, it's indeed a Shell Game. In the counterexample given, our friend failed to keep a promise, which is not tantamount to failing to do something she ought to have done. In other words, we haven't established that anyone has failed to do something they ought to have done, because a promise is not necessarily an obligation. If you're still considering answer choice (A), try the Assumption Negation Technique:

• A person can fail to do something they ought to have done without necessarily failing to do something they promised to do.

Given that we haven't established whether the person in question ought to have met the friend at a certain time (they only promised to meet him), the implications of the logical opposite are moot.

Hope this clears it up! Let me know if you have any other questions.

Thanks,

[ChicaRosa]

I also choose A for this one too! Is it wrong because it's a mistaken negation of the principle in the stimulus?

Thanks!

[Adam Tyson]

Not exactly, ChicaRosa. The MR of that principle would be "if you can do it then you ought to do it." Answer A brings up something else - the "promise" concept. There is another assumption in this argument, although it ends up not being the one we are looking for, and that is that you ought to do the things you promise to do. Conditionally, that would be:

P(romise) O(ught to do it)

A good contrapositive would be:

O P

Answer A somewhat misstates that contrapositive by twisting into being about failing to do something, rather than that thing not being something you ought to do. In a sense, it's also a Mistaken Reversal of the original claim above (which, remember, was not in our stimulus, but is another assumption built into the stimulus). The answer is based on the belief that anything you ought to do must necessarily be something you promised to do.

I promise that I was trying to help clear things up, and I know I ought to be doing that, so I hope I didn't fail!

[tayloramalkin]

Does the phrase "does not always hold true" have any impact on the conditional statement? Wouldn't that be the authors conclusion and the example would be its support?

[Adam Tyson]

You got it, Taylor! The claim that the original conditional claim "does not always hold true" is another way of denying the absoluteness of the conditional claim. In other words, the necessary condition really isn't necessary. There can be things you ought to do that you cannot do.

The example is supposed to show that - something that you ought to do (because you promised) that you nevertheless cannot do. That's the premise supporting the conclusion that the conditional claim is not always correct.

The assumption is that you still ought to do what you promised, and that the inability to do it doesn't cancel out the "ought".

Nice work!

[Etsevdos]

You got it, Taylor! The claim that the original conditional claim "does not always hold true" is another way of denying the absoluteness of the conditional claim. In other words, the necessary condition really isn't necessary. There can be things you ought to do that you cannot do.

The example is supposed to show that - something that you ought to do (because you promised) that you nevertheless cannot do. That's the premise supporting the conclusion that the conditional claim is not always correct.

The assumption is that you still ought to do what you promised, and that the inability to do it doesn't cancel out the "ought".

Nice work!

'

I have seen question prompts like this in a couple instances: how would you diagram conclusion:

Out to do something--> you can do it

Arg the says this does not hold true: should we always negate necessary (not sufficient). Therefore, I believe (as you mention above), the authors actual conclusion would be written as : ought to do something-->you cannot necessarily do. The premise is essentially: Promise--> cannot necessarily do it.

Now, answer D: connects gap in jump from ought to do something in conclusion as sufficient to promise--> cannot necessarily do. Negating D: Promise--> you should do, makes the authors argument fall apart.

How would you diagram and negate A though?

[Adam Tyson]

Good analysis, etsevdos, although don't be afraid to be a little less mechanical and a little more holistic in your approach. While conditional diagramming is a useful tool, it is one that is often overused by students who could have gotten there easier and more naturally from a more commonsense approach.

My approach to answer A would be more holistic than diagrammatic. I read it as "if you failed, then you promised" (which leaves out the "oughts" but still captures the essential nature of the claim). My negation would be "failing doesn't mean you promised" or "I can fail at something even if I didn't promise to do it".

Mechanically/diagrammatically, I would probably tackle A this way:

FSOD (Fail at Something you Ought to DO) PD (Promised to Do it)

The negation of a conditional statement is not simply negating the necessary condition - it's showing that the conditional relationship is, in fact, untrue. So from a purely diagrammatic approach, I would simply take the entire diagram above and cross it out. That, to me, would mean "this is not a true claim". I would NOT negate the necessary condition, like this:

FSOD PD

Because that means failing proves that you did NOT promise, and that is not the same as saying that failing does NOT prove that you promised. It's too strong, and is the polar opposite when what we want is the logical opposite.

Be more holistic in your approach, and when dealing with conditionals you can negate them by simply saying that the sufficient condition is not, in fact, sufficient to prove the necessary condition. In other words, the sufficient condition can happen EVEN IF the necessary condition does not. The necessary isn't necessary, the sufficient isn't sufficient, the whole thing just isn't true.

I hope that helps. Keep up the good work!

[meercat44]

I'm having trouble wrapping my head around this one.

Looking at this -

Logical Opposite of (D): The obligation created by a promise is relieved by the fact that the promise cannot be kept.


Wouldn't this then help the Ethicist's argument? Proving that the principle "does not always hold true?"