LSAT and Law School Admissions Forum

Get expert LSAT preparation and law school admissions advice from PowerScore Test Preparation.

 Administrator
PowerScore Staff
  • PowerScore Staff
  • Posts: 8924
  • Joined: Feb 02, 2011
|
#84616
Complete Question Explanation

Flaw in the Reasoning - Formal Logic. The correct answer choice is (D).

Answer choice (A):

Answer choice (B):

Answer choice (C):

Answer choice (D): This is the correct answer choice.

Answer choice (E):

This explanation is still in progress. Please post any questions below!
 stephee490
  • Posts: 5
  • Joined: Oct 24, 2020
|
#88482
Hello,

I got the answer choice correct, however, I didn't really understand the answer choice very well.

I mainly looked at Terry's argument noting down:

bad actions <some> favorable consequences

good actions -> favorable consequences

bad actions <some> good actions

However when it came to the answer choice D, I was confused due to the some arrow, are we supposed to consider the fact that arrow is reversible and that favorable consequences can become the sufficient condition and therefore bad actions the necessary condition in order to draw out the answer choice D?
So it would be

favorable consequences<some> bad actions

good actions -> favorable consequences

bad actions <some> good actions


Hence the necessary condition of favorable consequences becomes the sufficient condition for good actions, as what I believe answer choice D is stating?
 stephee490
  • Posts: 5
  • Joined: Oct 24, 2020
|
#88483
stephee490 wrote: Sun Jul 04, 2021 2:12 am Hello,

I got the answer choice correct, however, I didn't really understand the answer choice very well.

I mainly looked at Terry's argument noting down:

bad actions <some> favorable consequences

good actions -> favorable consequences




bad actions <some> good actions

However when it came to the answer choice D, I was confused due to the some arrow, are we supposed to consider the fact that arrow is reversible and that favorable consequences can become the sufficient condition and therefore bad actions the necessary condition in order to draw out the answer choice D?
So it would be

favorable consequences<some> bad actions

good actions -> favorable consequences

bad actions <some> good actions


Hence the necessary condition of favorable consequences becomes the sufficient condition for good actions, as what I believe answer choice D is stating?

I also want to ask, since it is an error in reasoning/flawed question type, due to the reversible relationship of the some arrow isn't Terrys argument valid? With formal logic rules then we could get...

good actions ->favorable consequences <some> bad actions

good actions <some> bad actions; bad actions <some> good actions

...therefore, I wonder is it really an error in reasoning or method of reasoning?

Please correct me where I am wrong, thank you.
User avatar
 Bob O'Halloran
PowerScore Staff
  • PowerScore Staff
  • Posts: 61
  • Joined: Jul 06, 2021
|
#88540
Hi Stephee,

Thank you for your question.

The flaw is Terry's argument is one of mistaken reversal. As you note:

Good actions ---->Favorable consequences

However Terry's conclusion is:

Favorable consequences ----> Good actions.

Just because an action has favorable consequences doesn't mean it automatically is good. There may be other unstated conditions which haven't been met.

Please let us know if this helps in understanding the flaw.
Bob
 stephee490
  • Posts: 5
  • Joined: Oct 24, 2020
|
#88579
Hello,

It does help, I did overthink it, but I am curious I assumed some reversible ( :some: ) applied. It feels more like a logic game question in this sense, so how should I distinguish between the two?
 Rachael Wilkenfeld
PowerScore Staff
  • PowerScore Staff
  • Posts: 1358
  • Joined: Dec 15, 2011
|
#88595
Hi Stephee,

The key is that the good :arrow: favorable consequences is not a "some," and is not reversible. That's the issue with trying to go from favorable consequences :arrow: good or favorable consequences :some: good. Since it's not reversible, we can't link things considered bad and good actions.

Hope that helps!
User avatar
 a.hopp
  • Posts: 15
  • Joined: May 15, 2023
|
#101876
I selected the correct answer, but the language of the answer choices was difficult for me to get through.

The "certain property" in the options refers to favorable consequences, correct?

It would be super helpful to get a breakdown of the answer choices in language that isn't so cumbersome :')

Thank you!
User avatar
 Jeff Wren
PowerScore Staff
  • PowerScore Staff
  • Posts: 374
  • Joined: Oct 19, 2022
|
#101896
Hi a.hopp,

The language in these answer choices certainly can be tricky at first, but by studying the language used by the test makers to describe the various flaws that appear on the LSAT and familiarizing yourself with the different ways that they describe these flaws, they become much easier to recognize and understand.

Before even looking at the answers, it's important to realize that both of these arguments contain an error in conditional reasoning that we refer to as a Mistaken Reversal, which basically means that the argument tries to go from a necessary condition to a sufficient condition, which is backwards. Of course, Mistaken Reversal is the term that we use, but the LSAT will describe this flaw in a number of ways, usually using the terms "sufficient" and/or "necessary" or synonyms for these terms, such as "confuses the necessary for the sufficient."

Here, Answer D is the only answer that uses these terms, and it correctly describes the Mistaken Reversals in the arguments above.

To answer your question, the "certain property" in Answer D refers to "favorable consequences" in Terry's argument, but refers to "not having favorable consequences" in Pat's argument.

The diagram for Terry's argument would be:

AG -> FC
(if an action is good, then it has favorable consequences)

Terry's argument then states that since some actions considered bad have FC (favorable consequences), some actions considered bad are AG (actually good).

Pat's argument uses the negative conditional statement "no"
The way that you diagram a negative conditional like "no, none, never," etc. is to negate the necessary.
Here, the diagram would be:

CB -> Not FC
(If an action is considered bad, then it does not have favorable consequences)

Pat's argument then states that since some good actions do not FC (do not have have favorable consequences), then some good actions CB (are considered bad).

As for the other answer choices,

Answer A is basically saying that if one property (like having favorable consequences) distinguishes two types of action, then there are many properties that distinguish them.

Answer B is basically saying that if most actions of a certain type (like good actions) share a quality (like favorable consequences), then all good actions would share that quality.

Answer C is basically saying that if certain actions (like good actions) share a certain quality (like favorable consequences) in a given society (like ancient Rome) then they would share that quality in all societies.

Answer E is basically saying that if a certain property (like favorable consequences) is shared by two different types of actions (like good actions and bad actions), then that quality is what distinguishes good and bad actions from all other actions (like actions that are neutral).

None of these wrong answers remotely get at the conditional flaw in the arguments above, and are just there to distract and confuse test takers. Having a solid prephrase really helps identify the correct answer here.
User avatar
 Falan Walker
  • Posts: 1
  • Joined: Aug 06, 2023
|
#102688
Can someone double check my understanding of the question? I know the answer is D.

Here's my conditional logic diagram for Ted:

1) Bad actions <-some-> favorable consequences
2) Good action -> favorable consequences
3) Conclusion: Bad actions <-some-> good actions



I combined logic chains 1 and 2:

GA -> FC <-some-> BA

According to chapter 13 on formal logic, the all arrow ( -> ) can't be reversed. Meaning, I can say that some bad actions have favorable consequences, but I can't extrapolate that these particular bad actions are good actions because I can't "work up" the all arrow. Thus, Terry's conclusion (logic chain 3) is incorrect.

In order for Terry to make the conclusion that he does, favorable consequences would have to be the sufficient condition:

1) FC -> GA
2) BA <-some-> FC
3) Chained together: BA <-some-> FC -> GA
4) Conclusion: BA <-some-> GA (because you can move from left to right to make this conclusion)

In order to demonstrate mastery over this type of question (flaw in the reasoning- formal logic), should I expect to be able to identify mistaking the necessary for the sufficient without all this diagramming? If so, how can I teach myself to quickly do this?
 Rachael Wilkenfeld
PowerScore Staff
  • PowerScore Staff
  • Posts: 1358
  • Joined: Dec 15, 2011
|
#102776
Hi Falan,

Your drawing was right on! Good diagramming!

As to your larger question about how to do this in a timed environment, you should (hopefully) be able to see the issue with less diagramming than you ended up doing. Your initial diagram of Ted's error should be sufficient to see the problem. Answer choice (D) is the only one that describes that error in Ted's reasoning. You could have also drawn out Pat's error is essentially the same---you can draw it out if you'd like, but once you see that answer choice (D) is the only one to describe Ted's error, you don't have to go any further.

Part of the skill on this test is learning how much work you need to do upfront, and how much you can only do if required. Some of that comes down to your own skill level/comfort level with the task. For example, if you struggle to see a contrapositive up front, you should write it out with conditionals in MBT questions. That helps avoid an error they are very likely to test. Your goal with conditionals is to get to the stage where you can write them as you read them---that is, whenever you would see a phrase like "only if" or another indicator, you automatically look to see if it's conditional, and draw it out as you read. For me, I can write them out faster than I can decide if it's worthwhile to write them out. In a case like this, with multiple conditionals, I'd focus on one argument at a time, eliminate answer choices that don't fit that argument, and then draw out the second set of conditionals if needed to decide between the answer choices left. In this case, there's only answer choice (D) left, and thus I don't need to draw anything else.

Hope that helps!

Get the most out of your LSAT Prep Plus subscription.

Analyze and track your performance with our Testing and Analytics Package.