Seeing inconsistency with PT 30-2-21 and PT 55-3-14

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timmydoeslsat

Posts: 148
Joined: Wed Aug 03, 2011 2:07 pm

Seeing inconsistency with PT 30-2-21 and PT 55-3-14

I ran across a question today that appeared to be testing the same concept as a previous test. The two items in question are from PT 30-2-21 and PT 55-3-14.

PT 30-2-21

Premise: Leaders of all major parties oppose bill

Conclusion: Bill will almost surely fail to pass.

Strengthen question.

The two most attractive answers here were A and B.

A) Bills that have not been supported by even one leader of a major party MOST ~passed into law

B) Bills that have not been passed into law MOST ~supported by even one member.

(I realize that there is a shift of language in this answer choice from leader to just member, but for the sake of argument, even if this answer choice would have used the word leader, the logic behind this answer choice is still not right)

To have this conclusion state a probability associated with it based on characteristics of this bill, we need to know something about the characteristics of this bill. For all we know, perhaps even bills that are passed are not supported by even one leader of a major party.

So that is why A is correct.

However, in PT 55-3-14. The correct answer essentially is "B" from above. While this answer choice does not give us an "A" like the one above.

This seems inconsistent. Why would an answer choice not be given in terms of likelihood based on the characteristics we know from this building.

chewdak

Posts: 106
Joined: Fri Apr 03, 2009 5:54 pm

Re: Seeing inconsistency with PT 30-2-21 and PT 55-3-14

you lose me with
timmydoeslsat wrote:....To have this conclusion state a probability associated with it based on characteristics of this bill, we need to know something about the characteristics of this bill. .... Why would an answer choice not be given in terms of likelihood based on the characteristics

I hope my perspective is simpler without being wrong:

agriculture bill:
premise: all major party leaders oppose the bill
conclusion: bill will most likely fail

to be logical the conclusion must follow from the premise:
if all major party leaders oppose the bill, then the bill will most likely fail

(a) "if not one of the major party leaders support the bill, then the bill will most likely fail"
gives you that and more: 'all oppose' is a subset of 'not one supports'

ancient building:
premise: structure uses non-local building materials
conclusion: this structure is probably not a human dwelling

again, to be logical, we need "if structure uses non-local building materials, then it probably is not a human dwelling"
This is similar to (b) 'most buildings which are not human dwellings used non-local building materials'

timmydoeslsat

Posts: 148
Joined: Wed Aug 03, 2011 2:07 pm

Re: Seeing inconsistency with PT 30-2-21 and PT 55-3-14

chewdak wrote:
ancient building:
premise: structure uses non-local building materials
conclusion: this structure is probably not a human dwelling

again, to be logical, we need "if structure uses non-local building materials, then it probably is not a human dwelling"
This is similar to (b) 'most buildings which are not human dwellings used non-local building materials'

I disagree on this part.

I would think that we would want:

"Most non-local building material buildings are not human dwellings."

That would tell us that it is probably the case that the building in question is not a human dwelling.

This answer choice of B is simply telling us a a characteristic of not human dwellings.

This answer choice of B matches the INCORRECT answer from PT 30:

"Most bills that fail to pass are not supported by even one major party leader."

This is not a correct answer choice because we cannot determine the probability of the bill in question.

So, since this is the case, these two questions must have some sort of difference inherent in them that I am not seeing at the moment. I realize that PT 30's question is simply 1 premise and a conclusion and we are looking for a link to connect the two, but this problem from PT 55 does not appear to be different.

chewdak

Posts: 106
Joined: Fri Apr 03, 2009 5:54 pm

Re: Seeing inconsistency with PT 30-2-21 and PT 55-3-14

timmydoeslsat wrote:
chewdak wrote:
ancient building:
premise: structure uses non-local building materials
conclusion: this structure is probably not a human dwelling

again, to be logical, we need "if structure uses non-local building materials, then it probably is not a human dwelling"
This is similar to (b) 'most buildings which are not human dwellings used non-local building materials'

I disagree on this part.

I would think that we would want:

"Most non-local building material buildings are not human dwellings."

That would tell us that it is probably the case that the building in question is not a human dwelling.

This answer choice of B is simply telling us a a characteristic of not human dwellings.

This answer choice of B matches the INCORRECT answer from PT 30:

"Most bills that fail to pass are not supported by even one major party leader."

This is not a correct answer choice because we cannot determine the probability of the bill in question.

So, since this is the case, these two questions must have some sort of difference inherent in them that I am not seeing at the moment. I realize that PT 30's question is simply 1 premise and a conclusion and we are looking for a link to connect the two, but this problem from PT 55 does not appear to be different.

Could you clarify the difference between 'most buildings which are not human dwellings used non-local building materials'
and "Most non-local building material buildings are not human dwellings." ?

also, where do you get "Most bills that fail to pass are not supported by even one major party leader." ? The answer choice (b) uses 'even one major party member'. Using 'member' rather than 'leader' is outside the scope of the original argument and makes this choice wrong.

timmydoeslsat

Posts: 148
Joined: Wed Aug 03, 2011 2:07 pm

Re: Seeing inconsistency with PT 30-2-21 and PT 55-3-14

I previously stated in my first post that I would like to discuss that answer choice B with the idea of member being replaced with party leader. I feel that even if that switch was made, that answer choice B would still be incorrect because of the quantifying logic behind the stimulus.

Here is the point of my post, and I thank you for posting a reply:

My example problem:

~Supported
_________________
Probably ~Pass

Which one strengthens the argument?

A) ~Supported MOST ~Pass

B) ~Pass MOST ~Supported

This is the heart of my question. Do you not see how B would not strengthen our conclusion and that A would.

There is, obviously, a difference between the two answer choices. We know something about ~Supported in that example problem, it is a premise. We, however, do not know the likelihood of it not passing.

Answer choice A takes this premise and gives us a likelihood.

My point is, why isn't this the answer on PT 55-3-14:

B) Most non-local building material buildings are not human dwellings

This would indeed strengthen the argument. However, we are given information about the not human dwellings. This is similar to us being given information about the ~pass, which was not the right answer in PT 30.

Why isn't this used as the answer by the LSAC for PT 55?

B) Most non-local building material buildings are not human dwellings

chewdak

Posts: 106
Joined: Fri Apr 03, 2009 5:54 pm

Re: Seeing inconsistency with PT 30-2-21 and PT 55-3-14

timmydoeslsat

Posts: 148
Joined: Wed Aug 03, 2011 2:07 pm

Re: Seeing inconsistency with PT 30-2-21 and PT 55-3-14

That is not very appropriate in my opinion.

I would like to know why the reverse of b was not used, as it was in that form on PT 30.

To say that b is right because it is right is not helpful.

yoni45

Posts: 72
Joined: Fri Feb 02, 2007 2:12 am

Re: Seeing inconsistency with PT 30-2-21 and PT 55-3-14

Okay, here goes... ^_^

In both cases, knowing that most of the "other" side meets that criteria does strengthen the argument, it just doesn't do it nearly as much as the direct statement you were looking for.

It's easier to see if you take extreme alternatives. For example, let's take the laws passing or not passing:

You're right in that in order for the argument to fully hold, you need to assume that most of the ones without support happened to not pass. But let's take some random numbers:

50% of the laws passed, 50% of the laws didn't pass.

If we take the statement that most of the laws that didn't pass didn't have support, that means that at least 26%* of the total laws didn't have support, all of those in the "not pass" camp.

And of course, the issue here remains that: we don't know what proportion of the ones that *did* pass take up. I mean, it could be true that ALL of those that passed also had no support. In which case we now have at least 76% of the laws being unsupported, only 26% of which weren't passed. At this point, it's more likely that the law *did* pass. The chances of the law being in the "not passed" side are about 1/3 now.

But here's the thing, maintaining that number on the "passed laws" side, what if *fewer* than most of the laws not passed happened to have no support? What if, say, 0% of the laws that did not pass have no support? If this were to happen, the argument would fall apart: 100% of the cases of the laws not passing would now be on the "passed" side. Regardless of the initial numbers used, the lower that proportion of unsupported cases on the not-passed side gets, the weaker the argument becomes until it just becomes worthless (at 0%). The higher the proportion, the stronger it becomes (even though it might be enough to make it a good argument).

The same reasoning would apply to the dwellings argument.

And the thing is, the question type allows for this in both: since you're only looking to strengthen and not necessarily make valid, then the answer choices do meet the criteria.

For the argument with the laws however, answer choice (A) wins out because it objectively does more to strengthen the argument since it gives you the directly relevant data -- it guarantees that it is at least more than 50% likely to fail.

Hope this helps! =)

timmydoeslsat

Posts: 148
Joined: Wed Aug 03, 2011 2:07 pm

Re: Seeing inconsistency with PT 30-2-21 and PT 55-3-14

Thank you for the reply. I have been thinking similar things as a way to resolve this "inconsistency." And it is a matter of one answer strengthening more than another did.