Discussion
Which one of the following statements, if true and added to those above, most supports the conclusion that no ski resort owners are lawyers?
*This question is included in NP: Practice Set 2 - Conditionals, question #3
| (A) | Some cattle ranchers are lawyers. |
| (B) | ... |
| (C) | ... |
| (D) | ... |
| (E) | ... |
| (F) | ... |
The solution is
Posted: 07/18/2011 06:32
I don't understand why to arrive at "some lawyers are cattle ranchers" one needs to assume that "all lawyers are cattle ranchers" this doesn't seem logical.
Posted: 07/18/2011 09:27
Yeah, this one is nasty. First of all, you've got the argument's conclusion stated in the question stem, which makes it difficult to keep track of everything. And then there's the fact that you've got the "some"/"all" issue to deal with.
This is one of those passages you'll almost certainly have to diagram. So let's do that:
Premise 1: CR --> ~like W
Premise 2: SRO --> like W
Premise 3: "Some" (L + CR)
NP: ???
Conclusion: ~(SRO + L)
So, we have to justify the conclusion that no SRO's are also L's. How can we do that?
Well, what do we know about SRO's? We know that they *ALL* like "long winters". And we know *NO* CR's like "long winters".
So you cannot be both an SRO and a CR. This is key.
So now we're trying to prove that no L is an SRO. How do we do that?
By making every L a CR.
This give us:
P1,NP: L --> CR --> ~like W
P2: SRO --> like W
Conclusion: ~(SRO + L)
This question is confusing because the correct answer choice seems to be nothing more than premise 3 restated in slightly stronger form. And actually, it IS a stronger form of premise 3. But that's what is required to draw the conclusion "No ski resort owners are lawyers". Premise 3 is essentially a diversion. (Note, however, that premise 3 and the Necessary Premise DO coincide. You'll never have a Necessary Premise that conflicts with a premise in the argument.)
If this is making your head spin, relax. These get a lot easier with practice.
This is one of those passages you'll almost certainly have to diagram. So let's do that:
Premise 1: CR --> ~like W
Premise 2: SRO --> like W
Premise 3: "Some" (L + CR)
NP: ???
Conclusion: ~(SRO + L)
So, we have to justify the conclusion that no SRO's are also L's. How can we do that?
Well, what do we know about SRO's? We know that they *ALL* like "long winters". And we know *NO* CR's like "long winters".
So you cannot be both an SRO and a CR. This is key.
So now we're trying to prove that no L is an SRO. How do we do that?
By making every L a CR.
This give us:
P1,NP: L --> CR --> ~like W
P2: SRO --> like W
Conclusion: ~(SRO + L)
This question is confusing because the correct answer choice seems to be nothing more than premise 3 restated in slightly stronger form. And actually, it IS a stronger form of premise 3. But that's what is required to draw the conclusion "No ski resort owners are lawyers". Premise 3 is essentially a diversion. (Note, however, that premise 3 and the Necessary Premise DO coincide. You'll never have a Necessary Premise that conflicts with a premise in the argument.)
If this is making your head spin, relax. These get a lot easier with practice.
Posted: 07/18/2011 10:44
I get it now and it was my own mistake for not adding the conclusion to the stimulus which made me ignore it when looking at the answer choices. Thank you for clarifying.