http://7sage.com/lsat_explanations/lsat-61-section-2-question-23/So in JY's explanation the stimulus represents invalid argument form 4. But I'm having trouble seeing this. Had the second sentence read "most BRICK houses on river street with front yards also have two stories" it would have been a lot clearer to me. But it just says "most of the houses on river street that have front yards also have two stories" So presumably there could be 100 wooden houses on river street with front yards and only 5 brick houses. The 5 brick houses could have front yards but not two stories while the 100 wooden houses all have two stories. So I'm not sure how we are justified in claiming most brick houses with front yards have two stories. Very confused on this.
Comments
Stimulus:
BHR (Brick houses on river street)
F (front yard)
HRF (Houses on river street that have front yards)
2 (have two stories)
Premise: BRH --> F
Premise: HRF ---most--> 2
therefore: BRH -most-> 2
JY says this is invalid argument form number 4 but I don't see how we are justified in connecting F --> HRF
My objection is that BRH and HRF are not the same. No BRH having front yards is consistent with most HRF having front yards.
Correct Answer choice:
L (legislators)
not R (have not run for office)
P (public servant)
Premise: L ---> P
Premise: P --most--> not R
Therefore: L --most--> not R
To me this is very clearly argument form number 4 (A-->B--most--> C therefore A ---most--> C)
BH —> FY
FY -most-> TS
BH -most-> TS
Form in generic terms:
A —> B
B -most-> C
A -most-> C
AC D [rearranged to match stimulus]:
L —> PS
PS -most-> NRO
L -most-> NRO
I think it's most helpful with the "never run for office" condition in the answer choices to think of them as a characteristic as opposed to a negation of "run for office" (meaning, NRO = C in the generic form).
"No BRH having front yards" makes me wonder if you are thinking of this as a negation?
BRH is not the same as houses in general, they are a subset. This is also true in D where all legislators aren't the same as public servants in general, they are one body of people who are public servants (where are the judges, social workers, etc).