Q19 - Even in ancient times, specialized

[skapur777]

I narrowed it down to B and D, which makes sense. But I was wondering why D isn't correct? Does he not assume a causal relationship between specialized farms and urban populations?

Kind of confused here! I totally understand B though and why its correct. gah!!!

[sbuzzetto10]

I also narrowed it down to B and D!

My reasoning behind eliminating D was that the relationship between specialized farms and urban populations is not a causal one. If you read the blurb, it doesn't suggest that an urban population caused specialized farms or that specialized farms caused urban populations. It does indicate that an urban population was a necessary precondition "such markets presuppose urban populations" for the existence of specialized farms. The blurb then concludes that since the region could not have supported specialized farms, it must not have been an urban population. It gets the necessary/sufficient relationship confused.

Also, D says "because two things usually occur in conjunction with one another..." this is not what the blurb is saying.

Hope that helps!!

[ManhattanPrepLSAT1]

Perfectly explained.

Let me just run through the incorrect answers for those who might be wondering about other answer choices.

(A) contains a different error - this is "parts to whole." The stimulus is mistakes "sufficient for necessary."
(C) contains a different error - this is "equivocation."
(D) contains a different error - this is "correlation vs. causation."
(E) contains a different error - this is "circular reasoning."


Great explanation sbuzzetto10!

[mxl392]

I get tripped up by "such markets presuppose urban populations". Doesn't this mean that farmer markets are necessary for the cities? That would make the farms the necessary condition. I realize that in the first sentence, it says that cities are the necessary condition. It seems like the stimulus is saying:

"If farm -> must be city"
"Farms are necessary for cities, so If city -> farm"

That's what led me to pick D, which is a two-way kinda deal

[timmydoeslsat]

Think about the statement in this way:

The purchase of a large beach home presupposes one is rich.

LBH ---> R

So the argument looks like this:

SF ---> Large Markets ---> UP
~SF
______________________
Tell me what we can conclude!

Certainly nothing! But this argument believes that by taking away one possible way to reach "Large Markets" and "UP".....we have in fact made it impossible to reach those two terms.

Could it not be true that ~SF also leads to Large Markets and UP?

As Matt said above, answer choice D is describing a correlation-cause issue.

[WaltGrace1983]

I thought I'd dive into this argument a little bit more because it is a fun one. Here is what we got:

"Specialized farms...exists only where there were large commercial markets"

"Such markets presuppose urban populations"

Specialized Farms → Large Commercial Markets → Urban Populations
+
~Specialized Farms in Kadshim
→
~Urban Populations

Bam! Mistaken reversal! Just because there are no specialized farms does not mean that there is no urban population. A specialized farm is a sure fire way of having an urban population but that doesn't mean it's the only way. Something like a huge trading economy can also lead to urban populations! Therefore, it would be wrong to conclude that just because the "sufficient" condition didn't happen that the "necessary" condition didn't happen. In this case, the "Specialized Farms" is the "sufficient" and the Urban Population is the "necessary."

(B) says this perfectly. (B) talks about the nonexistence of evidence, aka, the nonexistence of the sufficient/premise to mean that the necessary condition didn't happen.

(D) is wrong because, as one already said, there is no causal relationship here. There is a difference between conditional and causal. Just because one thing happening means another thing happens doesn't mean that the one thing happening causes the another thing.

[VendelaG465]

I was reading on page 155 of the LR textbook and got tripped up in regards to the conditional logic indicators. Apparently there were a lot in this question. Looking back I was able to narrow in on "only" but what other conditional logic indicators are being mentioned in this question? I completely eleminated (B) assuming it wasn't a conditional logic flaw