#11 - If the forest continues to disappear at its present

[Dave Killoran]

Question Explanation

Must Be True. The correct answer choice is (B).


One of the reasons I love this question is because the question stem references the idea of "consistency." The word consistent is one that means something a bit different on the LSAT than it tends to be used in real life.

In real life, most people use consistent to mean agreement. Thus, these two statements would be inconsistent to most people:

• Statement 1: All flowers are yellow.
  
  Statement 2: My house is purple

In real life, typically people want to see an agreement between two statements to call them consistent. If they don't directly agree, then most people say they are inconsistent.

The LSAT works differently, and uses the logical definition of consistency. The logical definition of consistent is that it means "could be true," and that inconsistent means "cannot be true." Thus, the two statements above would be considered consistent on the LSAT.

Most of the time this difference isn't an issue because consistency rarely appears on the test, but it becomes one when a question uses that concept, as is the case here.

So, what are the operational effects of the LSAT meaning of consistent? Well, the first thing to consider is that millions of statements are consistent. Just about any two statements will be consistent, as long as they don't contradict each other. Inconsistent statements must contradict each other. Thus, when this particular question stem asks for what is consistent with one statement but inconsistent with another, you shouldn't worry about finding the consistent part because most of what you see will be consistent. Instead, search directly for the answer that is inconsistent, because it will have a very specific characteristic of contradicting the politician's statement.

In this case, the politician said:

D SK.

The answer we need has to contradict that, which would be:

D SK.

That's precisely what (B) says (and, as noted already, that answer is consistent with what the biologist said).

Regarding the diagramming of the Politician's statement, the phrase "all that is needed" is a tricky one. It includes a sufficient term, "all", as well as a necessary term, "needed." But if you take a step back and think about what that phrase really means, it really equates to "enough" or "sufficient. The other trick is that phrase is modifying "stop deforestation" NOT "save the koala." So here:

"All that is needed to save the koala is to stop deforestation"

is like saying:

"Stopping deforestation is sufficient to save the koala."

So that rule would be diagrammed:

Stop deforestation Save Koala

Answer choice (D) would be consistent with both of their statements. Neither one of them really speaks to what happens if deforestation is slowed. The biologist only speaks of what happens deforestation continues at its present pace. The politician only speaks about what happens if deforestation is stopped. Slowing deforestation would show that it is not continuing at its present pace and also that it might be stopping. In either case, that would not be enough information to activate either one of these rules. And since neither of the rules necessarily applies to answer choice (D), then it does not violate (it is not inconsistent with) either one of them.

Put another way, in answer Choice (D), slow deforestation and the koala survives, is consistent with what the politician said, but we are looking for an answer that is INCONSISTENT with what he said. We want something that can be true in light of the biologist's claim, but cannot be true if the politician's claim is true. That's why B works - the politician is saying that if we stop deforestation, the koala will survive, and B contradicts that, while D does not.

[RayMiller]

This question is about koala's and deforestation. I attempted but selected the incorrect answer and came back to it, but still can't seem to understand why B.

[Nikki Siclunov]

Hi Ray,

Can you tell us a bit more about how you approached this question and which answer you selected? It would be helpful to know your train of thought here.. it's a confusing question for sure. Keep in mind that the phrase "consistent with" - in LSAT jargon - means the same as "could be true." In other words, your goal is to select a statement that could be true given the biologist's claim, but cannot be true in the context of the politician's claim.

Thanks!

[RayMiller]

Yes :/

Biologist- Current Deforestion Slowed Koala
or Deforestation no Koala

I really wasn't positive. Especially once I got to the answer choices.

Politician - Koala no Deforestation

I selected .D

[Steve Stein]

The biologist says that if deforestation continues, the koala will approach extinction:

deforestation continues koala approaches extinction
Koala NOT nearing extinction NO deforestation

The politician thinks that stopping deforestation is sufficient (that is, all that is needed) to save the koala:

NO deforestation Koala saved

The question asks for the answer choice that has no inconsistency with the biologist claim, but is inconsistent with the politician's claim. Answer choice B provides a scenario (NO deforestation, Koala NOT saved) that is inconsistent with the politician's claim--according to the politician, if deforestation was stopped, the koala should have been saved.

The biologist's claim is not inconsistent with this scenario, because according to the biologist, "NO deforestation" is not sufficient to arrive at any conclusion.

I hope that's helpful! Let me know whether it's clear--thanks!

~Steve

[RayMiller]

I understand with your explanation but when I was diagrammed I was confused by ”needed” in the politician's statement. I understand in conditional reasoning that need is a indicator of what's necessary but I then I reread it to mean the deforestation needs to end in order to save koalas.

Ugh...how do I get out of doing this? Do I just stick treating these sentences like a puzzle? Meaning, what follows suf indicator is sufficient, what follows necessary indicator is necessary. And apply without, unless, until, except rule when appropriate?

[Steve Stein]

Relying on indicators is often effective--otherwise, you can either rephrase the statement or reason your way through it.

The politician claims that putting a stop to deforestation is all that is needed to save the koala--in other words, putting a stop to deforestation is sufficient to save the koala. When the author says "this is all that has to be done" to achieve something, that means it is sufficient to achieve that thing.

I hope that's helpful! Let me know--thanks!

~Steve

[RayMiller]

Yes definitely understood. Now, let's see how it goes in application.

Thank you so much

[r miller]

there were a lot of great, helpful answers given to ray for this classic, somewhat difficult question. steve followed up nikki by giving you some diagramming help. i'd like to go back and further emphasize nikki's answer.

of course, the problem is the way in which the question stem is formulated.

getting away a bit from the straight or formulaic formal logic, it is often helpful to support that with some intuitive understanding - what we sometimes call abstract reasoning. think about what's being said by each speaker in the context of what various answer choices mean. specifically, it's helpful to realize that you are looking for something that is CONSISTENT with what a speaker said. it needn't be absolutely true or follow exactly, or, as nikki said, you are asked for what could be true. i like to say it would follow logically, although we want to stay away from the suggestion here of a causal idea. it would follow logically from what the speaker is saying.....

hope that also helps.

good luck!

[GLMDYP]

Hi Powerscore!
Just wondering how does (B) fit into the description that "consistent with the biologist's claim but not with the politician's claim".
Thanks!