#22- The folktale that claims that a rattlesnake’s age can

[180bound]

Hello, I am confused with this one. I understand how E would strengthen the argument because it is essentially outside information i.e. "the folktale is false BECAUSE rattlesnakes molt as often etc."....However, I am not seeing this as an assumption that the author necessarily committed too? To me the author's theory could stand on its own without without E. It seems to me that E is just more information that supports his claim not an assumption that he HAD to rely on. Can someone help me with this?

Thanks!

[Coleman]

I chose D instead of E because I thought the brittleness should be totally ruled out in determining the age of a rattlesnake.

D states "The brittleness of a rattlesnake's rattle is not correlated with the length of the rattlesnake's life."
If this brittleness is somehow correlated with the length of the life whether it gets more or less brittle as they get older or younger, then this brittleness could also be an indicator to figure out the age of the rattlesnake.

In other words, if we apply this into the denial test, it says "The brittleness of a rattlesnake's rattle IS CORRELATED with the length of the rattlesnake's life." Doesn't this destroy the conclusion, thus a necessary assumption that the argument depends on? For me, it sounds like the brittleness is another determinant in addition to how many times they molted in order to determine the age of the rattlesnake.

[Adam Tyson]

I don't see any impact of that negation on the conclusion of this argument, Coleman. The conclusion is that if the rattles were not that brittle, we could use them to calculate the age of the snake. Even if brittleness is correlated with age, we still might have an easier time if they were not so brittle, because then we could just count them and know the age of the snake.

Consider the prephrase here - the author has to believe that counting the number of rattles would be a reliable indication of age. That means he must believe that each molting, and thus each rattle, happens at some known, regular interval. Otherwise, how would knowing the number of rattles tell us anything about age? What if they molt whenever they feel happy, or whenever they are stressed, or whenever a new Marvel movie is released in theaters? We'd know how many rattles they had, and then we would know how often they had been happy, or stressed, or how many Marvel movies there were, but still no indication of the age of the snake.

I hope that clarifies the key issue here for you! It's not what the brittleness tells us, but what we WOULD be able to tell if the rattles were NOT brittle that matters.

[ashpine17]

I am still confused about answer choice C. If it were negated then wouldn't it state rattlesnakes molt just as frequently when they are young as when they are old...wouldn't that be compatible with the argument?

[ashpine17]

And if answer choice C had stated instead that young rattlesnakes molt just as often as older rattlesnakes, if this statement were negated, wouldn't it not necessarily destroy the argument because we could possibly still figure out the rattlesnake's age if we knew how often it shed when it is old and young.

[ashpine17]

I feel that we have to interpret C in a very specific way and add on a bunch of assumptions in order for it to even weaken. If we did know the rate at which the rattlesnake molts when young versus when it’s old, then we could probably tell the age of the snake by the number of sections in its rattle even if the rates differed…but if we didn’t, then it’s a free for all. Does that mean this is at best a crappy weakener and is likely irrelevant to the argument? By irrelevant, I mean no impact.

[lschlueter]

I see the argument about E being more narrow than A, but here's the thing: I explicitly negated E, because it didnt seem clear that an even frequency of molting would necessarily imply that there is an objective standard by which to measure age.

the key phrase is "as often as". This dosent say that rattlesnakes have the same frequency of molting across different rattlesnakes, it just says that there is an even ratio regardless of food scarcity. Thus, this could be true, and yet two different snakes would have different molting frequencies (although those frequencies would not vary by food scarcity) and there would be no way to establish age of an individual snake.

Why does this not nix E? Please help!

[Robert Carroll]

ash,

I am still confused about answer choice C. If it were negated then wouldn't it state rattlesnakes molt just as frequently when they are young as when they are old...wouldn't that be compatible with the argument?

I think I can clear up all your posts - this is an Assumption question, so we're negating answer choice (C) by the Assumption Negation technique to see whether it's an assumption necessary for the argument. Remember what the Assumption Negation technique says - the correct answer is the one that, if negated, would destroy the argument. So you negated answer choice (C)...and that negation was compatible with the argument. That decisively proves it's an incorrect answer. If it were correct, negating it should be harmful, not compatible.

I see the argument about E being more narrow than A, but here's the thing: I explicitly negated E, because it didnt seem clear that an even frequency of molting would necessarily imply that there is an objective standard by which to measure age.

the key phrase is "as often as". This dosent say that rattlesnakes have the same frequency of molting across different rattlesnakes, it just says that there is an even ratio regardless of food scarcity. Thus, this could be true, and yet two different snakes would have different molting frequencies (although those frequencies would not vary by food scarcity) and there would be no way to establish age of an individual snake.

Why does this not nix E? Please help!

lschlueter,

I think you're saying that answer choice (E) doesn't prove the conclusion. This isn't a Justify question, so that's not at all an objection to the answer choice. This is an Assumption question. The issue is not whether answer choice (E) proves the conclusion, but whether the argument can survive if answer choice (E) is false. So: if rattlesnake molting differs in rate based on food scarcity, then the molting is too irregular for us to tell a rattlesnake's age by its rattle. The negation of answer choice (E) destroys the argument. So answer choice (E) is correct.

Robert Carroll

[German.Steel]

(E) raises a question about commonsense on the LSAT. So I dismissed (E) because the negation of (E) doesn't wreck the argument, as far as I can tell, due to the possibility that rattlesnakes could have a steady food supply that does not vary. If that were the case, (E) would not be a necessary assumption.

However, I'm assuming the LSAT folks would rebut this claim by saying it's commonsense that food supply for an animal will not be steady in all cases. Am I correct?

Also, am I correct in saying that this is a feature of old tests more so than new? I can't recall any NA questions from tests 70-90 that would require you to make some "commonsense leap" like this to see why a answer is correct/why a negation would destroy an argument.

Thanks in advance!!!

[Robert Carroll]

German,

You're missing the "reliably" part of the stimulus. We have no idea whether rattlesnakes are going to have steady food supplies. The author thinks that, if rattles were not so brittle, that would be enough for us to reliably infer a rattlesnake's age from the number of sections of its rattle. If the negation of answer choice (E) were true, then differences in plentitude of food could result in different intervals of molting. So the idea of looking at the number of sections of a rattle and determining how old a rattlesnake is would be unreliable, because it would depend on factors that would not "show up" in the rattle. The "information" about how plentiful food is would be lost - we see two rattlesnakes with 3 sections in their rattles each, and conclude that they are equal in age. But if one had plentiful food and the other didn't, then the time between molting could be completely different for the two of them, making the inference that they are the same age completely unreliable. The inference might be correct, but it would be blind luck if it is. By definition, that's not a reliable method!

Given what I said, issues about "commonsense assumptions" aren't relevant to why answer choice (E) is an assumption necessary for the argument, as you can see.

Robert Carroll