PT 80 -- Section 1-- Q5

KLoren23KLoren23 Core Member
in Logical Reasoning 22 karma

Is the correct negation for (B), “The leopard magpie moth does have the speed or agility to escape from SOME of its predators”? And if so, does this hinge on the fact that it contains the word “any”, which is treated like “all”, and therefore negated as “some is not”, and the added “not” creates a double negative which turns “does not” into “does”? If this is the case, I would like to know if this is a hard-and-fast rule we can apply every time we see the words “any”, “all”, “every”, “some”, or “most” anywhere in the answer choice of a necessary assumption question. I usually don’t have trouble negating these words when they are at the beginning of the sentence, as in “all swans are white”, but I had never negated an answer choice in this way when the quantifier was in the middle of the sentence. Consequently, like others, I thought the negation for this was “the leopard magpie moth does have the speed or agility to escape from ANY of its predators, which in my eyes, does undermine the argument. Any help would be greatly appreciated!

Comments

  • DINOSAURDINOSAUR Member
    edited June 2020 591 karma

    I think your negation of (B) is correct. To negate this sentence, I would think: It's not the case that the LM moth does not have the speed or agility to escape from any of its potential predators. So other cases are allowed, which means LM moth has the speed or agility to escape from some of its potential predators. I guess I'm thinking it in a continuous spectrum. As long as it's not that extreme case described in (B), all other cases are allowed.

    Additionally, even if you say "the leopard magpie moth has the speed or agility to escape from ANY of its predators", it does not make the argument fall apart. The argument assumes that having macrozamin in the moth's caterpillar stage is crucial for its survival, and Natal grass cycad is the only plant that give LM caterpillar this toxin. So even if the moth is always on alert and are able to run fast, if they die when they are caterpillars, they are still in danger of extinction.

    Hope it helps!

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