#18 - Herbalist: Many herbal medicines work best when they

[Administrator]

Please post your questions below! Thank you!

[lathlee]

Hi. according to the three quirks of Assumption Q, I guess a) or b) is the right answer (starting with at least one or some) but I simply don't understand how negation of A) hurts the conclusion.

[chian9010]

I originally chose A but changed it to E... because I think that the assumption should be that skipping one's usual does for a day or two can indeed reduce the toxic effect. Is E wrong because it said "only if?"

I know if we use Assumption negation to negate A which becomes "No one who use herbal medicines daily use them for periods long enough for medicines to have side effect" would totally weaken the conclusion.

but how to negate E?

[Malila Robinson]

Hi Lathlee,
Answer A is correct, and the negation would be: None of the people who use herbal medicines daily use them for periods long enough for the medicines to have side effects. That negation hurts the conclusion which states that: "...at least some people who use herbal medicines daily should occasionally skip their usual dose for a day or two, to give the body a chance to recuperate."

The explanation for how the negation hurts the argument is that if no one uses the herbal medicine for extended periods of time then there is no reason (in this argument) that would support the need for some people to occasionally skip a dose for a couple of days.
Hope that helps!
-Malila

[Lily123]

I originally chose A but changed it to E... because I think that the assumption should be that skipping one's usual does for a day or two can indeed reduce the toxic effect. Is E wrong because it said "only if?"

Chian - I did the same thing. I think the reason (E) is wrong is because the author doesn't NEED to assume that THE ONLY reason to skip a dose is to reduce the side effects. I'm still having trouble wrapping my head around it though.

I understand how the negation of (A) would hurt the argument: if no one took any of the meds long enough to have side effects, then the advice would be pointless. But (E) negated says: If one occasionally skips a dose, it will NOT reduce toxic side effects. I thought this ACTUALLY destroyed the conclusion whereas the negation of (A) just says the advice potentially never applies to anyone, which is why I changed my answer.

I think I may have negated (E) wrong because of the word "should". Maybe the correct negation is: If one SHOULD occasionally skip a dose, then it will NOT reduce side effects. Which doesn't make much sense to me as a sentence, so I'm not sure.

Can one of our LSAT geniuses please weigh in on this?

[Adam Tyson]

Hey Lily123, let me see if I can help with the negation of answer E here. The key is the word "only", a necessary condition indicator, and we could take a formal conditional reasoning approach by saying that the supposed necessary condition is not, in fact, necessary. But instead, I will try a more holistic approach.

The answer is saying that reducing toxic side effects is the only reason why someone should skip a daily dose once in a while. To negate that, we would say that is NOT the only reason. Maybe there are other reasons for occasionally skipping a daily dose, such as:

doing so might save money

Sometimes the daily dose upsets the stomach (not a toxic side effect, just an unpleasant one)

It gives you bad breath, and you're going on a job interview or a date

Your religious practices require you to take no herbal medicine on the sabbath

and so on, and so on, etc.

If there is ANY other reason for sometimes skipping the daily dose, besides avoiding toxic side effects, that would still allow the argument to be valid (and these all do allow the argument to be valid), then answer E is NOT a necessary assumption of the argument. The author could still be correct that many people who take an herbal medicine daily should skip a dose once in a while to avoid toxic side effects, even if that is not the only reason for doing so.

Negate any conditional answer by showing that the supposed necessary condition is not, in fact, necessary, and then see what that does to the original argument.