PT 63 Section 3 #11 (LR) Forum

[june2014]

I got down to (B) by POE, but I don’t see how it’s completely necessary to the argument.

Even if we negate (B), can’t the premise still support the conclusion?

There seems to be a leap from “people who rely on the web” (in the stimulus) to “people who don’t rely exclusively on scientifically valid information” (in answer choice B).

This is what I thought:

It could be that people who attempt to diagnose their medical conditions by relying on the web could be likely to do more harm than good to themselves, but people who attempt to diagnose their medical conditions by relying on scientifically invalid home remedies (not through the web) could be unlikely to do more harm than good. In this case if there is a larger number of people who rely on scientifically invalid home remedies than those who rely on the web, the negation of (B) could be true without destroying the argument.

Can anyone tell me where I’m going wrong?

[Paran0id Andr0id]

Post the question.

[Christine (MLSAT)]

From a purely practical perspective, I generally advocate that students simply look for the disconnect in terms before engaging in a serious negation test on promising answers.

Distilling the argument core here ends up like this:

• PREMISE: Web-browsers can't tell the difference btw valid science and other stuff
  CONCLUSION: Thus, self-diagnosing web-browsers who rely on web-info are more likely to do harm than good

The conclusion wants to get from 'self-diagnosing web-browsers relying on web-info' to 'more likely to do harm than good'.

If we wanted to make this argument work, first, we need to connect the 'self-diagnosing web-browsers relying on web-info' to the 'web-browsers who can't tell the difference between valid science and other stuff'. We'd need to assume that the self-diagnosers had the same issues with distinguishing information on the web, and that that sub-group of web-browswers relied, at least in part, on that 'other stuff' out there.

Now, let me stress that the argument *needs* to do that in order to be valid. But that's not all we'd need. Once we had that down, we'd need another connection between this group of [self-diagnosers that rely on some non-science] and the idea of [likely to do more harm than good]. It's this last connection that answer (B) connects. (B) indicates that if that group DOESN'T rely exclusively on science, i.e., if they rely even a little on anything else, then you are more likely to do harm than good.

We'd need both connections, and (B) only gives us one of them, which is why it's a necessary (and not sufficient) assumption.

Generally speaking, this follows a common, if confusing, format:

• PREMISE: B are C
  CONCLUSION: Therefore, A are D

The argument must be assuming that A are B AND ALSO that C are D in order to make the whole flow work. If we can see this structure, and recognize that the argument needs connections on both ends, the link-up in (B) starts to look a lot more attractive.

Now, about your negation test. Again, I'll stress that I highly recommend doing core breakdown and disconnect work before resorting to the negation test, for a variety of practical reasons. Negating this answer is negating a conditional, which often causes some confusion for people, and it would result in something like:

• If self-diagnosers rely on non-science, then we have no information about whether they are more likely to do harm than good.

Once we've broken that link-up, the premise cannot support the conclusion unless we inject more information. You're right that it's possible for the conclusion to still work if you know some other interesting and useful fact. But without that additional piece of information, this premise now can't be connected on its own, to the conclusion of 'likely to do more harm than good'.

This is the fundamental difference between the idea that a conclusion could still be TRUE in some universe, regardless of the premise and a conclusion that is supportable directly from the information in the premise. The fact that the conclusion could still be true (if we had more information) doesn't matter if it is no longer supportable from the premise itself.

Thoughts?

[june2014]

From a purely practical perspective, I generally advocate that students simply look for the disconnect in terms before engaging in a serious negation test on promising answers.

Distilling the argument core here ends up like this:

• PREMISE: Web-browsers can't tell the difference btw valid science and other stuff
  CONCLUSION: Thus, self-diagnosing web-browsers who rely on web-info are more likely to do harm than good

The conclusion wants to get from 'self-diagnosing web-browsers relying on web-info' to 'more likely to do harm than good'.

If we wanted to make this argument work, first, we need to connect the 'self-diagnosing web-browsers relying on web-info' to the 'web-browsers who can't tell the difference between valid science and other stuff'. We'd need to assume that the self-diagnosers had the same issues with distinguishing information on the web, and that that sub-group of web-browswers relied, at least in part, on that 'other stuff' out there.

Now, let me stress that the argument *needs* to do that in order to be valid. But that's not all we'd need. Once we had that down, we'd need another connection between this group of [self-diagnosers that rely on some non-science] and the idea of [likely to do more harm than good]. It's this last connection that answer (B) connects. (B) indicates that if that group DOESN'T rely exclusively on science, i.e., if they rely even a little on anything else, then you are more likely to do harm than good.

We'd need both connections, and (B) only gives us one of them, which is why it's a necessary (and not sufficient) assumption.

Generally speaking, this follows a common, if confusing, format:

• PREMISE: B are C
  CONCLUSION: Therefore, A are D

The argument must be assuming that A are B AND ALSO that C are D in order to make the whole flow work. If we can see this structure, and recognize that the argument needs connections on both ends, the link-up in (B) starts to look a lot more attractive.

Now, about your negation test. Again, I'll stress that I highly recommend doing core breakdown and disconnect work before resorting to the negation test, for a variety of practical reasons. Negating this answer is negating a conditional, which often causes some confusion for people, and it would result in something like:

• If self-diagnosers rely on non-science, then we have no information about whether they are more likely to do harm than good.

Once we've broken that link-up, the premise cannot support the conclusion unless we inject more information. You're right that it's possible for the conclusion to still work if you know some other interesting and useful fact. But without that additional piece of information, this premise now can't be connected on its own, to the conclusion of 'likely to do more harm than good'.

This is the fundamental difference between the idea that a conclusion could still be TRUE in some universe, regardless of the premise and a conclusion that is supportable directly from the information in the premise. The fact that the conclusion could still be true (if we had more information) doesn't matter if it is no longer supportable from the premise itself.

Thoughts?

This question was giving me a real headache but I think I get it now. Thank you so much!