Q20 - Researcher: We have found that

[TaeC572]

For some people who are overwhelmed by numerous long explanations for answer choice (D), hopefully mine helps.

Negation of (D): All conditions treatable by medicine are also treatable with stress reduction.

Hypothetical case:
1) High blood pressure is caused by aging (not stress!) and it is treatable with medicine. Therefore, it is also treatable by stress reduction.

2) The fact that it is treatable by stress reduction does not attack the conclusion - some HBP is not caused by stress (It is Aging! Sad story though...)

- Since the negation does not attack the conclusion, not the correct necessary assumption.

[LolaC289]

I think if we paid attention to the "only" in the premise, it would be easier to get rid of (D) and choose (E).

The argument is perfectly diagramed in previous posts. I'll still add my own:

PRE1: Any illness caused by stress ---> Treatable only by reducing stress

PRE2: But some HBP cases are effectively treated with Medicine

CON: Some HBP cases are definitely not caused by stress

Now this conclusion is very strong. In order to say it with confidence, we need something to trigger the contrapositive of PRE1, which is some HBP cases are not only treatable by reducing stress.

But what we have at hand is just some medicines proven to be efficient in treating HBP.

To make these medicines our friend, we need something to say these medicines does not also work by reducing stress.

(E) is the one that does this. Negate it, if these medicines reduce stress themselves, then we can't be sure they not working by reducing stress.

(D), super tempting, however, does not destroy the conclusion. Negate it, ALL conditions (HBP being one of them) that are treated effectively by medicines ARE ALSO treatable through reducing stress.

So what?

We only need reducing stress to not be the only way to treat our illness, to trigger the contrapositive!

Look at PRE1 again:
Any illness caused by stress ---> Treatable only by reducing stress

Now that we have HBP is treatable by reducing stress, have we destroyed the author's conclusion, that now, HBP is caused by stress?

No. Because if HBP is caused by stress, follow PRE1, it is treatable only by reducing stress. But we don't know if reducing stress is the only way to do it.

In other words, you can treat HBP by reducing patients' stress as you want, as long as we have some efficient medicines that does not also work by reducing stress, we get the contrapositive of PRE1, and safely land at the author's conclusion that some HBP is not caused by stress.

[SeyoungK790]

Using the method of LG,
I simply deduced the formula as below

The method to use here :
A->B
C-> not B
Then A and B cannot both exist

The author presumes the validity of his or her argument; the author thinks the argument is flawless
So we should find what the author implies to successfully complete the argument for it to be perfect.

Some HBP is x Ttable by r/d of stress
Illness caused by stress -> Ttable by r/d of stress
=> Some HBP must not be caused by stress

For this argument to be correct, we have to imply that being Ttable with medicine = x Ttable by reduction of stress