Of patients over 65 years old who survived coronary bypass

Whenever we're asked to WEAKEN an argument, we must find the LOGICAL FLAW that exists between the premises and the conclusion.

Premise:
Of patients over 65 years old who survived coronary bypass surgery... only 75 percent benefited from the surgery

Conclusion:
Thus it appears that for one in four such patients, the doctors who advised them to undergo this surgery, with its attendant risks and expense, were more interested in an opportunity to practice their skills and in their fee than in helping the patient.

Logical flaws:
- did the doctors of those 25% of patients know that surgery would be unhelpful in their particular case? If doctors had no idea beforehand which patients would be helped and which wouldn't, then they could recommend surgery with the hope of helping every time.
- do we know that the doctors were the sole decision-makers? Maybe insurance companies or hospital procedures dictated that doctors should recommend surgery in more cases than would be helpful. This would indicate a reason other than skill-practicing or money.
- do we know that doctors need to practice their skills, or that they get more money? If either of these were untrue, it would undermine the causation in this argument.

We want to choose an answer that attacks one of these logical flaws.

A. Many of the patients who receive coronary bypass surgery are less than 55 years old.
Irrelevant. The argument is only concerned with patients who are 65+.

B. Possible benefits of coronary bypass surgery include both relief from troubling symptoms and prolongation of life.
The argument is all about people who did not benefit from surgery, and the intentions of the doctors. It doesn't really matter what the benefits actually were.

C. Most of the patients in the survey decided to undergo coronary bypass surgery because they were advised that the surgery would reduce their risk of future heart attacks.
This speaks to the patients' motivation, but doesn't do anything to weaken our conclusion about the doctors' motivation.

D. The patients over 65 years old who did not benefit from the coronary bypass surgery were as fully informed as those who did benefit from the surgery as to the risks of the surgery prior to undergoing it.
Again, this does nothing to undermine the conclusion about the intentions of the doctors. This could be true and the conclusion could still hold.

E. The patients who underwent coronary bypass surgery but who did not benefit from it were medically indistinguishable, prior to their surgery, from the patients who did benefit.
Correct! If the patients are indistinguishable, then doctors wouldn't know ahead of time who was going to benefit and who wasn't. Therefore, we can't assume any ill-intent in recommending surgery to those who end up not benefitting.

The answer is E.