Akela wrote:
Physician: In an experiment, 50 patients with chronic back pain were divided into two groups. Small magnets were applied to the backs of one group; the other group received no treatment. Most of the patients in the first group, but very few in the second group, reported a significant reduction in pain. This shows that magnetic fields are probably effective at relieving some back pain.
Which one of the following, if true, constitutes the logically strongest counter to the physician’s argument?
(A) A patient’s merely knowing that a treatment has been applied can lead to improvement in his or her condition.
(B) Most physicians believe that medication relieves chronic back pain more effectively than magnets do.
(C) No other experiments have been done showing that magnetic fields reduce pain in any area other than the back.
(D) Some of the scientists who helped design the experiment believed even before the experiment that magnetic fields relieve back pain, but they were not directly involved in conducting the experiment.
(E) There was wide variation in the specific causes of the chronic back pain suffered by the patients in the experiment.
Small magnets were applied to one group. Most of them reported significant improvement.
No treatment was given to the other group. Very few reported improvement.
Conclusion: This shows that magnetic fields are probably effective at relieving some back pain.
We need to weaken the conclusion. The conclusion certainly seems reasonable, right? Those with magnet reported less pain while others didn't so it seems magnets helped. But we need to weaken the conclusion. Something should say that it may not have been the magnets that helped but something else that happened in group 1.
(A) A patient’s merely knowing that a treatment has been applied can lead to improvement in his or her condition.
This could be the "something else" that helped group 1 people. If merely knowing that a treatment has been applied (placebo effect) can reduce the sensation of pain, the magnets may have had nothing to do with the improvement. It may be the impact of knowing that they were treated. While group 2 people did not get any treatment and hence did not get this psychological reassurance that they were treated. Hence they did not claim a reduction in pain.
(B) Most physicians believe that medication relieves chronic back pain more effectively than magnets do.
What is more effective than magnets is irrelevant. Our conclusion just says that magnets have some impact.
(C) No other experiments have been done showing that magnetic fields reduce pain in any area other than the back.
Areas other than the back are irrelevant. The conclusion only talks about back pain.
(D) Some of the scientists who helped design the experiment believed even before the experiment that magnetic fields relieve back pain, but they were not directly involved in conducting the experiment.
Scientists involved are irrelevant.
(E) There was wide variation in the specific causes of the chronic back pain suffered by the patients in the experiment.
Causes of back pain does not matter. Most people claimed a reduction in pain so whatever worked, worked for most people.
Answer (A)