Yet there may be limits to what science can do. Consider this question: Can science disprove ghosts? In the supremely confident period, toward the end of the last century, when it was supposed that there was a conflict between Science and Religion, and Science was rapidly winning, it was the mark of an educated man to say “Science has proved that there are no such things as ghosts, they are merely the superstitions of the unenlightened.” Education is always behind the times, and much the same attitude is prevalent today; you can still hear people say, “Surely, science has proved that there are no ghosts.” And yet, is that so? Suppose, just suppose for the sake of argument, that ghosts can occasionally appear when the psychological conditions are just right, and suppose, what might quite well be true, that one necessary condition for the appearance of a ghost is the absence of a scientist: well then, “Science” (that is to say, scientists) would go on investigating ghost after ghost, and would “disprove” every one of them, and yet ghosts would continue to appear whenever the scientists were not looking. This is a simple case, perhaps not a very important one, illustrating the impossibility of proving anything negative by the scientific method. At least it is enough to show that science is not infallible, and if science has any more serious defects than the inability to perceive an occasional spook in the corner, it is of the utmost importance that citizens, generally, should know what they are. Yet this sort of knowledge is very conspicuously absent from the populace at large and from the curriculums of institutes of learning. Non-scientists don’t even know what science can do; scientists are so obsessed with the past successes and future possibilities of their own specialty that they have no idea what the proper field of science in general is and no recognition that there are any limits. What they can’t do, some other scientists, presumably, can do, so that they come to think that science with a capital “S”—or rather its concentrated and distilled essence, the Scientific Method—is the universal cure-all for mankind.

In the third and fourth paragraphs, the author discusses a case in order to demonstrate the confidence of scientists demonstrate the confidence of scientists A illustrate the limits of scientific claims illustrate the limits of scientific claims B show why scientists stopped believing in superstitions show why scientists stopped believing in superstitions C argue that people want to trust scientific thinking argue that people want to trust scientific thinking D present an example of a scientific investigation