Unlike the physical sciences, the behavioral disciplines offer no absolutes. On practically any issue, "scientific" evidence is used to support diametrically opposite points of view. Take vasectomy, for example. According to one recently reported investigation, this procedure for male sterilization (in which the tubes that transport sperm are severed) makes sex more pleasurable and marriage happier. According to another, the operation can lead to less satisfying sex, and ultimately to separation and divorce.
The favorable findings come from the Midwest Population Center of Chicago, a nonprofit medical organization that does nothing but perform...