Sutton's law states that in attempting to diagnose a problem, one should first do the experiment that can confirm the most likely diagnosis. It is taught in medical schools to guide new doctors in ordering tests in a way that leads to faster treatment, while minimizing unnecessary costs. It is also applicable to other disciplines, such as debugging computer programs.
A more thorough analysis will consider the false positive rate of the test and the possibility that a less likely diagnosis might have more serious consequences.
The law is named after the bank robber Willie Sutton, who supposedly answered a reporter inquiring why he robbed banks by saying "because that's where the money is." He later denied saying it, however.
A similar idea is contained in the physician's adage, "When you hear hoofbeats in Texas, think horses, not zebras."