I believe individual scientists select a problem because they know its solution would be of considerable interest to them and, possibly, to other scientists and the general public. The practice of science is defined as the conduct of research, which includes theory, experimental design, observation, measurement, and interpretation and communication of results. Although there is undoubtedly a very large number of possible questions answerable by scientists, if we include all of scientific inquiry, with respect to the problem at hand the number of questions that can be put in the form of testable hypotheses is rather limited. Sometimes there is only one hypothesis under consideration when it has been accepted by a group of investigators as a satisfactory solution, and it becomes a "ruling...