There does not exist at the present time any comprehensive and consistent theory of knowledge which has been generally accepted. This is particularly regrettable in view of the fact that the area of reference is an empirical one. Perhaps the reason for the lack is twofold. The philosophers for the most part pursue their investigations into the topic in some disregard of what the scientists are doing. As for the scientists themselves, so many specialties are involved that no professional effort is made to put the results together. The findings are perhaps changing too much for anyone to undertake the framing of a single hypothesis which could account not only for all of the significant data but also for many of the lesser theories.