"Philosophical classifications are not like labels for political parties that people officially join; at best, they point to a salient feature that systems that differ in many other ways have in common. Such groupings fail to rise to the level of natural kinds; they are closer to what Wittgenstein thought of as concepts based upon family resemblances. They should be understood as handy devices for abbreviated referenced rather than as the product of a deep analysis of a philosophical tendency.

Charles Landesman, Skepticism – The Central Issues, 2.