"Natural kind" is an intellectual grouping, or categorizing of things, in a manner that is reflective of the actual world and not just human interests. Some treat it as a classification identifying some structure of truth and reality that exists whether or not humans recognize it. Others treat it as intrinsically useful to the human mind, but not necessarily reflective of something more objective. Candidates examples of natural kinds are found in all the sciences, but the field of chemistry provides the paradigm example of elements.

John Dewey held a view that belief in unconditional natural kinds is a mistake, a relic of obsolete scientific practices.^: 419–24 W. V. O. Quine and Hilary Kornblith held the view that natural kinds are the unchanging structure of truth and reality. Hilary Putnam rejects descriptivist approaches to natural kinds with semantic reasoning. Hasok Chang and Rasmus Winther hold the emerging view that natural kinds are useful and evolving scientific facts.