Biological systematists in general and cladists in particular are currently struggling with the question: what is a paraphyletic group? This question historically succeeds the question: what is a species?, and arose in the moment biological systematists began to believe in “a true tree of life” (ie, a “tree” of “species”).
Both of these questions are, however, impossible to answer, because they are backwards, ie, rhetorical. They are analogous to if I should invent the new word “gump”, and then ask the question: what is a gump? This kind of question is normally used to support a particular line of reasoning by emphasizing a particular argument (then answered by the requester himself), but in this case the questions actually expresses a true inquiry. Biological systematists in general and cladists in particular do actually wonder what they have created. The answer is thus: you tell me. It is you that have invented the words, surely you must know what you mean with them. And, if you don’t, who can possibly do?
However, if I shall try to answer these questions on biological systematists in general and cladists in particular behalf, then my answer is that both “species” and “paraphyletic groups” are distinctions we make in the reality we see, and thus not things we see. Neither “species” nor “paraphyletic groups” are thus “real” things, but distinctions we make in the reality we see. And, the difference between reality and the reality we see is that the reality we see not is the reality, but the reality we see. Only if we conflate reality with the reality we see can we come up with these questions. These questions thus show that biological systematists in general and cladists in particular have conflated what there is with what we see, and that the questions thus only can be answered by them with what they see.
In a general sense, however, “species” are kinds, and “paraphyletic groups” (of “species”) are groups kinds that exclude the kind that conflates the kinds in the group (ie, “the ancestral species), whereas “clades” are groups of kinds that include the kind that conflates the kinds in the group (ie, “the ancestral species”*). Clades are thus fundamentally a conflation of what there is with what we see. The main problem with this conflation is that it leads straight into the race biology of nazism, It means that this issue is not only an academic matter, but rather of a much more fundamental meaning. If we yield to this conflation, then we actually yield to barbarism.