But the greater part of these dissensions, which have existed for centuries and are yet living, rests on the confusion between concepts and pseudoconcepts, and the consequent pretension to define the concept by denying one or other of these two forms. This is the origin of the two opposite schools of _realists_ and _nominalists,_ which are also called in our times rationalists and empiricists (arbitrarists, conventionalists, hedonists). The realists maintain that concepts are real: that they correspond to reality; the nominalists, that they are simple names to designate representations and groups of representations, or, as is now said, tickets and labels placed upon things in order to recognize and find them again. In the former case, no elaboration of representations higher than the universalizing act of the concept is possible; in the latter, the only possible operation is that which has already been described--mutilation, reduction and fiction, directed to practical ends.
The consequence of these one-sided affirmations has been that the realists have defined as concepts, and therefore as having a universal character, all sorts of rough pseudoconcepts; not only the horse, the artichoke and the mountain, but also, logically, the table, the bed, the seat, the glass, and so on; and they have exposed themselves from the earliest beginnings of philosophy to the sarcastic and irresistible objection that the horse exists, but not horsiness, the table, but not tabularity. This conceptualization of pseudoconcepts is the error of which they have really been guilty, not that of conferring empirical reality on the concepts by placing them as single things alongside of other things, an extravagance which it is doubtful if any man of moderate sense has ever seriously committed. The realists who rendered the concepts real in this sense at the same time rendered them unreal, that is to say, single and contingent, and in need of being surpassed by true concepts. The nominalists, on the other hand, considered as arbitrary and mere names all the presuppositions of their mental life--being and becoming, quality and final cause, goodness and beauty, the true and the false, the Spirit and God. Without being aware of it, they have fallen into inextricable contradictions and into logical scepticism.