柯靈烏在《哲學方法論》中主張哲學思維是定言的，並認為這就是存有學論證的真正內涵。本文主張：存有學論證事實上是「本質包含存在的存有物」之概念的語義分析，然而柯靈烏有關哲學思維的定言性的命題，根據的是哲學概念所指涉的對象的結構；柯靈烏稱其對象為哲學物類，它是包含不同的殊種於其下的物類，並且殊種具有形式之層級的結構。哲學物類具有此一結構，因為作為哲學思維的對象，它就是在不同思維、亦即不同的理論之間的衝突之中被構成的。

R. G. Collingwood maintains in An Essay on Philosophical Method that the philosophical thinking is categorical and claims that this is the real import of the ontological argument. In this paper, it is argued that, whereas the ontological argument is a semantic analysis of the concept of an entity whose essence contains existence, Collingwood’s thesis of the philosophical thinking’s categoricality is based upon the structure of the object referred to by a philosophical concept. Collingwood names the object philosophical genus, which is a genus with species falling under it that are ordered in a scale of forms. The philosophical genus has such a structure because, as the object of philosophical thinking, it is formed in the conflicts among different thinking or theories.