实际上，在意义实体的树形图上与在波菲利的树形图上一样，有些项目很难在两枝之间划出一个绝对的次范畴，例如“可感知实体”中“冷”、“热”、“黑”、“白”固然是可感知的，但“冷酷”、“热爱”、“黑暗（的年代）”、“白白（浪费体）”又具有属于不可感知的抽象性质，可以归入“非物质实体”次范畴。发生这种现象是什么原因呢？原因在语言的人文性和意义的人文性在语言中永远存在着不能用弗雷格式的泾渭分明的界线划分的领域和范畴。奎因也是逻辑实证主义者，但他看到了这一点，才在六十年代转向柏拉图的实在论立场，提出“对本体论的承诺”的前提，也是明智的抉择。他将“类”（Class）的概念引入实体(实在论）领域，从而厘清描述性抽象实体的意义。他以humble及humility为例解释说：

One might, with laudably scientific motives, resolve to sweep these abstract objects aside. One might begin by explaining "Humility is a virtue" and "Redness is a sign of ripeness" away as perverse ways of saying of humble concrete persons and red concrete fruits that they are virtuous and ripe. But such a program cannot without difficulty be carried far. What of "Humility is rare"? We may for the sake of argument construe "Humility is a virtue" and "Humility is rare" as "Humble persons are virtuous" and "Humble persons are rare"; but the similarity is misleading. For whereas "Humble persons are virtuous" means in turn that each humble person is virtuous, "Humble persons are rare" does not mean that each humble person is rare; it means something rather about the class of humble persons, viz., how small a part it is of the class of persons. But these classes are abstract objects in turn—not to be distinguished from attributes, save on a certain technical point ... So "Humble persons are

rare," unlike "Humble persons are virtuous," has only the appearance of concreteness; "Humility is rare" is the more forthright rendering. Maybe this abstract reference can still be eliminated, but only in some pretty devious way.

这样，那些诸如描述性形容词的“不可感知的抽象对象”，就如理论实体、虚拟实体一样，汇入了非物质实体，是其中的一个“类”，从而进入了实义实体的树形图。

责任编辑：admin