“如果我们说,一条直线是指其空中的一道光线,或者指磨过的刀口,那末这条命题只有在我们提供出用以产生光线或者刀口的实际操作时才具有确切意义。”实演主义(Operationalism)本来是应用来解释测量的概念的,但是在这儿,我们看到弗兰克已经扩大了实演主义的应用范围,用来说明所有科学名词的意义了。我敢说弗兰克是以相当隐秘的方式指出科学的哲学中的 “If we say that a straight line refers to a ray of light in the sky or a worn edge, that proposition has its exact meaning only if we provide the actual operation for generating light or knives.” Realism (Operationalism) was originally used to explain the concept of measurement, but here we see that Frank has expanded the scope of the application of acting to illustrate the meaning of all scientific terms. I dare say that Frank points out the philosophy of science in a rather covert manner