. Therefrom he infers that the theory of relativity is contrary to logic and is a manifest absurdity. And yet, if we examine these statements carefully, we shall have no difficulty in seeing that the error in logical reasoning lies not with Einstein but with the critic himself.
In order to dispel any doubt on this score, let us ask the critic what he intends to convey by the symbol =. Suppose, for example, that we are considering two objects,
and
, of the same size. Are we entitled to write
? The answer should be: Yes, if the symbol = stands for “is of the same size as”; or No, if it stands for most other types of identity. In order to avoid confusion let us then represent the symbol by
(