 Church argues that the paradox is a special case of what is now known as “Frege’s Puzzle”. It is unclear how a statement of the form \(a = b\) can be both true and informative; for if it is true, then it would seem to say the same thing as \(a = a\), since this is the result of substituting \(a\) for \(b\) in \(a = b\). Moreover, Church views (2) as a special case of an informative identity statement, with the difference that (2)—unlike a statement of the form \(a = a\) that asserts the identity of objects—asserts the identity of concepts or senses. That is, Church takes “brother” and “male sibling” to designate concepts in the context of (2), rather than classes, since (2) is meant to be an analysis. Further, while “brother” and “male sibling” designate the same concept, viz. brother or male sibling, they may nevertheless differ in sense (that is, though they designate the same concept the express, they express different concepts as senses); and this is what explains how (2) can be informative and how the proposition expressed by (2) can differ from that expressed by the trivial \(b = b\) or \(\textit{ms} = \textit{ms}\).