The question whether a prop. has
Sinn
sense
can never depend on the truth of another prop. about a constituent of the first. E.g. the question whether (x). x = x has
Sinn
meaning
can't depend on the question whether (∃x). x = x is true. It doesn't describe reality at all, & deals therefore solely with symbols; n it says that they must symbolise, but not what they symbolise.

  It's obvious that the dots & brackets are symbols, & obvious also that they haven't any independent meaning. You must therefore, in order to introduce so called “logical constants” properly, introduce the general notion of all possible combinations of them


–t = the general form of a prop. You thus introduce both a–b functions, identity & universality (the 3 fundamental constants) simultaneously.