propositions, we must be able to say all at once . An elementary
proposition really contains all logical operations in itself. For 'fa' says
the same thing as '(dx) . fx . x = a' Wherever there is compositeness,
argument and function are present, and where these are present, we already
have all the logical constants. One could say that the sole logical
constant was what all propositions, by their very nature, had in common
with one another. But that is the general propositional form.


5.471 The general propositional form is the essence of a proposition.


5.4711 To give the essence of a proposition means to give the essence of
all description, and thus the essence of the world.


5.472 The description of the most general propositional form is the
description of the one and only general primitive sign in logic.


5.473 Logic must look after itself. If a sign is possible , then it is also
capable of signifying. Whatever is possible in logic is also permitted.
(The reason why 'Socrates is identical' means nothing is that there is no
property called 'identical'. The proposition is nonsensical because we have
failed to make an arbitrary determination, and not because the symbol, in
itself, would be illegitimate.) In a certain sense, we cannot make mistakes
in logic.


5.4731 Self-evidence, which Russell talked about so much, can become