Theories which make a proposition of logic appear
substantial are always false. Once could e.g. believe
that the words "true" and "false" signify two properties among
other properties, and then it woud appear as a remarkable fact
that every proposition possesses one of these properties. This
now by no means appears self-evident, no more so than the
proposition "All roses are either yellow or red" would seem
even if it were true. Indeed our proposition now gets quite
the character of a proposition of natural science and this is
a certain symptom of its being falsely understood.
It is the characteristic mark of logical propositions
that one can perceive in the symbol alone that they are true;
and this fact contains in itself the whole philosophy of
logic. And so also it is one of the most important facts that
the truth or falsehood of non-logical propositions can
not be recognized from the propositions alone.