In books on logic, no variables ought to occur, but only the general
propositions which justify the use of variables.
It follows that the so-called definitions of logic are not
definitions, but only schemes of definitions, & instead of these we
ought to put general propositions; & similarly the
so-called primitive ideas (Urzeichen) of logic
are not primitive ideas, but the schemes of them.
The mistaken idea that there are things called facts or complexes
& relations easily leads to the opinion that there must be a
relation of questioning to the facts, & then the question arises
whether a relation can hold between an arbitrary number of things, since a
fact can follow from arbitrary cases.
It is a fact that the proposition which e.g.
expresses that
q follows from
p
& p ⊃ q is this:
p.p ⊃ q. ⊃
p.q.q.
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