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some quality common to them all that is peculiar
to them i.e. possessed by nothing else. Kant, I dare
say, would remark that this is a Regulative Principle
but that it cannot be proved to be a Constitutive
principle. That is, it is proper to assume it, but
you cannot prove it is so. But I reply that every
principle of logic is a Regulative Principle and nothing
more. Logic has nothing to do with Existence. And I
should add: Herr Professor Dr. Hofrath Kant, permit me
to say that in saying this is not a Constitutive principle
you speak of qualities as if they were existent individuals.
A quality has no other being in itself than
possibility and to say that a quality is possible
is to say that it has all the being that in the
nature of things a quality could have. If as you say there may be

30

some quality common to them all that is peculiar
to them i.e. possessed by nothing else. Kant, I dare
say, would remark that this is a Regulative Principle
but that it cannot be proved to be a Constitutive
principle. That is, it is proper to assume it, but
you cannot prove it is so. But I reply that every
principle of logic is a Regulative Principle and nothing
more. Logic has nothing to do with Existence. And I
should add: Herr Professor Dr. Hofrath Kant, permit me
to say that in saying this is not a Constitutive principle
you speak of qualities as if they were existent individuals.
A quality has no other being in itself than
possibility and to say that a quality is possible
is to say that it has all the being that in the
nature of things a quality could have. If as you say there may be