fact, is unavailable in connexion with general truths; and logical
proof is obtainable only in that comparatively narrow sphere where
reasoning is based--as in mathematics--upon axioms, or--as in certain
really crucial experiments in the mathematic sciences--upon quasi-
axiomatic premisses.

Everywhere else we base our reasonings on premisses which are simply
more or less probable; and accordingly the conclusions which we arrive
at have in them always an element of insecurity.

It will be clear that in philosophy, in jurisprudence, in political
economy and sociology, and in literary criticism and such like, we are
dealing not with certainties but with propositions which are, for
literary convenience, invested with the garb of certainties.

What kind of logical sanction is it, then, which can attach to
reasonings such as are to be set out here?

They have in point of fact the sanction which attaches to reasonings
based upon premisses arrived at by the method of _diacritical
judgment._

It is, I hasten to notify the reader, not the method, but only the
name here assigned to it, which is unfamiliar. As soon as I exhibit it
in the working, the reader will identify it as that by which every
generalisation and definition ought to be put to the proof.

I may for this purpose take the general statements or definitions
which serve as premisses for my reasonings in the text.