arther than this. One may say: How can I know that
even the extension, number, and motion of the things which I directly
perceive have corresponding to them extension, number, and motion, in
an outer world? If what is not colored can cause me to perceive color,
why may not that which is not extended cause me to perceive extension?
And, moved by such reflections, one may maintain that there exists
outside of us that which we can only characterize as an Unknown Cause,
a Reality which we cannot more nearly define.

This last position resembles very closely one side of Spencer's
doctrine--that represented in the last of the two citations, as the
reader can easily see. It is the position of the follower of Immanuel
Kant who has not yet repudiated the noumenon or thing-in-itself
discussed in the last chapter (section 51).

I am not concerned to defend any one of the varieties of Direct or of
Hypothetical Realism portrayed above. But I wish to point out that
they all have some sort of claim to the title _Realism_, and to remind
the reader that, when we call a man a realist, we do not do very much
in the way of defining his position. I may add that the account of the
external world contained in Chapter IV is a sort of realism also.

If this last variety, which I advocate, _must_ be classified, let it be
placed in the first broad class, for it teaches that we know the
external world directly. But I sincerely hope that it will not be
judged wholly by the company it keeps, and that no one will assign to
it either virtues or defects to which it can lay no just claim.

Before leaving the subject of realism it is right that I should utter a
note of warning touching one very common source of error. It is
fatally easy for men to be misled by the names which are applied to
things. Sir William Hamilton invented for a certain type of
metaphysical doctrine the offensive epithet "nihilism." It is a type
which appeals to many inoffensive and pious men at the present day,
some of whom prefer to call themselves idealists. Many have been
induced to become "free-willists" because the name has suggested to
them a proper regard for that freedom which is justly dear to all men.
We can scarcely approach with an open mind an account of ideas and
sensations which we hear described as "sensationalism," or worse yet,
as "sensualism." When a given type of philosophy is set down as
"dogmatism," we involuntarily feel a prejudice against it.