the ground of the unity. Why are things essentially like
one another? How is the unity maintained? How is it continued? Where
does the common pattern come from? The question of the nature of
the Universal thus links itself with metaphysical theories of the
construction of the world, or even with the Darwinian theory of the
origin of species.

Passing by these remoter questions, we may give the answers of
the three extreme schools to the ontological question, What is a
Universal?

The answer of the Ultra-Realists, broadly put, was that a Universal is
a substance having an independent existence in nature.

Of the Ultra-Nominalists, that the Universal is a name and nothing
else, _vox et praeterea nihil_; that this name is the only unity among
the individuals of a species, all that they have in common.

Of the Ultra-Conceptualists, that the individuals have more in common
than the name, that they have the name plus the meaning,
_vox_ + _significatio_, but that the Universals, the genera and
species, exist only in the mind.

Now these extreme doctrines, as literally interpreted by opponents,
are so easily refuted and so manifestly untenable, that it may be
doubted whether they were ever held by any thinker, and therefore I
call them Ultra-Realism, Ultra-Nominalism, and Ultra-Conceptualism.
They are mere exaggerations or caricatures, set up by opponents
because they can be easily knocked down.

To the Ultra-Realists, it is sufficient to say that if there existed
anywhere a substance having all the common attributes of a species
and only these, having none of the attributes peculiar to any of the
individuals of that species, corresponding to the general name as an
individual corresponds to a Proper or Singular name, it would not be
the Universal, the unity pervading the individuals, but only another
individual.

To the Ultra-Nominalists, it is sufficient to say that the individuals
must have more in common than the name, because the name is not
applied arbitrarily, but on some ground. The individuals must have in
common that on account of which they receive the common name: to call
them by the same name is not to make them of the same species.

To the Ultra-Conceptualists, it is sufficient to say that when we
employ a general name, as when we say "Socrates is a man," we do
not refer to any passing thought or state of mind, but to certain
attributes independent of what is passing in our minds. We cannot make
a thing