Modality effects the transition to the forms of logical thought. On
the whole, Trendelenburg's unique fact of motion seems rather a
blunder. There is much more involved than he is willing to allow, and
motion _per se_ is by no means adequate to self-consciousness. His
theory has found little favour.

Ulrici.

Hermann Ulrici works out a system of the categories from a
psychological or logical point of view. To him the fundamental fact of
philosophy is the distinguishing activity (_unterscheidende
Tatigkeit_) of thought. Thought is only possible by distinction,
difference. The fixed points in the relations of objects upon which
this activity turns are the categories, which may be called the forms
or laws of thought. They are the aspects of things, notions under
which things must be brought, in order to become objects of thought.
They are thus the most general predicates or heads of predicates. The
categories cannot be completely gathered from experience, nor can they
be evolved a priori; but, by attending to the general relations of
thought and its purely indefinite matter, and examining what we must
predicate in order to know Being, we may attain to a satisfactory
list. Such a list is given in great detail in the _System der Logik_
(1852), and in briefer, preciser form in the _Compendium der Logik_
(2nd ed., 1872); it is in many points well deserving of attention.

Renouvier, Cousin, Hamilton, Mill.

The definition of the categories by the able French logician Charles
Bernard Renouvier in some respects resembles that of Ulrici. To him
the primitive fact is Relation, of which all the categories are but
forms. "The categories," he says, "are the primary and irreducible
laws of knowledge, the fundamental relations which determine its form
and regulate its movements." His table and his criticism of the
Kantian theory are both of interest.[12] The criticism of Kant's
categories by Cousin and his own attempted classification are of no
importance. Of little more value is the elaborate table drawn out by
Sir W. Hamilton.[13] The generalized category of the _Conditioned_ has
but little meaning, and the subordinate categories evolve themselves
by no principle, but are arranged after a formal and quite arbitrary
manner. They are never brought into connexion with thought itself, nor
could they be shown to spring from its nature and relations. J.S. Mil