IDEALISM AND REALISM.
We have now reached a point of divergence in the development of
philosophy. Descartes had affirmed and attempted to mediate the
opposition, between thought and being, mind and matter. This mediation,
however, was hardly successful, for the two sides of the opposition he
had fixed in their widest separation, when he posited them as two
substances or powers, which reciprocally negated each other. The
followers of Descartes sought a more satisfactory mediation, but the
theories to which they saw themselves driven, only indicated the more
clearly that the whole premise from which they started must be given up.
At length Spinoza abandoned the false notion, and took away its
substantiality from each of the two opposed principles. Mind and matter,
thought and extension, are now one in the infinite substance. Yet they
are not one _in themselves_, which would be the only true unity of the
two. That they are one in the substance is of little avail, since they
are indifferent to the substance, and are not immanent distinctions in
it. Thus even with Spinoza the two remain strictly separate. The ground
of this isolation we find in the fact that Spinoza himself did not
sufficiently renounce the Cartesian notion, and thus could not escape
the Cartesian dualism. With him, as with Descartes, thought is _only_
thought, and extension _only_ extension, and in such an apprehension of
the two, the one necessarily excludes the other. If we would find an
inner mediation for the two, we must cease to abstract every thing
essential from each. The opposite sides must be mediated even in their
strictest opposition. To do this, two ways alone were possible. A
position could be taken either on the material or on the ideal side, and
the attempt made to explain the ideal under the material, or the
material under the ideal, comprehending one through the other. Both
these attempts were in fact made, and at about the same time. The two
parallel courses of a one-sided _idealism_, and a one-sided _realism_
(Empiricism, Sensualism, Materialism), now begin their development.