-all specific differences in consciousness must be conceived
as differences in degree, all higher mental processes and states, including
thought, as the perceptions and experiences, transformed according to
law, of beings which feel, have wants, possess memory, and are capable of
spontaneous motion. The subject coincides with its feeling of pleasure and
pain, from which sensation is distinguished by its objective content. The
illusions of metaphysics are scientifically untenable and practically
unnecessary. Various yearnings, wants, presentiments, hopes, and fancies,
it is true, lead beyond the sphere of that which can be checked by sense
and experience, but for none of their positions can any sufficient proof be
adduced. As physics has discarded transcendent causes and learned how to
get along with immanent causes, so ethics also must endeavor to establish
the worth of moral good without excursions into the suprasensible. The
ethical obligations arise naturally from human relations, from earthly
needs. The third volume of Laas's work differs from the earlier ones by
conceding the rank of facts to the principles of logic as well as to
perception. Aloys Riehl opposes the theory of knowledge (which starts from
the fundamental fact of sensation) as scientific philosophy to metaphysics
as unscientific, and banishes the doctrine of the practical ideals from the
realm of science into the region of religion and art. Richard Avenarius
defends the principle of "pure experience." Sensation, which is all that is
left as objectively given after the removal of the subjective additions,
constitutes the content, and motion the form of being.

[Footnote 1: Laas: _Idealism and Positivism_, 1879-84. Riehl:
_Philosophical Criticism_, 1876-87; Address _On Scientific and Unscientific
Philosophy_, 1883. Avenarius (p. 598): _Philosophy as Thought concerning
the World according to the Principle of Least Work_, 1876; _Critique of
Pure Experience_, vol. i. 1888, vol. ii. 1890; _Man's Concept of the
World_, 1891. C. Goering (died 1879; _System of Critical Philosophy_, 1875)
may also be placed here.]

With the neo-Kantians and the positivists there is associated, thirdly, a
coherent group of noetical thinkers, who, rejecting extramental elements of
every kind, look on all conceivable being as merely a conscious content.
This monism of consciousness is advocated by W. Schuppe of Greifswald (born
1836; _Noetical Logic_, 1878), J. Rehmke, also of Grei