In exactly the same way as the idea of mechanicalism, so also that of
psychism is employed in a three-fold divergent sense. As in the former
case _motion_, so here _feeling_ is conceived, now as a universal
world-principle, now simply as a vital activity of all organisms, now
simply as the particular mental activity of man.
_A._ In its widest sense: _Panpsychism_. All matter is ensouled, because
all natural bodies known to us possess determinate chemical properties,
that is to say react uniformly and by law when subjected to the
determinate chemical (i. e. molecular-mechanical) influences of other
bodies: _chemical affinity_. Simplest example: sulphur and quicksilver
rubbed together form cinnabar, a new body of entirely different
properties. This is possible only on the supposition that the molecules
(or atoms) of the two elements if brought within the proper distance,
mutually _feel_ each other, by attraction move towards each other; on the
decomposition of a simple chemical compound the contrary takes place:
repulsion. (Empedocles’s doctrine of the “love and hatred of atoms.”)
_B._ In its more restricted sense: _Biopsychism_. The _organisms_ alone
are regarded as “ensouled,” because here the chemical processes are
more complicated and more striking (producing motions in cyclically
repeated succession) than in the case of the so-called “dead matter” of
the inorganic bodies. In particular does organic “irritability” appear
here as a higher form of the physical reaction called “_Auslösung_”
[the setting free, disengagement], and “soul-activity” (reflexes)
again as a higher form of irritability. However, all the phenomena
of organic life ultimately admit of being reduced to “mechanical”
(or “physico-chemical”) processes that differ from the processes of
the inorganic world only in point of degree or quantitatively, not
qualitatively. (“General Morphology,” I, Chap. V; VII, pp. 109-238.
“Natural Creation,” VIII, First Edition, Lecture XV.)
_C._ In its narrowest sense: _Zoopsychism_. Irritability, or universal
organic soul-activity, such as is the attribute of all organisms,
(identical with “life,”) reaches a higher stage through abstraction,
through the formation of _ideas_. _Feeling_ and _will_ become more
distinctly separated. This real soul-life, which is the attribute only
of the higher animals, passes through a long succession of different
stages of development, the most perfect of which is the soul of man.
The so-called “freedom of the will” is apparent only, as each single
volitional action is determined by a chain of precedent actions which
ultimately rest either upon _heredity_ (propagation) or upon _adaptation_
(nutrition). As these last are (“mechanically”) reducible to molecular
motions, the same also holds true of the former.