Bauhaus-Universität Weimar

Dictionary of philosophy and psychology including many of the principal conceptions of ethics, logics, aesthetics ... and giving a terminology in English, French, German and Italian, vol. 2 [lead-zwing]
Baldwin, James Mark
associated with the first theory mentioned 
above are (a) that it is merely the original 
instability of protoplasm, or (b) that it is 
due—especially in the higher forms, as is 
seen in the plasticity of the brain substance— 
to natural selection, and is a necessity for 
ontogenetic development. The second theory 
given above—that of vitalism—holds that 
plasticity of the specific sort which it accepts 
is a funclamental property of life and explains 
phylogenetic evolution. 
It is probable—or possible—that there are 
two forms of plasticity : (a) that of the living 
cell wherever found, and of the lowest organ¬ 
isms, by which they respond to various sorts 
of stimulation; and (b) that of the differenti¬ 
ated and developed structures and organisms 
whose modifications and variations are within 
certain defined and well-marked limits for 
each. It is possible, indeed, that this latter 
case illustrates the natural selection of certain 
modifications, i. e. those which served useful 
ends. In this case the fixity of organic 
structure, together with its secondary plasti¬ 
city, has been acquired by the gradual re¬ 
striction of its original plasticity : thus, 
according to recent writers (Bailey, Williams, 
A. Sedgwick), heredity itself as a function 
may have arisen. There would seem, how¬ 
ever, to be no reason to doubt that both pro¬ 
cesses are true : (i) the gradual reduction of 
original plasticity and variability, securing 
certain great organic structural results from 
which,(2) as a basis,has arisen, through evolu¬ 
tion, the relative plasticity of brain, nerve, &c., 
which allows newer, and especially intelligent, 
Apart from vital plasticity in general, the 
facts of individual accommodation make the 
nature and limits of brain plasticity a matter 
of great interest. Plasticity underlies all 
acquisition—especially motor acquisition— 
and learning. As a matter of endowment, 
it is contrasted with the fixity of instinct 
and reflex action; a contrast which, on the 
psychological side, is seen in educability or 
the lack of it (see Education). Cf. Accom¬ 
modation (in biology and psychology). 
Literature: see Living Matter, Nerve 
Stimulation and Conduction, Accommoda¬ 
tion (in biology) ; see also Bibdiog. G, 2, f 
(J.M.B., E.B.P.) 
Plato. (429-348 B.c.) Son of Ariston; 
pupil of Socrates. At military age he probably 
took part in campaigns of the army. Draco 
and Epicharmus taught him music, or, at 
least, poetry. After the execution of Socrates 
(399 B.c.), he went to Megara and reviewed 
theEleatic doctrine; travelled in Ionia,Cyrene, 
and Egypt, later in Italy, where he learned 
more in regard to the Pythagoreans. Owing 
to a disagreement with the elder Dionysius in 
Syracuse, he was deprived of his liberty at 
Aegina. Upon recovering his freedom through 
the intervention of the Cyrenaic Anniceris, 
he returned to Athens, and opened his school. 
He made two fruitless journeys to Sicily, but 
aside from these he taught in Athens until 
his death. Born at Athens, his real name 
was Aristocles. See Socratics (Plato), and cf. 
Neo-Platonism, Greek Terminology, and 
the principal philosophical topics generally. 
Platonism : see Socratics (Plato). 
Play [AS. plegan, to play] : Ger. Spiel ; 
Fr .Jeu; Ital. giuoco. The exercise of any one 
of the functions of mind and body in a way 
usually covered by such expressions as * play 
is for its own sake/ ‘play is not serious,’ 
‘ play involves make-believe/ ‘ play is an in¬ 
dulgence and is contrasted with work/ i. e. 
with no conscious reason for it except the 
indulgence itself. 
These general characterizations serve to 
raise the question as to what is the least 
distinguishing mark of play as contrasted 
with serious function. This question is dis¬ 
cussed from two points of view, the biological 
and the psychological, which illustrate a dis¬ 
tinction in the definition of end or purpose. 
Biologically, we have two main theories : the 
‘surplus energy’theory of Spencer which makes 
play the using up of surplus energy already 
accrued to the organism. Play is then an 
exercise which brings out, generally in an 
imitative way, the functions whose end is 
usually strenuous life under stress of the 
environment. The other theory is the * prac¬ 
tice ' theory, urged strongly by Groos, though 
suggested by earlier writers ; it holds that 
play is a native impulse, not always imitative, 
whose biological end and utility is to secure 
practice in the performance of the essential 
functions of life before they are actually de¬ 
manded by the exigencies of living. A third 
theory—rather more physiological—makes play 
a means to the recuperation of other functions 
during periods in which the functions set in 
play are in exercise. 
On the psychological side, two main char¬ 
acters have been suggested by different writers 
as essential to play. Semblance (q. v.), with 
a certain ‘ self-illusion,’ or indulgence in con¬ 
scious ‘ shamming,’ is to some (v. Hartmann, 
L. Lange) the psychological essential. To 


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