ARGUMENTS FOR EVOLUTION 149

any special evidences of evolution ; any set of facts in
regard to organisms well worked-out illustrates the
general thesis. At the same time, it is possible to
classify the different ways in which the Evolution-
Idea fits the facts, and this is what Spencer did in
his presentation of the " arguments for evolution"
—a presentation which has never been surpassed
in clearness, though every illustration has been
multiplied many times since 1866.

I. The Arguments from Classification. Spencer
started with the fact that naturalists have utilised
resemblances in structure and development as a basis
for the orderly classification of organisms in groups
within groups—varieties, species, genera, families,
races, and so on. But " this is the arrangement
which we see arises by descent, alike in individual
families and among races of men." " Where it is
known to take place evolution actually produces these
feebly-distinguished small groups and these strongly-
distinguished great groups." " The impression
made by these two parallelisms, which add meaning
to each other, is deepened by the third parallelism,
which enforces the meaning of both—the parallelism,
namely, that as, between the species, genera, orders,
classes, etc., which naturalists have formed, there are
transitional types; so between the groups, sub-
groups, and sub-sub-groups, which we know to have
been evolved, types of intermediate values exist.
And these three correspondences between the known
results of evolution (as in human races, domesticated
animals, and cultivated plants) and the results here
ascribed to evolution have further weight given to
them by the fact, that the kinship of groups throughrel mixture of scientific and trans-s intrinsic incoherence; worthless as