be a way of saying that there ought to be no
slaves; that 'property is theft,' is an uncompromising assertion of the
communistic ideal. Similarly a truism may have rhetorical value: that 'a
Negro is a man' has often been a timely reminder, or even that "a man's
a man." It is only when we fall into such contradiction or tautology by
lapse of thought, by not fully understanding our own words, that it
becomes absurd.

Real Propositions comprise the predication of Propria and Accidentia.
Accidentia, implying a sort of empirical law, can only be established by
direct induction. But propria are deduced from (or rather by means of)
the definition with the help of real propositions, and this is what is
called 'arguing from a Definition.' Thus, if increasing capacity for
co-operation be a specific character of civilisation, 'great wealth' may
be considered as a proprium of civilised as compared with barbarous
nations. For co-operation is made most effectual by the division of
labour, and that this is the chief condition of producing wealth is a
real proposition. Such arguments from definitions concerning concrete
facts and causation require verification by comparing the conclusion
with the facts. The verification of this example is easy, if we do not
let ourselves be misled in estimating the wealth of barbarians by the
ostentatious "pearl and gold" of kings and nobles, where 99 per cent. of
the people live in penury and servitude. The wealth of civilisation is
not only great but diffused, and in its diffusion its greatness must be
estimated.

To argue from a definition may be a process of several degrees of
complexity. The simplest case is the establishing of a proprium as the
direct consequence of some connoted attribute, as in the above example.
If the definition has been correctly abstracted from the particulars,
the particulars have the attributes summarised in the definition; and,
therefore, they have whatever can be shown to follow from those
attributes. But it frequently happens that the argument rests partly on
the qualities connoted by the class name and partly on many other facts.

In Geometry, the proof of a theorem depends not only upon the definition
of the figure or figures directly concerned, but also upon one or more
axioms, and upon propria or constructions already established. Thus, in
Euclid's fifth Proposition, the proof that the angles at the base of an
isosceles triangle are equal, depends not only on the