predicates analyse the whole connotations of their subjects, are
indispensable instruments of science (see chap. xxii.).

Of course, hypothetical propositions may also be verbal, as _If the soul
be material it is extended_; for 'extension' is connoted by 'matter';
and, therefore, the corresponding disjunctive is verbal--_Either the
soul is not material, or it is extended_. But a true divisional
disjunctive can never be verbal (chap. xxi. § 4, rule 1).

On the other hand, when there is no such direct relation between subject
and predicate that their connotations imply one another, but the
predicate connotes something that cannot be learnt from the connotation
of the subject, there is no longer tautology, but an enlargement of
meaning--e.g., _Masters are degraded by their slaves; The horse is the
noblest animal; Red is the favourite colour of the British army; If the
soul is simple, it is indestructible_. Such propositions are called
Real, Synthetic, or Ampliative, because they are propositions for which
a mere understanding of their subjects would be no substitute, since the
predicate adds a meaning of its own concerning matter of fact.

To any one who understands the language, a verbal proposition can never
be an inference or conclusion from evidence; nor can a verbal
proposition ever furnish grounds for an inference, except as to the
meaning of words. The subject of real and verbal propositions will
inevitably recur in the chapters on Definition; but tautologies are such
common blemishes in composition, and such frequent pitfalls in argument,
that attention cannot be drawn to them too early or too often.