This search has hitherto been unsuccessful, and the analogy of the biological sciences suggests that politicians are most likely to acquire the power of valid reasoning when they, like doctors, avoid the over-simplification of their material, and aim at using in their reasoning as many facts as possible about the human type, its individual variations, and its environment.

Biologists have shown that large numbers of facts as to individual variations within any type can be remembered if they are arranged as continuous curves rather than as uniform rules or arbitrary exceptions.

On the other hand, any attempt to arrange the facts of environment with the same approach to continuity as is possible with the facts of human nature is likely to result in error.

The study of history cannot be assimilated to that of biology.
_( Chapter V .-- The Method of Political Reasoning, page 138)_ The method of political reasoning has shared the traditional over-simplification of its subject-matter.
In Economics, where both method and subject-matter were originally still more completely simplified, 'quantitative' methods have since Jevons's time tended to take the place of 'qualitative'.

How far is a similar change possible in politics?
Some political questions can obviously be argued quantitatively.