All 3 Uses of

postulate
in
War and Peace

But to arrive at these laws, resulting from the sum of all those human wills, man's mind postulates arbitrary and disconnected units.†
Chpt 11 *

Instead of the former divinely appointed aims of the Jewish, Greek, or Roman nations, which ancient historians regarded as representing the progress of humanity, modern history has postulated its own aims—the welfare of the French, German, or English people, or, in its highest abstraction, the welfare and civilization of humanity in general, by which is usually meant that of the peoples occupying a small northwesterly portion of a large continent.†
Chpt 15

Postulating some generalization as the goal of the movement of humanity, the historians study the men of whom the greatest number of monuments have remained: kings, ministers, generals, authors, reformers, popes, and journalists, to the extent to which in their opinion these persons have promoted or hindered that abstraction.†
Chpt 15

Definition:

something assumed as a basis for further logical development; or the proposal of such an assumption