Asklemmy

Historical materialism perfectly answers your question. Quote from On Dialectical and Historical Materialism by J.V. Stalin:

"It is easy to understand how immensely important is the extension of the principles of the dialectical method to the study of social life and the history of society, and how immensely important is the application of these principles to the history of society and to the practical activities of the party of the proletariat.

If there are no isolated phenomena in the world, if all phenomena are interconnected and interdependent, then it is clear that every social system and every social movement in history must be evaluated not from the standpoint of "eternal justice" or some other preconceived idea, as is not infrequently done by historians, but from the standpoint of the conditions which gave rise to that system or that social movement and with which they are connected.

The slave system would be senseless, stupid and unnatural under modern conditions. But under the conditions of a disintegrating primitive communal system, the slave system is a quite understandable and natural phenomenon, since it represents an advance on the primitive communal system

The demand for a bourgeois-democratic republic when tsardom and bourgeois society existed, as, let us say, in Russia in 1905, was a quite understandable, proper and revolutionary demand; for at that time a bourgeois republic would have meant a step forward. But now, under the conditions of the U.S.S.R., the demand for a bourgeois-democratic republic would be a senseless and counterrevolutionary demand; for a bourgeois republic would be a retrograde step compared with the Soviet republic.

Everything depends on the conditions, time and place.

It is clear that without such a historical approach to social phenomena, the existence and development of the science of history is impossible; for only such an approach saves the science of history from becoming a jumble of accidents and an agglomeration of most absurd mistakes"