A population explosion will affect the need man has to change his environment by affecting the life of the road surfaces, the speed at which houses degenerate into slums and many other matters.
Adaptation to these needs may lead to changes in the methods of production and distribution, leading to further changes in the physical environment, with additional effects on the economic and other social arrangements and leading to the formulation of new ideas about what social organisation is or ought to be.
All these factors give rise to political change, for the process by which public policy is arrived at, and the policy itself, is essentially affected by physical and social alterations and politicians, political institutions and political ideas interact on the world around them.
As with other types of change, the political may differ in extent, direction and speed. All these notions must be taken care of while considering distinctions between reform and revolution.