In sociology and biology, conflict theory states that the society or organization functions so that each individual participant and its groups struggle to maximize their benefits, which inevitably contributes to social changes such as revolutions and changes in politics. The theory is mostly applied to explain conflict between social classes in ideologies such as socialism and communism. The theory refutes functionalism, which considers that societies and organization function so that each individual and group plays a specific role, like organs in the body.

In understanding conflict theory, competition plays a key part.

The following are three primary assumptions of modern conflict theory:

1. Competition. Competition over scarce resources (money, leisure, sexual partners, and so on) is at the heart of all social relationships. Competition rather than consensus is characteristic of human relationships.
2. Structural inequality. Inequalities in power and reward are built into all social structures. Individuals and groups that benefit from any particular structure strive to see it maintained.
3. Revolution. Change occurs as a result of conflict between competing interests rather than through adaptation. It is often abrupt and revolutionary rather than evolutionary.