Which theory was a justification for European imperalism?

One of the key theories that justified European Imperialism was Social Darwinism. This ideology applied the concept of "survival of the fittest" to human societies, suggesting that stronger nations had the right and duty to dominate weaker ones. Proponents believed that colonial expansion was a natural and beneficial process, promoting civilization and progress among supposedly "lesser" cultures. This notion was often used to rationalize the exploitation and subjugation of various peoples across the globe.