The term "paradigm shift" was coined by the American philosopher Thomas Kuhn (1922-1996). He argued that science couldn't advance until most people working within a field agree upon a paradigm. Before the agreement, collaboration and teamwork are restricted.

Once a paradigm theory is established, those working within it can start doing normal science. But now and then, normal science reveals anomalies that can't be explained within the dominant paradigm. When the inexplicable results start piling up, it eventually leads to a "crisis."

Thomas Kuhn argues that reality cannot be described independently of the conceptual schemes through which we observe it. Paradigm theories explain our conceptual systems.

When a paradigm shift occurs, the theoretical opinions of scientists working in the field changes.

Kuhn's claim related to paradigm shifts is very controversial.

His critics argue that this "non-realist" approach leads to a sort of relativism, and concludes that scientific progress has nothing to do with getting closer to the truth. Kuhn states he still believes in scientific progress since later theories are usually better than earlier theories.