The paradigm guides the activities of scientists Methods are well-defined. Problems are well-defined. Students are indoctrinated. Textbooks specify the rules of the game. Granting agencies reward mainstream science.
Universities hire mainstream scientists.
One theory comes to dominate and becomes the paradigm. Students are trained with the paradigm. Failure to explain something does not disprove the theory, rather it means that more work needs to be done. Some phenomena persistently refuse to act in accordance with the current paradigm - these are anomalies that must now be explained. Attempts to explain the anomalies produce new, more widely divergent theories, causing conflict and crisis.