Even the most stubborn are usually solved by normal science . He says that everything that can be seen as a counterinstance to a theory can also be seen as a puzzle of that theory . Indeed, much of scientific progress is in solving those puzzles . He says that once a paradigm is established, there is no such thing as research in the absence of a paradigm . And there is no such thing as rejection of a paradigm without another to take its place . .
Normal science goes astray when it goes into crisis, when an anomaly is more than an anomaly .
Kuhn talks about instances that make anomalies particularly pressing and notes that it usually takes several of these instances to provoke crisis . The anomalies become more recognized by the profession . The anomaly may exist on a key point of the theory and thus be recognized instantly . Anomalies build up . Crises are necessary for the emergence of new theories .