Even scientific theories build themselves into paradigms, which tend to become dogmatic and resist new approaches as Thomas Kuhn has established. Only when a whole mass of contrary evidence accumulates does the old dam burst. Only when old professors retire or die can new theories rule the day. It is one of the most dangerous and counter-productive traits of human personality. But in the context of politics, relations between social groups, and science, it brings nothing but problems.
Cognitive openness is the opposite of rigidity.
It means being constantly open to new evidence. It means seeking out new evidence. It means actively looking for evidence that might contradict your hypothesis. Successful science seeks the simplest explanation for things - consistent with the evidence. Non sunt multiplicanda entia praeter necessitatem.