Progressive Problem Shifts:

"I never had any illusions that the new ideas I was putting forward, and the new theories I was elaborating, would be ‘correct’ even in the rather limited sense which philosophy allows to apply to scientific theories. They were usually, if not always, in the right direction, part of what Imre Lakatos, a well-known philosopher of science, called ‘a progressive problem shift’, as opposed to a ‘degenerative problem shift’, i.e., programmes of research that advance knowledge, rather than programmes of research that fight a rear-guard action by ad hoc explanations of anomalies which proved destructive to the programme."

Hans J. Eysenck