Literally As Well As Metaphorically,

To Turn Karl [popper]'s View On Its Head, It Is Precisely The Abandonment Of Critical Discourse That Marks The Transition Of Science. Once A Field Has Made The Transition, Critical Discourse Recurs Only At Moments Of Crisis When The Bases Of The Field Are Again In Jeopardy. Only When They Must Choose Between Competing Theories Do Scientists Behave Like Philosophers.

We May... Have To Relinquish The Notion, Explicit Or Implicit, That Changes Of Paradigm Carry Scientists And Those Who Learn From Them Closer And Closer To The Truth... The Developmental Process Described In This Essay Has Been A Process Of Evolution From Primitive Beginnings-a Process Whose Successive Stages Are Characterized By An Increasingly Detailed And Refined Understanding Of Nature. But Nothing That Has Been Or Will Be Said Makes It A Process Of Evolution Toward Anything.

Under Normal Conditions The Research Scientist Is Not An Innovator But A Solver Of Puzzles, And The Puzzles Upon Which He Concentrates Are Just Those Which He Believes Can Be Both Stated And Solved Within The Existing Scientific Tradition.

The Resolution Of Revolutions Is Selection By Conflict Within The Scientific Community Of The Fittest Way To Practice Future Science. The Net Result Of A Sequence Of Such Revolutionary Selections, Separated By Periods Of Normal Research, Is The Wonderfully Adapted Set Of Instruments We Call Modern Scientific Knowledge.

In Science Novelty Emerges Only With Difficulty, Manifested By Resistance, Against A Background Provided By Expectation.