All Crises Begin With The Blurring Of

Individuals Who Break Through By Inventing A New Paradigm Are Almost Always Either Very Young Men Or Very New To The Field Whose Paradigm They Change. These Are The Men Who, Being Little Committed By Prior Practice To The Traditional Rules Of Normal Science, Are Particularly Likely To See That Those Rules No Longer Define A Playable Game And Conceive Another Set That Can Replace Them.

As In Political Revolutions, So In Paradigm Choice-there Is No Standard Higher Than The Assent Of The Relevant Community... This Issue Of Paradigm Choice Can Never Be Unequivocally Settled By Logic And Experiment Alone.

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

The Historian Of Science May Be Tempted To Exclaim That When Paradigms Change, The World Itself Changes With Them.

Though The World Does Not Change With A Change Of Paradigm, The Scientist Afterward Works In A Different World... I Am Convinced That We Must Learn To Make Sense Of Statements That At Least Resemble These. What Occurs During A Scientific Revolution Is Not Fully Reducible To A Re-interpretation Of Individual And Stable Data. In The First Place, The Data Are Not Unequivocally Stable.