Far from being magisterial in its objectivity, science was conditioned by history, society, and the prejudices of scientists.

All crises begin with the blurring of a paradigm and the consequent loosening of the rules for normal research. .. Or finally, the case that will most concern us here, a crisis may end with the emergence of a new candidate for paradigm and with the ensuing battle over its acceptance.

Rather than being an interpreter, the scientist who embraces a new paradigm is like the man wearing inverting lenses.

Concerned to reconstruct past ideas, historians must approach the generation that held them as the anthropologist approaches an alien culture. They must, that is, be prepared at the start to find that natives speak a different language and map experience into different categories from those they themselves bring from home. And they must take as their object the discovery of those categories and the assimilation of the corresponding language.

Political revolutions aim to change political institutions in ways that those institutions themselves prohibit. Their success therefore necessitates the partial relinquishment of one set of institutions in favor of another, and in the interim, society is not fully governed by institutions at all

"Normal science" means research firmly based upon one or more past scientific achievements, achievements that some particular scientific community acknowledges for a time as supplying the foundation for its further practice.

What a man sees depends both upon what he looks at and also upon what his previous visual-conceptual experience has taught him to see.