Cliffs Quote by Clayton Christensen

“I am using the word theory as a scientist means it: a set of ideas so well established by observations and physical models that…

— Philip C. Plait

To construct a scientific theory from the data and to be able to recognize that it is a reasonable theory is possible only if…

— Noam Chomsky

There is nothing more practical than a good theory.

— Leonid Brezhnev

Nothing is more practical than a good theory.

— Ludwig Boltzmann

There is nothing so practical as a good theory.

— Kurt Lewin

[Theory is] an explanation that has been confirmed to such a degree, by observation and experiment, that knowledgeable experts accept it as fact. That's…

— David Quammen

A theory is scientific only if it can be disproved. But the moment you try to cover absolutely everything the chances are that you…

— Hermann Bondi

Theories, for me, are just about freeing your mind. It doesn't mean the theory is going to work like a scientific theory works. It's…

— Steve Martin

A theory is a good theory if it satisfies two requirements: it must accurately describe a large class of observations on the basis of…

— Stephen Hawking

There can be theory but, you know, the problem is you've got to be able to test it. So theories are one thing, testing…

— Brian Schmidt

Theory is knowledge that doesn't work. Practice is when everything works and you don't know why.

— Hermann Hesse

As you know, a theory in physics is not useful unless it is able to predict underlined effects which we would otherwise expect.

— Richard P. Feynman