The opinion which is fated to be ultimately agreed to by all who investigate, is what we mean by the truth, and the object represented in this opinion is the real.

Consider what effects, that might conceivably have practical bearings, we conceive the object of our conception to have. Then, our conception of these effects is the whole of our conception of the object.

Logic is rooted in the social principle.

Mathematics is the alphabet in which God has written the universe.

-- Galileo Galilei

Observation always involves theory.

-- Edwin Hubble

A theory which is not refutable by any conceivable event is non-scientific.

-- Karl Popper

Philosophy of science is philosophy enough.

-- Willard Van Orman Quine

It is the nature of intelligence to outrun previous formulations of itself.

-- Hilary Putnam

Whoever, in the pursuit of science, seeks after immediate practical utility may rest assured that he seeks in vain.

-- Hermann von Helmholtz