I must begin with a good body of facts and not from a principle (in which I always suspect some fallacy) and then as much deduction as you please.

-Darwin, Charles Robert
  Letter to  J Fiske, 8 Dec.

The grand aim of all science is to cover the greatest number of empirical facts by logical deduction from the smallest number of hypotheses or axioms.

-Einstein, Albert
  Quoted in Life Magazine, 9  Jan.

It is not a correct deduction from the Principles of Economics that enlightened self-interest always operates in the public interest† Experience does not show that individuals when they make up a social unit are always less clear-sighted than when they act separately.

-Keynes (of Tilton),John Maynard, 1st Baron
Essays in Persuasion.