"On the basis of a knowable universe and of a rational faculty's competence to grasp it, you can define man's proper ethics, politics and esthetics. (And if you make an error, you retain the means and the frame of reference necessary to correct it.) But what will you accomplish if you advocate honesty in ethics, while telling them there is no such thing as truth, fact or reality? What will you do if you advocate political freedom on the grounds that you feel it is good, and find yourself confronting an ambitious thug who declares that he feels quite differently?"

Ayn Rand