On the freedom to doubt................

     This freedom to doubt is an important matter in the sciences and, I believe, in other fields.  It was born of a struggle.  It was a struggle to be permitted to doubt, to be unsure.  And I do not want us to forget the importance of the struggle and, by default, to let the thing fall away.  I feel a responsibility as a scientist who knows the great value of a satisfactory philosophy of ignorance, and the progress made possible by such a philosophy, progress which is the fruit of freedom of thought.  I feel a responsibility to proclaim the value of this freedom and to teach that doubt is not to be feared, but that it is to be welcomed as the possibility of a new potential for human beings.  If you know that you are not sure, you have a chance to improve the situation.  I want to demand this freedom for future generations.

-Richard P. Feynman,  The Meaning of It All:  Thoughts of a Citizen-Scientist