Those who invalidate reason ought seriously to consider whether they argue against reason with or without reason; if with reason, then they establish the principle that they are laboring to dethrone: but if they argue without reason (which, in order to be consistent with themselves they must do), they are out of reach of rational conviction, nor do they deserve a rational argument.

— The Demon-Haunted World by Carl Sagan, Ann Druyan (Page 251)