The Demon-Haunted World: Science as a Candle in the Dark (Carl Sagan 1995) was the Humanist Book Club selection for August 2012. Carl Sagan was a physicist and beloved science populizer. His book is a passionate case for the awe of understanding over the mystery of ignorance. Early on Sagan invokes Hippocrates of Cos, author of the Hippocratic Oath, to make the case.
Hippocrates wrote: "Men think epilepsy divine, merely because they don't understand it. But if they called everything divine that they don't understand, why, there would be no end of divine things." Instead of acknowledging that in many areas we are ignorant, we have tended to say things like the Universe is permeated with the ineffable.
Sagan's book is a bulwark against credulity. It challenges the axiom that ignorance is bliss. Sagan cites a counterargument from Edmund Way Teale's (1950) book, Circle of the Seasons.
It is morally as bad not to care whether a thing is true or not, so long as it makes you feel good, as it is not to care about how you got your money as long as you have got it.
Making the case in his own words, Sagan provides the following popular quote from the book.
For me, it is far better to grasp the Universe as it is than to persist in delusion, however satisfying and reassuring.
One of the dominant themes in the book is the delineation between science and pseudoscience. Sagan explains the importance of this distinction as follows.
If we resolutely refuse to acknowledge where we are liable to to fall into error, then we can confidently expect that error--even serious error, profound mistakes--will be our companion forever. But if we are capable of a little courageous self-assessment, whatever rueful reflections they may engender, our chances improve enormously.
The method of science, as stodgy and grumpy as it may seem, is far more important than the findings of science.
When we are self-indulgent and uncritical, when we confuse hopes and facts, we slide into pseudoscience and superstition.
Where postmodernists tend to take the provisional nature of scientific claim as support for relativism, Sagan explain scientific progress in terms of incremental approximations of the truth. He illustrates using the distinction between Newtonian mechanics and Einstein's theory of General Relativity, and then contrasts science with religion.
This is one of the reasons that the organized religions do not inspire me with confidence. Which leaders of the major faiths acknowledge that their beliefs might be incomplete or erroneous and establish institutes to uncover possible doctrinal deficiencies?
On the importance of rationality, Sagan cites Kenneth V. Lanning, Supervisory Special Agent at the Behavioral Science Instruction and Research Unit of the FBI Academy in Quantico, Virginia who wrote the following in the October 1989 issue of The Police Chief.
Christianity may be good and Satanism evil. Under the Constitution, however, both are neutral. This is an important, but difficult, concept for many law enforcement officers to accept. They are paid to uphold the penal code, not the Ten Commandments ... The fact is that far more crime and child abuse has been committed by zealots in the name of God, Jesus and Mohammed than has ever been committed in the name of Satan. Many people don't like that statement, but few can argue with it.
Claims that cannot be tested, assertions immune to disproof are veridically worthless value they may have for inspiring us or in exciting our sense of wonder.