Carl Sagan - "A Demon Haunted World"

The Demon-Haunted World: Science as a Candle in the Dark is a book by astrophysicist Carl Sagan, which was first published in 1995.

The book is intended to explain the scientific method to laymen, and to encourage people to learn critical or skeptical thinking. It explains methods to help distinguish between ideas that are considered valid science, and ideas that can be considered pseudoscience. Sagan states that when new ideas are offered for consideration, they should be tested by means of skeptical thinking, and should stand up to rigorous questioning.

In the book, Sagan states that if a new idea continues in existence after an examination of the propositions, it should then be acknowledged as a supposition. Skeptical thinking essentially is a means to construct, understand, reason, and recognize valid and invalid arguments. Wherever possible, there must be independent validation of the concepts whose truth should be proved. He believes that reason and logic would succeed once the truth is known. Conclusions emerge from premises, and the acceptability of the premises should not be discounted or accepted because of bias.

As an example, Sagan relates the story of the invisible fire-breathing dragon living in his garage. He asks, "what's the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all? If there's no way to disprove my contention, no conceivable experiment that would count against it, what does it mean to say that my dragon exists? Your inability to invalidate my hypothesis is not at all the same thing as proving it true."

Sagan presents a set of tools for skeptical thinking which he calls the "baloney detection kit". Skeptical thinking consists both of constructing a reasoned argument and recognizing a fallacious or fraudulent one. In order to identify a fallacious argument, Sagan suggests the employment of such tools as independent confirmation of facts, quantification and the use of Occam's razor. Sagan's "baloney detection kit" also provides tools for detecting "the most common fallacies of logic and rhetoric", such as argument from authority and statistics of small numbers. Through these tools, Sagan argues the benefits of a critical mind and the self-correcting nature of science can take place.

Sagan provides a skeptical analysis of several kinds of superstition, fraud, pseudoscience and religious beliefs, such as gods, witches, UFOs, ESP and faith healing. However, based on what he describes as "some, although still dubious experimental support," Sagan calls for serious scrutiny of a handful of seemingly inexplicable phenomena such as reincarnation and psychokinesis, not because he regards them as likely to be true, but because anomalous data deserves close scientific study.