The Demon-Haunted World

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The Demon-Haunted World: Science as a Candle in the Dark
The Demon-Haunted World, first edition cover.jpg
Cover of the first edition
AuthorCarl Sagan
CountryUnited States
SubjectsScientific skepticism
PublisherRandom House
Publication date
Media typePrint (hardcover and paperback)
001.9 20
LC ClassQ175 .S215 1995
Preceded byPale Blue Dot 
Followed byBillions and Billions 

The Demon-Haunted World: Science as a Candle in the Dark is a 1995 book by the astrophysicist Carl Sagan, in which the author aims to explain the scientific method to laypeople and to encourage people to learn critical and skeptical thinking. He explains methods to help distinguish between ideas that are considered valid science and those 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.


Sagan explains that science is not just a body of knowledge, but is a way of thinking. Sagan shows how scientific thinking is both imaginative and disciplined, bringing humans to an understanding of how the universe is, rather than how they wish to perceive it. He says that science works much better than any other system because it has a "built-in error-correcting machine".[1]:27 Superstition and pseudoscience get in the way of the ability of many laypersons to appreciate the beauty and benefits of science. Skeptical thinking allows people 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 states that reason and logic would succeed once the truth were known. Conclusions emerge from premises, and the acceptability of the premises should not be discounted or accepted because of bias.

Dragon in my garage[edit]

As an example of skeptical thinking, Sagan offers a story concerning a fire-breathing dragon who lives in his garage. When he persuades a rational, open-minded visitor to meet the dragon, the visitor remarks that they are unable to see the creature. Sagan replies that he "neglected to mention that she's an invisible dragon". The visitor suggests spreading flour on the floor so that the creature's footprints might be seen, which Sagan says is a good idea, "but this dragon floats in the air". When the visitor considers using an infrared camera to view the creature's invisible fire, Sagan explains that her fire is heatless. He continues to counter every proposed physical test with a reason why the test will not work.

Sagan concludes by asking: "Now 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."

Continuing with concepts relevant to the 'dragon in my garage' story, Sagan writes about a patient of John Mack who claimed to have scars on her body which were from encounters with aliens. Sagan writes that if the patient is asked what her scars look like, she is unable to show them because, unfortunately, they are located in the private areas of her body.

Baloney detection kit[edit]

Sagan presents a set of tools for skeptical thinking that he calls the "baloney detection kit".[2][3]:210[4] 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 employing such tools as independent confirmation of facts, debate, development of different hypotheses, quantification, the use of Occam's razor, and the possibility of falsification. 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.

There are a total of nine tools in this kit. The first of these tools that Sagan provides is that there must be confirmation of the facts given when possible. The next tool in the "baloney detection kit" is to encourage debate on the evidence from all points of view. The next tool is that we must realize that an argument from authority is not always reliable. Sagan supports this by telling us that 'authorities" have made mistakes in the past and they will again in the future. The fourth tool in the kit is to consider more than one hypothesis. Sagan adds to this by telling us that we must think of the argument from all angles and think all the ways it can be explained or disproved. The hypothesis that then still hasn't been disproved has a much higher chance of being correct. The fifth tool in the kit is to try your best to not purely stick to a hypothesis that is your own and become bias. Sagan tells us to compare our own hypothesis with others to see if we can find reasons to reject our own hypothesis. The next tool in the kit is to quantify. Sagan tells us that if whatever we are trying to explain has numerical value or quantitative data related to it, then we'll be much more able to compete against other hypotheses. The next tool is that we must know that if there is a chain of argument, every link in that chain must be correct. The eighth and possibly most important tool in the "baloney detection kit" is the use of Occam's razor, which tells us to choose the hypothesis that is simpler and requires the least amount of assumptions. The final tool in the kit is to always ask if a given hypothesis can be falsified. Sagan tells us that if a hypothesis cannot be tested or falsified then it is not worth considering. With the use of this "baloney detection kit" it is easier to critically think and find the truth.

There is a second part to the kit that Sagan gives us. This consists of twenty different logical fallacies that one must not commit when offering up a new claim. The first of these fallacies is ad hominem which is when an arguer attacks the opposing arguer and not the actual argument. Next is the argument from authority which is when someone expects another to immediately believe that a person of authority or higher knowledge is correct. The third fallacy that Sagan gives us is the argument from adverse consequences. This is when someone says that something must be done a certain way or else there will be adverse consequences. The next fallacy is the appeal to ignorance. This is when one argues a claim in that whatever has not been proved false must be true, and vice versa. Next Sagan tells us not to commit special pleading. This is when an arguer responds to a deeply complex or rhetorical question or statement by, usually, saying "oh you don't understand how so and so works". The next fallacy is known as begging the question. This is when an arguer assumes the answer and makes a claim such as, this happened because of that, or, this needs to happen in order for that to happen. The next fallacy Sagan gives us is called observational selection. This is when someone talks about how great something is by explaining all of the positive aspects of it while purposely not mentioning any of the negative aspects. The next fallacy, as Sagan calls it, is statistics of small numbers. This is when someone argues something by giving the statistics in small numbers, which isn't very reliable. Next is the fallacy called misunderstanding of the nature of statistics. This is when, as you would assume, someone misinterprets statistics given to them. Next is the fallacy of inconsistency. This is when, as you would also assume, an arguer is very inconsistent in their claims. The next fallacy is non sequitur. This is Latin for "it doesn't follow". This fallacy is committed when a claim is made that doesn't make much sense, such as "Our nation will prevail because God is great". The next fallacy Sagan discusses is called post hoc ergo propter hoc, Latin for "it happened after, so it was caused by." This fallacy is committed when an arguer claims that something happened because of a past event when really it probably didn't. The next fallacy is known as a meaningless question. This fallacy is committed when someone asks a question that has no real meaning or doesn't add to the argument at all. Sagan also discusses a fallacy known as the excluded middle. This fallacy is committed when an arguer only considers or mentions the two opposite extremes of the conversation and excludes the aspects in between the two extremes.

Sagan provides a skeptical analysis of several examples of what he refers to as superstition, fraud, and pseudoscience such as witches, UFOs, ESP, and faith healing. He is critical of organized religion.[citation needed]

In a 2020 interview for Skeptical Inquirer, when Sagan's wife Ann Druyan was asked about the origin of the phrase "baloney detection kit", she said that

It didn’t really come from Carl. It actually came from a friend of mine named Arthur Felberbaum who died about forty years ago. He and Carl and I once sat down for dinner together. His politics were very left wing, so Carl and Arthur and I were trying to find common ground so that we could have a really good dinner together. And at one point, Arthur said, “Carl, it’s just that I dream that every one of us would have a baloney detection kit in our head.” And that’s where that idea came from.[2]

Misuse of science[edit]

Sagan indicates that science can be misused. Thus, he is highly critical of Edward Teller, the "father of the hydrogen bomb", and Teller's influence on politics, and contrasts his stance to that of Linus Pauling and other scientists who took moral positions.[citation needed]

Sagan also discusses the misuse of science in representation. He relates to the depiction of the mad scientist character in children's TV shows and is critical of this occurrence. Sagan suggests an addition of scientific television programs, many of which would take a look at believed hoaxes of the past and encourage viewers to engage in critical thinking to better represent science on popular television.

Misuse of psychiatric authority[edit]

Sagan indicates that therapists can contribute to the growth of pseudoscience or the infusion of "false stories". He is critical of John Mack and his support of alien abduction cases, which were represented in his patients.

Sagan writes about the story of Paul Ingram. Ingram's daughter reported that her father had sexually abused her. He was told that "sex offenders often repressed memories of their crimes."[5] Ingram was eventually able to have a foggy visualization of the claimed events, and he suggested that perhaps "a demon might be responsible."[5] Sagan describes how once Ingram started remembering events, so did several other individuals and family members. A "memory recovery" technique was performed on Ingram, and he confessed to the crimes. A medical examination was done on his daughter, where none of the scars she described were actually found. Sagan writes that Ingram later tried to plead innocence once "away from his daughters, his police colleagues, and his pastor."[5]

Reception and legacy[edit]

The book was a New York Times bestseller.[6] It is considered to be a very important book by the contemporary skeptical movement.[7][8][9][10] The Demon-Haunted World has been criticized for not incorporating certain pieces of information relevant to the items he discusses in his book by Smithsonian magazine and an archived article by The New York Times. In the magazine, it is argued that Sagan relates to issues of government choices and declining scientific thinking skills to pseudoscience topics like astrology and faith healing; but he ignores other issues which may be causing governmental bodies and other individuals to turn away from science. One of these other problems relates to consequences of pouring governmental money into cancer research. Trachtman writes, "it is not because of such beliefs that Congress now approaches the NIH budget with an ax. In fact, billions of dollars spent on years of research in the war on cancer have spawned growing professional bureaucracies and diminishing medical benefits."[11] Trachtman argues that Sagan does not include problems like growing bureaucracies and diminishing medical benefits as reasons for a lack of scientific attention. Also arguing for an unaddressed issue in the book, The New York Times article writes that Sagan fails to emphasize the idea that scientists should take a more active role in reaching science to the public, while he does mention the failures of the education system to do so.[12]

The review in the Smithsonian magazine and a review by the New York Review of Books pull different opinions on Sagan's attitude towards religious ideas. The New York review writes that " when it comes to the Supreme Extraterrestrial he is rather circumspect."[13] An article by the University of Phoenix also agrees that Sagan carefully approaches the concept of religion. The article writes, "Readers should be aware that Sagan touches on sensitive areas in the cultural sphere, such as religion and where it stands in science, but handles the topics in such a way as to not offend."[14] The Smithsonian article suggests that Sagan was very clear about his religious beliefs in the book for he "splits his universe in two, into science and irrationality." The Smithsonian goes on to say that Sagan's defined religious views fall within the area of an untestable claim, a type of claim he argues against in The Demon-Haunted World.[11]

The article by the New York Review also claims that Sagan includes something in The Demon-Haunted World which he also is arguing against in that same text. The article mentions how Sagan discusses a natural predisposition people have towards science. However, the article also writes, "He does not tell us how he used the scientific method to discover the "embedded" human proclivity for science."[13] Sagan heavily discusses the importance of using the scientific method in his book, and this article claims he strays away from his own message by not including a description of his use of the scientific method on this topic.

An article by the Los Angeles Times and a review through the University of Phoenix both describe Sagan's book positively. The Los Angeles Times describes Sagan's book as "a manifesto for clear thought", with the main issue being the length of eight chapters.[15] This length discussion is also addressed in the archived New York Times article,[16] as well as the article through the University of Phoenix which relates to the book as having areas which repeat themselves.[17] The latter article agrees with the use of The Demon-Haunted World as a text to provide tools for clearer thinking. The article writes, "Sagan writes in an engaging style, using dry wit and humor, to get his point across regarding the need for everyone to practice aspects of scientific thinking in their daily lives."[18] This article also discusses the ability of The Demon-Haunted World to help beginner researchers and students learn about the importance of critical thinking early on.[18]

The Demon-Haunted World has been defined in more current sources as something which is still relevant. An article written through The Guardian from 2012, suggests the still current relevance of The Demon-Haunted World.[19] Another article from The Verge in 2017 also supports this relevance.[20] The latter article writes about a disconnect between what is proven by science to be the best answer and what is chosen to be done by governmental bodies.[21] Carl Sagan covers this concept as a prominent issue in his book written in 1995, and this article outlines it as a problem which is still occurring at the time the article was written.

See also[edit]


  1. ^ Sagan, Carl (1997). The Demon-Haunted World: Science As a Candle in the Dark (Reprint ed.). Ballantine Books. ISBN 978-0345409461.
  2. ^ a b Palmer, Rob (31 March 2020). "Exploring 'Possible Worlds' With Ann Druyan". CFI. Archived from the original on 1 April 2020. Retrieved 17 April 2020.
  3. ^ Sagan, Carl (March 1997). The Demon-Haunted World: Science As a Candle in the Dark (Paperback ed.). Ballantine Books. ISBN 978-0-345-40946-1.
  4. ^ Sagan, Carl (1995). The Demon-Haunted World: Science As a Candle in the Dark (Hardback ed.). Random House. ISBN 978-0-394-53512-8.
  5. ^ a b c Sagan, Carl (1997). The Demon-Haunted World: Science As a Candle in the Dark (Reprint ed.). Ballantine Books. ISBN 978-0345409461.
  6. ^ "BEST SELLERS: June 16, 1996". The New York Times. 16 June 1996. Retrieved 17 February 2017.
  7. ^ Bernstein, Evan (November 9, 2015). "Happy Carl Sagan Day!". The Skeptics' Guide to the Universe. Retrieved 17 February 2017.
  8. ^ Novella, Steven. "NeuroLogica Blog » Carl Sagan Day". New England Skeptical Society. Retrieved 17 February 2017.
  9. ^ Meadon, Michael (8 October 2009). "Books IV". Retrieved 17 February 2017.
  10. ^ Swiss, Jamy Ian (9 May 2013). "I, Skeptic". Northeast Conference on Science and Skepticism. Retrieved 17 February 2017 – via YouTube.
  11. ^ a b Trachtman, Paul. “Review of 'The Demon-Haunted World', 'Einstein, History, and Other Passions', 'The End of Science'.”, Smithsonian Institution, 1 May 1997,
  12. ^ The New York Times, The New York Times,
  13. ^ a b Lewontin, Richard C. “Billions and Billions of Demons.” The New York Review of Books, 27 Aug. 2020,
  14. ^ “Book Review: Demon-Haunted World by Carl Sagan.” Book Review: Demon-Haunted World by Carl Sagan | University of Phoenix Research Hub,
  15. ^ “BOOK REVIEW / NON FICTION : For This Scientist, the Truth Is Out There : THE DEMON-HAUNTED WORLD: Science as a Candle in the Dark by Carl Sagan; Random House $25, 452 Pages.” Los Angeles Times, Los Angeles Times, 18 Apr. 1996,
  16. ^ The New York Times, The New York Times,
  17. ^ “Book Review: Demon-Haunted World by Carl Sagan.” Book Review: Demon-Haunted World by Carl Sagan | University of Phoenix Research Hub,
  18. ^ a b “Book Review: Demon-Haunted World by Carl Sagan.” Book Review: Demon-Haunted World by Carl Sagan | University of Phoenix Research Hub,
  19. ^ “The Demon-Haunted World by Carl Sagan – Review | Tim Radford.” The Guardian, Guardian News and Media, 20 July 2012,
  20. ^ Savov, Vlad. “The World Needs Carl Sagan Now More than Ever.” The Verge, The Verge, 24 Jan. 2017,
  21. ^ Savov, Vlad. “The World Needs Carl Sagan Now More than Ever.” The Verge, The Verge, 24 Jan. 2017,

Further reading[edit]