The Demon-Haunted World is the last book published during Carl Sagan’s lifetime. (Another book, Billions and Billions was published posthumously.) Most of Sagan’s books concern some aspect of science, particularly astronomy. Demons is more concerned with pseudoscience and scientific education (or the lack thereof).
Sagan describes pseudoscience as ideas that ’’purport to use the methods and ideas of science, while in fact they are faithless to its nature-- often because they are based on insufficient evidence or because they ignore clues that point the other way.’’ Pseudoscience differs from erroneous science. Scientists, after all, are human. They can and do make mistakes, but scientists use a methodology that helps them gradually weed out their errors. Practitioners of pseudoscience, on the other hand, tend to discourage skeptical inquiry.
Sagan devotes the nearly half the book to describing several kinds of pseudoscience. He describes the erroneous science behind them; for example, as per contemporary geology, Atlantis did not exist. He also describes some of the cultural aspects of pseudoscience. One interesting example is the parallels he draws between modern accounts of alien abductions and medieval accounts of demonic attacks. Sagan finds so many similarities between these phenomena that he believes they are the same thing-- but as the cultures changed, so did the descriptions. In both cases, he believes they can be ascribed to dreams or hallucinations.
While some aspects of pseudoscience may sound amusing, Sagan points out that it can do real harm. For example, a man named Trofim Lysenko argued that Mendelian genetics-- for which there was considerable scientific evidence by the 1930’s-- somehow went against the tenets of Marxist communism. He proposed an alternative form of genetics that would be more compatible with communist dialectical materialism. Unfortunately, his alternative genetics involved the inheritance of acquired characteristics-- a concept that has long been disproved. To make matters worse, both Stalin and Khrushchev supported him-- and the Soviet Union fell behind other countries in agricultural techniques and molecular biology. It wasn’t until 1964 that Lysenko’s ideas were finally refuted.
Sagan draws a parallel between Lysenkoism and ’’scientific creationism’’ wherein he points out that Lysenko and his followers censored textbooks to remove all mentions of Mendelian genetics, just as creationists in the United States censor textbooks to remove all mentions of evolution. I should mention here that Sagan classes some religious beliefs, such as creationism, as pseudosciences. Sagan’s attitude toward some religious traditions may therefore strike some readers as offensive.
Sagan believes that the only way to fight pseudoscience is through improved scientific education. He recommends that science courses should include a thorough description of the scientific method itself, and how it works. The scientific method can be quickly described as observation, followed by the formulation of hypotheses, followed by experimentation to prove or disprove the hypotheses. Sagan stresses the importance of understanding the scientific method in particular and critical thinking in general. Indeed, he devotes a chapter, ’’The Fine Art of Baloney Detection’’ to recognizing illogical arguments.
Finally, Sagan believes that scientific education should put less emphasis on rote memorization and more on helping students cultivate both wonder and skepticism. Wonder enables a person to see the grandeur in at least some aspects of science, while skepticism encourages them to ask questions. In Sagan’s view, a poorly taught science class will deaden curiosity rather than awaken it-- and curiosity is at the heart of science.
Sagan was rightly considered one of the top popularizers of science of the late 20th century. He had a gift for describing even the most complicated and arcane concepts in a way that made them comprehensible to laymen. He also had the gift for making his enthusiasm for a topic very plain.