The Demon-Haunted World: Science as a Candle in the Dark

Nonfiction | Book | Adult | Published in 1996

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Summary

Background

Chapter Summaries & Analyses

Preface-Chapter 2

Chapters 3-5

Chapters 6-8

Chapters 9-11

Chapters 12-14

Chapters 15-17

Chapters 18-20

Chapters 21-23

Chapters 24-25

Key Figures

Themes

Index of Terms

Important Quotes

Essay Topics

Tools

Beta

Discussion Questions

Index of Terms

Falsifiability

A term coined by the philosopher of science Karl Popper in his work The Logic of Scientific Discovery (1934), signifying a standard basis of evaluation for scientific theories and hypothesis. A hypothesis is said to be falsifiable (or refutable) if it can be proven true or false by independent research using pre-existing empirical tests. If a proposition is falsifiable, then it can be accepted into scientific study, and other propositions or conclusions can build off of it. If it is not, it likely falls into the realm of non-science or pseudoscience.

Sagan introduces the concept in Chapter 10 with his thought experiment of the dragon in the garage. Since the friend’s claims of an “invisible, incorporeal, floating dragon” (171) cannot be falsified, Sagan cannot accept the existence of the animal. Without concrete evidence, it would be irresponsible to draw further conclusions about the wider existence of dragons. The concept of falsifiability is extremely important to Sagan’s wider argument, as it provides an early example of the type of proactive thinking that he encourages, and is part of his Baloney Detection Kit. Determining which claims are falsifiable is the first step of the skeptical apparatus, allowing scientists and careful thinkers to easily separate dubious claims from those requiring further research.

Pseudoscience

A term emerging from the scientific revolution of the late 18th century, and first applied to the discredited practice of alchemy, pseudoscience consists of statements, beliefs, and practices that claim to be factual and consistent with the values of science, but are in fact incompatible with the scientific method. Common characteristics of pseudoscience are non-falsifiability, unwillingness to submit to outside study or experts, a reliance on confirmation bias, lack of rigor in testing hypotheses, and an unwillingness to alter one’s beliefs in the face of contradictory evidence.

Sagan, as a scientist attempting to teach the scientific method and skeptical thinking, uses case studies and anecdotes to demonstrate that the characteristics of pseudoscience essentially run counter to those of science. Taking a variety of pseudoscientific beliefs in turn, Sagan explains their logical inconsistencies and provides a corrective mode of thinking. Pseudoscience is not just a foil in Sagan’s argument, however. Sagan recognizes the allure of pseudoscientific claims and laments that its false wonders have gripped so many. Not only are they then blinded to the captivating and real wonders of science, which Sagan believes will motivate generations of scientists, but they also weaken the intellectual rigor that Sagan promotes as essential to maintaining a healthy mind and a healthy democratic society.

Scientific Method

While the term has its roots in the early 19th century, the mode of scientific inquiry and skeptical thinking that it characterizes can be traced back to the ancient world. As it is understood today, the scientific method is a form of knowledge building based upon a cyclical process of inductive observation and empirical testing. The scientific method is built upon observations of phenomena, the formation of hypotheses to explain the phenomena, predictive reasoning based upon the hypotheses, and then carefully designed empirical testing to confirm or contradict the hypotheses. From this stage, new observations can be made, and the cycle begins again.

Sagan reveres the scientific method and holds that its rationalistic, empirical underpinnings are the most effective tools humans have for determining the causes behind the natural phenomena of the universe. It is a method free of political or cultural bias that is composed of “built-in error correcting machinery” (31). Results derived from the method can be trusted and confirmed, which allows it to perpetuate knowledge with very little outside hindrance. Sagan finds much promise in the method, and his procedure for skeptical thinking in other realms is heavily based upon the rationalism and empiricism that characterize it. Skepticism relies on the scientific method—as Sagan is quick to point out, skepticism is the activating source that leads many to begin their observations, and go on to employ the scientific method.