Carl (Edward) Sagan 1934–

American nonfiction writer, scriptwriter, and editor.

Most widely known for his television series "Cosmos," Sagan is Professor of Astronomy and Space Sciences and director of the Laboratory for Planetary Studies at Cornell University. While he has written many articles for scientific journals, Sagan is also concerned that scientific theory be accessible to the general public. Toward this end he has written books for nonscientists, contributed to popular magazines and encyclopedias, and made frequent appearances on television talk shows. Sagan's attempt at writing practical explanations is evident in The Cosmic Connection: An Extraterrestrial Perspective (1973), The Dragons of Eden: A Speculative Essay on the Origin of Human Intelligence (1977), Broca's Brain: Reflections on the Romance of Science (1979), and Cosmos (1981). In these works Sagan presents scientific theories and philosophizes about the effects of scientific inquiry on social, political, religious, and historical events. The Dragons of Eden was awarded the 1977 Pulitzer Prize in nonfiction. Sagan has received several other awards for his work, including two from the National Aeronautics and Space Administration.

Sagan's interests center on the origins and evolution of life on earth, the nature of the physical universe, and the possible existence of extraterrestrial life. Convinced that there is life on other planets, Sagan advocates interplanetary communication; as a consultant to NASA, he helped design the plaque bearing a message to alien life which was launched with the spaceships Pioneers 10 and 11. Using information about the atmosphere on planets in our solar system and elsewhere, Sagan suggests that amid the "billions and billions" of stars and galaxies in the universe, millions of planets may support civilizations like our own. He outlines this probability in The Cosmic Connection, Cosmos, and some of the essays in the collection Broca's Brain. In these works he also emphasizes the importance of space travel. According to Sagan, humans require exploration for their psychological well-being, and since earth has been thoroughly searched, space offers the next frontier. In addition, Sagan believes that contact with extraterrestrials will give humans a wider, less egocentric outlook, an attitude which Sagan refers to as "the cosmic perspective."

In both The Dragons of Eden and Cosmos Sagan recounts the hypothesis of the triune brain, claiming that the human brain is an evolutionary combination of reptilian, prehuman mammalian, and uniquely human aspects. According to Sagan, each of these three parts, which are referred to as the R-complex, the limbic system, and the neocortex, accounts for certain aspects of human behavior: our aversion to reptiles, our base instincts, and our rational thoughts. Sagan also attributes human intelligence to the physical evolution of the brain. From his central arguments, Sagan goes on to speculate about the goals of past civilizations and the effects on future civilizations of potential scientific advances. Many critics conclude that Sagan's underlying message throughout his works, and especially in Cosmos, is that in order to continue evolving intelligently, humans must utilize scientific discovery.

Much controversy surrounds Sagan's theories and his presentation of them. Some critics object to Sagan's glorification of rationality and to his categorical dismissal of a godlike creator. Others find his factual information about evolution and psychology faulty or oversimplified. Many commentators are dissatisfied with Sagan's lack of distinction between assumption and fact, an absence which they judge misleading. The television series "Cosmos" has been criticized for its confusing structure and its emphasis on visual effects rather than argument. Nevertheless, Sagan is praised for his attempt to unite science and philosophy and for his ability to simplify complex concepts while preserving their awesome implications. Many critics consider Sagan's arguments both inspired and logical. With a direct, factual style, a dry wit, and an enthusiasm often described as "contagious," Sagan continues to provide thought-provoking material for scientific and general discussion.

(See also Contemporary Authors, Vols. 25-28, rev. ed.; Contemporary Authors New Revision Series, Vol. 11; and Contemporary Issues Criticism, Vol. 2)