Peter Godfrey-Smith, the author of “Theory and Reality: An Introduction to the Philosophy of Science,” has been thinking about how people can avoid the misunderstanding embedded in the phrase, “It’s only a theory.”
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It’s helpful, he argues, to think about theories as being like maps.“To say something is a map is not to say it’s a hunch,” said Dr. Godfrey-Smith, a professor at the City University of New York and the University of Sydney. “It’s an attempt to represent some territory.”A theory, likewise, represents a territory of science. Instead of rivers, hills, and towns, the pieces of the territory are facts.“To call something a map is not to say anything about how good it is,” Dr. Godfrey-Smith added. “There are fantastically good maps where there’s not a shred of doubt about their accuracy. And there are maps that are speculative.”To judge a map’s quality, we can see how well it guides us through its territory. In a similar way, scientists test out new theories against evidence. Just as many maps have proven to be unreliable, many theories have been cast aside.But other theories have become the foundation of modern science, such as the theory of evolution, the general theory of relativity, the theory of plate tectonics, the theory that the sun is at the center of the solar system, and the germ theory of disease.“To the best of our ability, we’ve tested them, and they’ve held up,” said Dr. Miller. “And that’s why we’ve held on to these things.”
