The Skeptics' Guide to the Universe: How To Know What's Really Real in a World Increasingly Full of Fake

by Steven Novella

False Analogy A false or faulty analogy consists of assuming that because two or more things are similar in one way, then they are also similar in some other way, ignoring any important distinctions between the two. One might say that the protein complex that moves the flagellum of a bacterium is like a motor. Creationists then argue that this is evidence against evolution, because motors are designed and therefore the flagellum must also have been designed. They are taking a metaphor that was intended to convey one meaning and extending it to another, turning a legitimate analogy into a false analogy. Flagella are like motors in that they have multiple moving parts that work together to create a specific motion. That is where the analogy ends, however. The flagellum is a biological motor, so it has a biological origin. Car motors are not biological; they are inanimate and therefore cannot evolve on their own.