15.2: Reviewing the Principles of Scientific Reasoning

One fairly significant aspect of scientific reasoning distinguishes it from other reasoning: Its justification process can be more intricate. For example, you and I might look back over our experience of gorillas, seeing them in zoos and seeing pictures of them in books, and draw the conclusion that all gorillas are black. A biological scientist interested in making a statement about gorilla color would not be so quick to draw this conclusion; he or she would contact gorilla experts and would systematically search through information from all the scientific reports about gorillas to check whether the general claim about gorilla color has even one counterexample. Only if none were found would the scientist then say, "Given all the evidence so far, all gorillas are black." The scientific community as a whole is even more cautious. It would wait to see whether any other biologists disputed the first biologist's claim. If not, only then would the community agree that all gorillas are black. This difference between scientific reasoning and ordinary reasoning can be summed up by saying that scientific reasoning has higher standards of proof.

Scientists don't rummage around the world for facts just so they can accumulate more facts. They gather specific facts to reach general conclusions, the "laws of science." Why? Because a general conclusion encompasses a great variety of specific facts, and because a general claim is more useful for prediction, understanding and explanation, which are the three primary goals of science. Scientists aren't uninterested in specifics, but they usually view specific data as a stepping stone to a broader or more general overview of how the world works. This point can be expressed by saying that scientists prefer laws to facts. Although there is no sharp line between laws and facts, facts tend to be more specific; laws, more general.

The power that generality provides is often underestimated. At the zoo, suppose you spot a cage marked "Margay" although the margay is out of sight at the moment. You have never heard of a margay, yet you can effortlessly acquire a considerable amount of knowledge about the margay, just by noticing that the cage is part of your zoo's new rare-feline center. It’s cat-like. If so, then you know it cannot survive in an atmosphere of pure nitrogen, that it doesn't have gills, and that it was not hatched from an egg. You know this about the unseen margay because you know on scientific authority that no cat-like beings can survive in nitrogen, that no cats have gills, and that no cats are hatched from eggs. You don’t know all this first-hand, but you’ve heard it indirectly from scientists, and you’ve never heard of any serious disagreement. Of course, scientific generalizations can be wrong. And maybe no experiment has ever been performed to test whether margays can live on pure nitrogen. But you are confident that if there were serious suspicions, the scientists would act quickly to run the tests. Knowing this about how scientists act, you rest comfortably with the generalizations and with your newly acquired knowledge about margays.