What is a Theory?
Defining the word theory is tricky. Scientists use it one way, the average Joe another. In casual parlance, a theory is basically an idea or thought. It probably has no carefully collected data to back it up, let alone any rigorous hypothesis testing or experiments. In the world of science, however, a theory is a broad explanation of a phenomenon or phenomena that is testable, falsifiable and has multiple lines of evidence. “Genuinely successful theories interconnect information from previously disparate areas of experience,” said Adolf Grünbaum, the Andrew Mellon Professor of Philosophy at the University of Pittsburgh. For example, fossil records, DNA evidence and biogeography are connected under the theory of evolution. A theory differs from a hypothesis in its scope. For example, I can have a hypothesis that if I throw a penny off the Empire State Building it will fall to the ground. But the theory of gravity goes vastly beyond throwing objects off a building. The theory of gravity
Scientific theories explain facts and laws, have predictive power, and so can be tested. Most people would rate facts and laws as more important than theories, thinking of theories as “guesses” or “hypotheses.” But for scientists, theories are the highest level of understanding. They are not just stepping-stones to more knowledge, but the goal of science. Examples of theories that justify great confidence because they work so well to explain nature include gravity, plate tectonics, atomic theory, and evolution.
A theory not only explains known facts; it also allows scientists to make predictions of what they should observe if a theory is true. Scientific theories are testable. New evidence should be compatible with a theory. If it isn’t, the theory is refined or rejected. The longer the central elements of a theory hold—the more observations it predicts, the more tests it passes, the more facts it explains—the stronger the theory. Many advances in science—the development of genetics after Darwin’s death, for example—have greatly enhanced evolutionary thinking. Yet even with these new advances, the theory of evolution still persists today, much as Darwin first described it, and is universally accepted by scientists.
WHAT IS A THEORY? Ed Pearlstein “Only a theory” is what creationists like to say about evolution. And that seems to carry greeat weight with some people. Such people don’t understand what that word means to a scientist. As used in science, “theory” does not mean the same thing as it does in everyday life. A theory is not a guess, hunch, hypothesis, or speculation. It is much more full-blown. A theory is built upon one or more hypotheses, and upon evidence. The word “built” is essential, for a theory contains reasoning and logical connections based on the hypotheses and evidence. Thus we have Newton’s theory of gravity and the motion of planets, Einstein’s theory of relativity, the germ theory of disease, the cell theory of organisms, plate tectonics (theory of the motion of land masses), the valence theory of chemical compounds, and theories of evolution in biology, geology, and astronomy. These theories are self-consistent and consistent with one another. Construction of good theories
The word “theory” means a number of different things, depending on the context. In the maths and sciences, for example, a theory is a tested and testable concept which is used to explain an occurrence. For students of the arts, “theory” refers to the non-practical aspect of their work, while laypeople refer to unproven ideas and speculation as theories. The multitude of meanings for this word can get confusing, but the intent is usually clear from the context; a mathematical paper talking about a theory, for example, is probably referring to a theory in the scientific sense. In English, the word dates back to 1592, when it was used to mean a concept or scheme. By the 1630s, scientists had co-opted the word, using it to describe an explanation or thought which was based on observation and testing. “To theorize” also emerged at around the same time. In the sciences, theories are created after observation and testing. They are designed to rationally and clearly explain a phenomenon. For e
