What is a Theory?
By: Monica Heger
http://www.lifeslittlemysteries.com/301-what-is-a-theory.html
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 also explains the motion of planetary
bodies and orbiting satellites. So, a hypothesis is like a mini-theory. It attempts to explain an event,
and is testable and falsifiable like a theory is, but on a more narrow scale.
Hypotheses and theories are part of the scientific method — the process of asking and answering
questions by experimentation. The method exists to ensure that science is as accurate as possible in
explaining the world and that arguments rely on observable evidence. The main components of the
scientific method are that experiments should be repeatable, so other scientists can verify or nullify
the results; data should be collected by observation and experimentation; and experiments should
be documented and shared.
Theories are formed after numerous hypotheses are vetted using the scientific method. Hypotheses
are tested, data is collected, and the results are documented, shared and retested. Then a theory
that explains the data and predicts the outcomes of future experiments is formed. Typically,
researchers in different fields of study tend to rely on different methods — ones deemed the best
suited for their subjects or objects of study.
One component of a theory that can frustrate scientists and non-scientists alike is that a theory is
never proven and can always be revised. Experiments testing a theory either corroborate it or falsify
it. Even Isaac Newton’s laws of gravity were revised after 200 years, when Albert Einstein found
flaws and devised his theory of relativity.
In general, a law is said to be without exception, such as the second law of thermodynamics, which
says isolated systems that are not in equilibrium move from more ordered to less ordered states (or
less energy available to do work). Very few theories become laws. Michael Weisberg, associate
professor of philosophy at the University of Pennsylvania, said in the future even fewer theories are
likely to become laws, since theories and laws are so frequently revised.
“We can accumulate incredible amounts of evidence and say this is unlikely to be untrue, but we can
never give a proof,” Weisberg said.
On the other hand though, scientists do not look fondly upon those who pooh-pooh scientific
theories such as evolution as being just a theory. “It is skullduggery,” said Grünbaum. Yes, evolution
is a theory, but a theory supported by an enormous body of evidence.
“Ultimately, to say something is a theory in science is an honorific,” Weisberg said, meaning it
commands esteem or respect based on the many tests it has withstood.