Today, let's theorize. The University of Houston's
College of Engineering presents this series about
the machines that make our civilization run, and
the people whose ingenuity created them.
A listener left a phone
message. I'd mentioned Darwin's theory of
evolution, and he said,
"Wait a minute; Darwin's theory wasn't about evolution. His theory was that evolution occurs by means of natural selection."
Warning flags went up. There was more here than met
the eye. When I turned to dictionaries I saw the
problem more clearly. The word theory has
shifted under our feet.
The classical dictionary definition says that a
theory is a mental plan or a systematic set of
principles. A theory, unlike a hypothesis, has been
verified. It has been shown to fit the
facts, and it has stood up against attempts to
prove it false. The atomic theory of matter and
Einstein's Theory of Relativity are good examples.
All the older dictionaries tell us that we're
talking slang when we use the word theory
for a hunch or a guess.
But that changes in dictionaries of current usage.
They tell us that a theory is a belief or a
proposal or a hypothesis. Theoretical
knowledge now means a tentative idea and one that's
been divorced from practice. The old meaning -- an
established body of intellectual understanding --
withered while I wasn't looking.
What Darwin proposed was not that evolution occurs
-- it obviously did. He set out to explain
why it occurs. He explained how natural
selection works. I expect that caller wanted me to
be more cautious in a world where you hear people
saying "Evolution is only a theory!" Evolution, of
course, has long been a theory in the old
sense of the word. But to call it a theory today is
to scoff at it.
Few people still use the word theory in its old
sense, and we have no new word to replace it.
Meanwhile, fields like math, physics, and
engineering absolutely depend on intellectual
constructs. To work in them, you have to
traffic in theory. Yet, according to current usage,
to be a theoretician is to be vague and
All this has a chilling effect in our schools.
Arithmetic, math, and science now have to be
results-oriented. Subjects that're inherently
theoretical (in the old sense of the word) are
being stripped of their theoretical subtlety.
Students can smell that subtlety a mile away. They
sense that they can shrug it off when the teacher
tries to introduce it. Textbooks try to teach
science by presenting solved examples rather than
asking students to deduce their own results.
We need to do something about all this. We need to
make analytical deduction respectable again. So
here's what I ask of you: The next time a friend
voices suspicions about something, and you find
yourself starting to say, "That's only a theory,"
stop and bite your tongue. Save that fine word
theory for established knowledge. Save it
for things like the photon theory of light,
evolution by natural selection, or the laws of
thermodynamics. Reserve the word theory for
established structures of knowledge. And give our
students a chance to see the kind of subtlety that
turns isolated facts into whole bodies of
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds