...from a middle school teacher's planning guide.
"Your teacher is trying to demonstrate to you that anything and everything is open to dispute. In
fact, a rather famous theorem in the philosophy of science, the Duhem-Quine
theorem, states that it is impossible to conclusively disprove any
scientific hypothesis. That includes such hypotheses as the earth is flat,
photography steals the soul of the object being photographed, and apples
are highly toxic to humans. To hold on to such hypotheses, it may be
necessary to put forth some rather farfetched explanations of what we can
observe, but it can always be done.
In fact, science does not work by conclusively and indisputably refuting
bad hypotheses. Instead, hypotheses stand or fail on their ability to
explain known observations, and to predict the outcome of observations that
haven't been performed yet. Let's take the flat earth versus round earth
hypotheses as an example. A round earth is the most stable shape according
to gravitational theory; a flat earth would tend to collapse toward the
center, and people standing near the edges would feel a gravitational pull
toward the center of the flat surface instead of perpendicular to the
surface. Your teacher could counter that gravitational theory is wrong;
magic holds us to the earth. This may be true, but it doesn't explain why
gravitational theory works so well at explaining how things fall, and the
observed trajectories of the planets and their moons. You could tell your
teacher that photographs of the earth from space show that it is round,
just like the globe model in your classroom. He could counter that those
photographs are government fakes. Perhaps so, but we can see that other
planets and moons are round; wouldn't it make more sense to say that the
earth is round, too? Your teacher could say that the earth is special and
different. You could ask how numerous people have sailed or flown around
the earth if the earth is flat. He would have to say that every one of
these people, separated as they are in time and space, belongs to the same
great conspiracy aimed at brainwashing us into supposing that the earth is
round. You could ask him about the communications networks that are linked
by satellite - how can you have satellites orbiting a flat earth? He might
then tell you that there really aren't any satellite links - everything is
connected by wires, or a close-packed array of relay antennas.
We could go on and on, and I bet that in your classroom you HAVE gone on
and on. As you see, there is no single fact you could tell your teacher
that he couldn't dispute in some way. If you step back and look at it,
though,what kind of world would it have to be if your teacher were right?
Gravity doesn't function here like it does everywhere else in the solar
system, there's a huge conspiracy reaching across hundreds of years to
convince us (for no apparent reason) that the earth is round instead of
flat, the progression of the seasons, and even of day and night, are
controlled by the gods. Eventually, a reasonable person would have to
concede that it would make a lot more sense to agree that the earth is
indeed round.
There are some other theories to explain things that do not meet this test
of scientific reasonableness, yet are still put forth and defended by many
people in society. This example of the flat earth hypothesis lets you see
how difficult it is to change someone's mind when they're set on some
strange or unrealistic theory. It also lets you see that just if a theory
"can't be disproven" doesn't necessarily mean that it is correct, or that
it should be taken seriously for very long."