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The other thing is, it's not sufficient to listen
to their opinions.
If you'd like them to really learn to think critically,
they have to understand why you're not providing them
with the truth.
The answer at the core, of course, is truth,
in their sense, doesn't exist.
You have to help them understand the scope.
Wherever you want them to think critically, they have to
understand that it's uncertain.
If it ain't uncertain, you don't need to think critically
about it, you need to memorize it.
That making any sense?
Critical thinking is fundamentally a tool
for dealing with uncertainty and complexity, and the uncertainty
that flows from complexity.
In science, this is relatively easy.
All science is temporary.
We don't like it, necessarily, but we can use the history
of science to help students understand that.
It was said of Newton that he was the luckiest person
in the human, in the history of humanity, because there was one
set of blueprints that God had used to design the universe,
and Newton had learned to read them.
That's what you call truth.
But it turns out that Newton's laws are a local first
approximation, sort of like trying to tell who you are
by looking at your ear.
A local first approximation.
They're only true at low gravity and zero speed.
They're not true, generally.
That was replaced by relativity except that relativity has this
little problem that it's clear it's not true, either.
And it's clear we won't know what is true, if ever, until we
figure out how to put relativity and quantum mechanics together,
or transcend one or both of them.
So ever since we've known that Newton wasn't true,
we've known we don't have truth in physics.
We know relativity isn't true, we know quantum mechanics
isn't true, we know for sure that Newton isn't true.
That's a lot of uncertainty.
Unless you want to talk about screws and levers,
that gets rid of physics.
So you can use the history in a field to show that the history
is, you don't just add truth to truth, you show that the old
[unclear audio] were only first approximations, which is very
different than adding truth.
It's not that you're building up a storehouse of golden eggs,
you're seeing that what you thought was true is only
a local approximation.
Hopefully not an illusion, but sometimes it is an illusion.
And then it's also good if you can figure out why that is.
Ronowski said the reason you can't have the truth in science
is because both words and equations express reality
as a metaphor.
You can't capture the oak tree in words and you can't capture
it in equations.
You can't capture your neighbor in words and you can't capture
her or him in equations.
You necessarily over simplify.
One philosopher of science wrote a paper entitled
"Inaccuracy: The Key Property of Physical Laws".
And what he said is, isn't it interesting how many of the
laws of physics apply perfectly to absolutely nothing?
They're about ideal gases, frictionless pullies,
and other imaginary universes.
Inaccuracy, the key property of scientific laws.
You can't capture all of reality.
The reason the Ideal Gas Law is called the Ideal Gas Law is,
no gas works that way.
It's a first approximation that works, usually, for hydrogen.
It works awfully, that is, it doesn't work even reasonably
well if you mix two gases like, say, argon and hydrogen,
because the argon doesn't see the hydrogen, so to speak.
So it's an Ideal Gas Law about ideal gases, but an ideal gas
is like an ideal president, you just don't get it.
Sometimes you get closer, sometimes you get further,
but you don't get ideal.
So you need to help the students understand where the uncertainty
comes from.
Another way that it's sometimes said, you know, some of you will
remember something called general semantics
and reification and the tendency to think that words
actually mean something specific when they don't.
This table is pretty specific and concrete and you can get
away with it.
But freedom, or equality, those don't have boundaries,
not nearly as clear.
So some of you in the humanities and social sciences
will have had to work through reification and general
semantics and other key sources of uncertainty, right?
Or just amphiboly, the tendency of words to change meaning
as you go through an argument.
It's very hard to keep all of the nuances of a word fixed
as you go through an argument.
Often the argument falls apart because it was based
on switching from one meaning of a word to, 20 pages later,
the word has come to mean something distinctly
different, amphiboly.
So whatever it is, you need to help the students understand
how much of what you teach is uncertain.
And that's the only zone in which you can expect
critical thinking.
And how can it be?
As students have sometimes asked, literally, if you've been
doing physics since Newton, how come you haven't got it
right yet?
[audience laughter].
How could that be?
You've been doing genetics since Mendel, and you're still finding
new forms of inherited stuff?
What is this, how many kinds of RNA that are inherited
are you going to come up with, 400?
A lot more than DNA turns out to be inherited,
irritatingly so, or promisingly so.
So write down an example or two that you can use to show
students that things are uncertain in what you teach
and how come they're uncertain.
Is that question clear to everybody?
(female speaker). [unclear audio].
(Dr. Nelson). How come they are uncertain?
Why is it you haven't found truth?
And why don't you expect to find truth next week?
(male speaker). I have a quick question
before I leave.
So much is said about the objectivity of science.
Those in the humanities and social sciences know that,
I should say, know that many of the things they do
are subjective.
But in science, students come into the classroom believing
that many aspects of science are objective.
Then how do you tell them that things are not really true?
(Dr. Nelson). The question is how
do you tell them that things are not really true?
We need to temper that.
I'll give you two pieces of an answer.
Notice I've been concentrating on physics.
I also concentrate on math.
When I first read Perry's book, as I said before lunch,
I found that I was in a state he calls sophomoric,
although I was already a professor.