The Nature of Science and
Critical Thinking
-- Joe Heafner, M.S.
Catawba Valley Community College
Catawba Valley Astronomy Club
Lucile Miller Observatory
Contributing Editor, Sky & Telescope
Version 20070116
This presentation is freely available in various
formats from the author’s website,
http://www.sticksandshadows.com.
You can contact the author at
heafnerj@sticksandshadows.com.
This presentation is copyright 2006 by Joe Heafner.
“It is a capital mistake to theorize before one
has data. Insensibly one begins to twist facts
to suit theories, instead of theories to suit
facts.”
-- Sherlock Holmes in Arthur Conan Doyle’s A
Scandal in Bohemia (1891)
What Is Science?
What Isn’t Science?
After this presentation, you should be able to...
define “science”,
distinguish science from pseudoscience,
understand when science can be used and when
it cannot,
and apply science to get answers (this takes an
entire semester...or longer).
The American Association of Physics Teachers
(AmJPhys 67 (8), August 1999, p. 659) says:
“Science is the systematic enterprise of
gathering knowledge about the world and
organizing and condensing that knowledge into
testable laws and theories.”
“The success and credibility of science is
anchored in the willingness of scientists to: ”
“(1) expose their ideas and results to
independent testing and replication by other
scientists; this requires the complete and open
exchange of data, procedures and materials;”
“(2) abandon or modify accepted conclusions
when confronted with more complete or
reliable experimental evidence.”
“Adherence to these principles provides a
mechanism for self-correction that is the
foundation of the credibility of science.”
process
“Science is the systematic enterprise of
gathering knowledge about the world and
organizing and condensing that knowledge into
testable laws and theories.”
“The success and credibility of science is
anchored in the willingness of scientists to: ”
“(1) expose their ideas and results to
independent testing and replication by other
scientists; this requires the complete and open
exchange of data, procedures and materials;”
“(2) abandon or modify accepted conclusions
when confronted with more complete or
reliable experimental evidence.”
“Adherence to these principles provides a
mechanism for self-correction that is the
foundation of the credibility of science.”
What is your perception of scientists?
Astronomy is an observational science, not an
experimental science.
That which is not science, but pretends to be
science, is pseudoscience.
pseudo + science = false science
That which is assumed to be unexplainable
cannot be called science. All scientists search
for explanations that are assumed to exist.
Science cannot be used to get an answer that
doesn’t exist. Science has limitations!
A “scientific model” is a collection of concepts
that accounts for all existing observational and
experimental results and generates testable
predictions. Such a model does not necessarily
constitute anything tangible, like a model
airplane. Models explain things and generate
testable predictions.
When there are two or more competing models
for a phenomenon and all the models yield the
same results, Occam’s razor says that the
simplest model is the correct one. Nature
prefers simplicity.
One more thing...
Any scientific claim must be capable of being
falsified. This has nothing to do with whether
the claim is true or false!
Sanity Check! (Credit to Paul Hewitt)
Which of the following statements is a scientific
claim?
(1) Human beings will never set foot on the
Moon.
(2) Some of the laws that govern Nature cannot
be detected by scientists.
(3) It is quite possible that in some other galaxy
the laws of physics are fundamentally different
than the laws we are acquainted with in this
galaxy.
In your groups, come up with one scientifically
valid statement and one scientifically invalid
statement and discuss both statements’ merits.
Is the sky blue on a clear day?
How do you know?
Did someone tell you?
Did you see it for yourself?
Do you BELIEVE the sky is blue or do you
ACCEPT it as reality?
If someone were to tell you that they simply do
not believe the sky is blue on a clear day, what
would your response be?
Consider these questions...
Is Earth round?
Does Earth really spin?
Does Sun orbit Earth?
Is Earth’s rotational axis tilted?
Is Earth at the center of the Universe?
Do other planets orbit Earth?
Is there a supreme deity?
Does casual use of <5 mW handheld green
laser pointers ruin astrophotos?
Is there life elsewhere in the Universe?
If you answered “yes” or “no” without
considering the scientific validity of the
question,
considering HOW you know the answer,
or considering WHY you accept the answer,
then you’re operating under a “belief system”
rather than under valid science.
Scientists don’t “believe” the sky is blue on a
clear day! They accept it as reality because it
can be directly and repeatedly observed! (Note
the use of the word “repeatedly”!)
The sky IS blue on a clear day! See for yourself!
Science and belief systems can peacefully
coexist AS LONG AS we understand that they
have different, but not interchangeable,
purposes.
No true scientist will ever ask you to change
your beliefs. Sometimes, people who have a
vested interest in “getting something” from you
will ask you to change your beliefs. Scientists
don’t deal in beliefs.
Thinking about things as critically as possible
MAY lead YOU to change some of your beliefs,
but no scientist will ever try to make you
change your (spiritual) beliefs. Only YOU can
change YOUR beliefs.
You’re always free to believe anything you like,
but science restricts you to that which meets
the formal definition of scientific validity. Keep
the beliefs separate from the science!
Don’t take anyone’s word for anything! That
includes
teachers,
politicians,
lawyers,
scientists, and others! Some people rely on our
aversion to questioning authority to have their
way with us. Want evidence? Consider the
brands of clothes you’re wearing right now!
Why should we care? Well, consider an ordinary
box of straws.
It’s okay to question intellectual authority!
Those who tell you otherwise have something to
hide.
SHOW
SHOW
SHOW
SHOW
SHOW
SHOW
SHOW
ME
ME
ME
ME
ME
ME
ME
THE
THE
THE
THE
THE
THE
THE
EVIDENCE
EVIDENCE
EVIDENCE
EVIDENCE
EVIDENCE
EVIDENCE
EVIDENCE
BABY!
BABY!
BABY!
BABY!
BABY!
BABY!
BABY!
“Evidence in support of” is not equivalent to
“proof of”. Scientists don’t “prove right”
anything. We gather evidence.
“There is something special about the first day
of spring that allows one to balance an egg on
its end only on this day.”
Critical Thinking
is highly shunned in our modern society,
is seen as a threat to authorities outside of
the scientific community, especially the
business world,
is seldom addressed in science courses despite
lofty claims to the contrary,
and often requires questioning authority, which
is often seen as offensive,
isn’t universally defined. (!!!!)
“Why
should
we
subsidize
intellectual
curiosity?” -- Ronald Reagan, campaign speech,
1980
Critical Thinking
Tell students it’s okay (and necessary!) to
question what they’re told!
Tell students to question every number in their
textbooks!
Tell students to verify observations for
themselves!
Tell students to DEMAND EVIDENCE!
“The difference between faith and institutional
religion is like the difference between wisdom
and test scores. Faith looks beyond itself and
trusts; institutional religion looks mainly at
itself and controls.” -- Tom Ehrich, quoted in
The Charlotte Observer, Sunday, October 23,
2005, page P1.
Critical Thinking
Baloney Detection Kit, available for $5 from
http://www.skeptic.com
We need to teach how to recognize logical
fallacies. It’s not just for English classes any
more!
What better place to teach this than in a
science course!
We need to overcome innumeracy (the inability
to think with numbers)!
The probability that a woman of age 40 has
breast cancer is about 1%. If she has breast
cancer, the probability that she tests positive
on a screening mammogram is 90%. If she does
not have breast cancer, the probability that
she nevertheless tests positive is 9%. What are
the chances that a woman who tests positive
actually has breast cancer?
It is the night after Adam and Eve’s first day
in Paradise. Together, they watched Sun rise
and illuminate the marvelous trees, flowers, and
birds. At some point the air got cooler, and Sun
sank below the horizon. What is the probability
that Sun will rise again?
“I would hope that my faith is not so weak as to
require proof. I would hope that my critical
thinking ability is not so impaired as to require
faith.” -- Brian Hissom, M.A., N.C.C., L.P.C.
Consistent Terminology
The word “theory” connotes “uncertainty” to
laypersons, but this is incorrect usage for
scientists.
Substitute “body of knowledge known as...” for
“theory of...” (e.g. “body of knowledge known as
relativity” rather than “theory of relativity”).
Use “hypothesis” for an untested idea.
Who is to blame for muddled terminology?
Scientists! We’re terrible communicators!
Consistent Terminology
Substitute “evidence tells us” for “we believe”
(e.g. “Evidence tells us that electrons behave
this way.” rather than “We believe electrons
work this way.”).
Scientists don’t deal in beliefs. We deal in
evidence.
Who is to blame for muddled terminology?
Scientists! We’re terrible communicators!
Consistent Terminology
Substitute “confidence” for “faith” (e.g. “We
have confidence in our results.” rather than
“We have faith in our results.”).
Scientific results aren’t based on faith.
They’re based on evidence.
Who is to blame for muddled terminology?
Scientists! We’re terrible communicators!
find vs. find the value of
fact vs. opinion
possibility vs. probability
evidence vs. proof
critical thinking
vs.
promoting an agenda
Most students do not have the skills to “make
up their own minds”. That’s why they’re in
school.
Many “teachers” enter the classroom having
already decided not to teach true science.
It’s only a matter of time before a teacher or
school system is sued for incompetence. (Yay!
It’s finally happened! Science won!)
Why perpetuate the illusion of “debate” when
there’s NOTHING to debate? This is a tactic
of antiscientists and politicians.
So, what can we do as teachers (like it or not,
we’re all teachers) to better the situation? The
answers are simple, but disturbing to some.
And now, six really
radical, and potentially
offensive
and
subversive ideas:
1)
STOP
GIVING
PSEUDOSCIENCE
“EQUAL TIME” IN
THE
CLASSROOM,
UNLESS...
IT’S TO DIRECTLY
COMPARE
AND
CONTRAST
WITH
TRUE SCIENCE.
2)
Don’t
equate
questioning
and
skepticism
with
insubordination! That’s
so...corporate...and
educational.
3) Don’t equate “critical
thinking” to “promoting
an agenda” just because
you don’t agree with
what you’re asked to
think about.
4)
Get
over
the
unhealthy
obsession
with
“proof”
and
concentrate
on
“evidence”.
5) Cure innumeracy! Use
more numbers! Stop
promoting
numerical
ignorance!
6) Enforce consistently
correct
terminology!
Grade it!
References
Arons, Arnold B. Teaching Introductory Physics (Wiley, New York, 1997)
Bok, Derek. Our Underachieving Colleges: A Candid Look at How Much Students Learn
and Why They Should Be Learning More (Princeton, New York, 2006)
Gigerenzer, Gerd. Calculated Risks: How to Know When Numbers Deceive You (Simon &
Schuster, New York, 2002)
Sagan, Carl. The Demon-Haunted World: Science as a Candle in the Dark (Ballantine, New
York, 1996)
Shermer, Michael and Pat Linse. The Baloney Detection Kit (The Skeptics Society,
http://www.skeptic.com)
POP QUIZ!
More people are dying of cancer
than ever before. Therefore,
cancer
has
significantly
increased in resilience over the
years.
Every person who ate a dill
pickle in 1850 died. Therefore
we should ban dill pickles.
A grocery store manager claims
to have developed a cure for
the common cold and publishes
his discovery in a letter to the
editor of the local newspaper.
He claims that after taking one
dose of his cure, his cold went
away in about ten days.
Therefore his remedy must
have cured his cold.
A child is taking a hot shower. He
notices that that the water isn't as hot
as it was a minute ago, so he turns on
more hot water. He feels the water
getting cooler and turns up the hot
water again. After another two
minutes, the water feels cool but the
hot water is turned all the way on. The
child must have developed the
superhuman power to withstand high
temperatures.
There are some (many?) questions to
which modern science cannot provide
answers. Therefore, these questions
MUST have answers that involve
supernatural influences.
Evolution is just a theory.
Evolution must be correct because the
overwhelmingly
vast
majority
of
scientists say it is correct.
If astronomers can’t even agree on what
a planet is, then they can’t possibly be
right about evolution.
Carl Sagan was known to smoke pot.
Therefore, all of his scientific writings
are suspect.
Earth is such a complex system that it
simply must have had divine origins.
There must be something spiritually
significant about the Earth-Moon
system because Earth is the only planet
we know of from which the inhabitants
see a natural satellite and Sun with the
same angular size.
On the way here, I saw a car with
license plate BXP-3977. Of all the
license plates I could have seen, I saw
THAT ONE. There must be some
supernatural influence that led me to
see THAT particular license plate.
A Final Thought From
Phil Plait, the Bad
Astronomer (used with
his permission)
I know a place where the Sun never sets.
It’s a mountain, and it’s on the Moon. It sticks up so high that even as the Moon
spins, it’s in perpetual daylight. Radiation from the Sun pours down on there day
and night, 24 hours a day—well, the Moon’s day is actually about 4 weeks long, so
the sunlight pours down there 708 hours a day.
I know a place where the Sun never shines. It’s at the bottom of the ocean. A
crack in the crust there exudes nasty chemicals and heats the water to the boiling
point. This would kill a human instantly, but there are creatures there, bacteria,
that thrive. They eat the sulfur from the vent, and excrete sulfuric acid.
I know a place where the temperature is 15 million degrees, and the pressure would
crush you to a microscopic dot. That place is the core of the Sun.
I know a place where the magnetic fields would rip you apart, atom by atom: the
surface of a neutron star, a magnetar.
I know a place where life began billions of years ago. That place is here, the
Earth.
I know these places because I’m a scientist.
Science is a way of finding things out. It’s a way of testing what’s real. It’s what
Richard Feynman called “A way of not fooling ourselves.”
No astrologer ever predicted the existence of Uranus, Neptune, or Pluto. No
modern astrologer had a clue about Sedna, a ball of ice half the size of Pluto that
orbits even farther out. No astrologer predicted the more than 150 planets now
known to orbit other suns.
But scientists did.
No psychic, despite their claims, has ever helped the police solve a crime. But
forensic scientists have, all the time.
It wasn’t someone who practices homeopathy who found a cure for smallpox, or
polio. Scientists did, medical scientists.
No creationist ever cracked the genetic code. Chemists did. Molecular biologists
did.
They used physics. They used math. They used chemistry, biology, astronomy,
engineering.
They used science.
These are all the things you discovered doing your projects. All the things that
brought you here today.
Computers? Cell phones? Rockets to Saturn, probes to the ocean floor, PSP,
gamecubes,
gameboys,
X-boxes?
All by scientists.
Those places I talked about before—you can get to know them too. You can
experience the wonder of seeing them for the first time, the thrill of discovery,
the incredible, visceral feeling of doing something no one has ever done before,
seen things no one has seen before, know something no one else has ever known.
No crystal balls, no tarot cards, no horoscopes. Just you, your brain, and your
ability to think.
Welcome to science. You’re gonna like it here.
Thank you!