From _Skeptic_ vol. 1, no. 1, 1992, pp. 15-21.
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A SKEPTICAL MANIFESTO
By Michael Shermer, Ph.D.
On the opening page of the splendid little book _To Know a Fly_, Vincent
Dethier makes this humorous observation of how children grow up to
become scientists: "Although small children have taboos against stepping
on ants because such actions are said to bring on rain, there has never
seemed to be a taboo against pulling off the legs or wings of flies.
Most children eventually outgrow this behavior. Those who do not either
come to a bad end or become biologists" (1962, p. 2). The same could be
said of skepticism. In their early years children are knowledge junkies,
questioning everything in their view, though exhibiting little
skepticism. Most never learn to distinguish between inquisitiveness and
credulity. Those who do either come to a bad end or become professional
James Randi is one of these. So too are the founders and fellows of
the Committee for the Scientific Investigation of Claims of the
Paranormal (CSICOP), the predecessor to the _Skeptics Society_ whose
journal - the _Skeptical Inquirer_ - has set the standard toward which
this and other such publications must strive in the pursuit of
skepticism. But what does it mean to be skeptical? The word is a
troublesome one because of the heavy baggage it carries. The word has
different meanings for different people. (We had considered many names
but decided that as long as it is defined the word is a useful one.
Within the name we had also considered _Institute for Rational
Skepticism_, but rejected it for fear that we might become known as the
IRS, an organization about which many people are already skeptical!)
The Meaning and Limits of Skepticism
Skepticism has a long historical tradition dating back to ancient Greek
thought. The foremost historian of skepticism, Richard Popkin, tells us:
"Academic scepticism, so-called because it was formulated in the
Platonic Academy in the third century, B.C., developed from the Socratic
observation, 'All I know is that I know nothing'"(1979, p. xiii). Two of
the popular received meanings of the word by many people today are that
a skeptic believes nothing, or is closed minded to certain beliefs.
There is good reason for the perception of the first meaning. The
_Oxford English Dictionary (OED)_ gives this common usage for the word
skeptic: "One who, like Pyrrho and his followers in Greek antiquity,
doubts the possibility of real knowledge of any kind; one who holds that
there are no adequate grounds for certainty as to the truth of any
proposition whatever" (1971, Vol. 2, p. 2663).
Since this position is sterile and unproductive and held by virtually
no one (except a few confused solipsists who doubt even their own
existence), it is no wonder that so many find skepticism disturbing. A
more productive meaning of the word skeptic is the second usage given by
the _OED_: "One who doubts the validity of what claims to be knowledge in
some particular department of inquiry; one who maintains a doubting
attitude with reference to some particular question or statement."
The history of the word skeptic and skepticism is interesting and
often amusing. In 1672, for example, the _Philosophical Transactions_
VII records this passage: "Here he taketh occasion to examine
Pyrrhonisme or Scepticisme, professed by a Sect of men that speak
otherwise than they think." The charge is true. The most ardent skeptics
enjoy their skepticism as long as it does not encroach upon their most
cherished beliefs. Then incredulity flies out the window. I received a
call recently from a gentleman who professed to be a skeptic, wanted to
support the organization, and agrees with our skepticism about
everything except the power of vitamins to restore health and attenuate
disease. He hoped I would not be organizing any skeptical lectures or
articles on this field, which, he explained, has now been proven
scientifically to be effective. "Your field wouldn't be vitamin therapy
would it?" I inquired. "You bet it is!" he responded.
It is easy, even fun to challenge others' beliefs, when we are smug
in our certainty about our own. But when ours are challenged, it takes
great patience and ego strength to listen with an unjaundiced ear. But
there is a deeper flaw in pure skepticism. Taken to an extreme the
position by itself cannot stand. The _OED_ gives us this 1674 literary
example (Tucker _Lt. Nat._ II): "There is an air of positiveness in all
scepticism, an unreserved confidence in the strength of those arguments
that are alleged to overthrow all the knowledge of mankind." Skepticism
is itself a positive assertion about knowledge, and thus turned on
itself cannot be held. If you are skeptical about everything, you would
have to be skeptical of your own skepticism. Like the decaying sub-
atomic particle, pure skepticism uncoils and spins off the viewing
screen of our intellectual cloud chamber.
Skepticism alone does not produce progress. It is not enough simply
to reject the irrational. Skepticism must be followed with something
rational, or something that does produce progress. As the Austrian
economist Ludwig von Mises warned against those anti-communists who
presented no rational alternative to the system of which they were so
skeptical (1956, p. 112):
An anti-something movement displays a purely negative attitude. It
has no chance whatever to succeed. Its passionate diatribes
virtually advertise the program they attack. People must fight for
something that they want to achieve, not simply reject an evil,
however bad it may be.
Carl Sagan sounded a similar warning to the professional skeptics at
the 1987 CSICOP annual meeting: "You can get into a habit of thought in
which you enjoy making fun of all those other people who don't see
things as clearly as you do. We have to guard carefully against it" (in
Basil, 1988, p. 366).
The Rational Skeptic
The second popular notion that skeptics are closed-minded to certain
beliefs comes from a misunderstanding of skepticism and science.
Skeptics and scientists are not necessarily "closed-minded" (though they
may be since they are human). They may have been open-minded to a belief
but when the evidence failed to support the belief, they rejected it.
There are already enough legitimate mysteries in the universe for which
evidence provides scientists fodder for their research, that to take the
time to consider "unseen" or "unknown" mysteries is not always
practical. When the non-skeptic says, "you're just closed-minded to the
unknown forces of the universe," the skeptic responds: "We're still
trying to understand the known forces of the universe."
It is for these reasons that it might be useful to modify the word
skeptic with "rational." Again, it is constructive to examine the usage
and history of this word that is so commonly used. Rational is given as:
"Having the faculty of reasoning; endowed with reason" (_OED_, p. 2420).
And reason as "A statement of some fact employed as an argument to
justify or condemn some act, prove or disprove some assertion, idea, or
belief" (p. 2431). It may seem rather pedantic to dig through the
dictionary and pull out arcane word usages and histories. But it is
constructive to know how a word was intended to be used and what it has
come to mean. They are often not the same, and more often than not, they
have multiple usages such that when two people communicate they are
frequently talking at cross purposes. One person's skepticism may be
another's credulity. And who does not think they are rational when it
comes to their own beliefs and ideologies?
It is also important to remember that dictionaries do not give
definitions. They give usages. For a listener to understand a speaker,
and for a reader to follow a writer, important words must be defined
with semantic precision for communication to be successful. What I mean
by skeptic is the second usage above: "One who doubts the validity of
what claims to be knowledge in some particular department of inquiry."
And by rational: "A statement of some fact employed as an argument to
justify or condemn some act, prove or disprove some assertion, idea, or
belief." But these usages leave out one important component: the goal of
reason and rationality. The ultimate end to thinking is to understand
cause-and-effect relationships in the world around us. It is to know the
universe, the world, and ourselves. Since rationality is the most
reliable means of thinking, a rational skeptic may be defined as:
_One who questions the validity of particular claims of knowledge
by employing or calling for statements of fact to prove or
disprove claims, as a tool for understanding causality._
But what method shall we employ? Just being skeptical will lead us to
no conclusion other than the Socratic conclusion that we do not know.
The answer, in a word, is science, and the method, in two words, is the
Science and the Rational Skeptic
Needless to say, reviewing the usages and history of the word science
would be inappropriately long here, and I have already done this to a
certain extent in the essay at the end of this issue. For purposes of
clarity science will be taken to mean: _a set of cognitive and
behavioral methods designed to describe and interpret observed or
inferred phenomenon, past or present, aimed at building a testable body
of knowledge open to rejection or confirmation._
Science is a specific way of thinking and acting - a tool for
understanding information that is perceived directly or indirectly
("observed or inferred"). "Past or present" refers to both the
historical and the experimental sciences. Cognitive methods include
hunches, guesses, ideas, hypotheses, theories, paradigms, etc.;
behavioral methods include background research, data collection, data
organization, colleague collaboration and communication, experiments,
correlation of findings, statistical analyses, manuscript preparation,
conference presentations, publications, etc. This definition is
discussed in greater detail in the later essay. More controversial, and
less likely to find agreement among practitioners, is a definition of
the scientific method. In fact, one of the more insightful and amusing
observations on this problem was made by the Nobel laureate and
philosopher of science, Sir Peter Medawar (1969, p. 11):
Ask a scientist what he conceives the scientific method to be and
he will adopt an expression that is at once solemn and shifty-
eyed: solemn, because he feels he ought to declare an opinion;
shifty-eyed, because he is wondering how to conceal the fact that
he has no opinion to declare.
A sizable body of literature exists on the scientific method and
there is little consensus among the authors. This does not mean that
scientists do not know what they are doing. Doing and explaining may be
two different things. For the purpose of outlining a methodology for the
rational skeptic to apply to questionable claims, the following four
step process may represent, on the simplest of levels, something that
might be called the "scientific method":
1. _Observation_: Gathering data through the senses or sensory enhancing
2. _Induction_: Drawing general conclusions from the data. Forming
3. _Deduction_: Making specific predictions from the general
4. _Verification_: Checking the predictions against further
Science, of course, is not this rigid; and no scientist consciously
goes through such "steps." The process is a constantly interactive one
between making observations, drawing conclusions, making predictions,
and checking them against further evidence. This process constitutes the
core of what philosophers of science call the _hypothetico-deductive_
method, which involves "(a) putting forward a hypothesis, (b) conjoining
it with a statement of 'initial conditions', (c) deducing from the two a
prediction, and (d) finding whether or not the prediction is fulfilled"
(Bynum, Browne, Porter, 1981, p. 196).
Observations are what flesh out the hypothetico-deductive process and
serve as the final arbiter for the validity of the predictions. As Sir
Arthur Stanley Eddington noted: "For the truth of the conclusions of
science, observation is the supreme court of appeal" (1958, p. 9).
Through the scientific method we form the following generalizations:
_Hypothesis_: A testable statement to account for a set of observations.
_Theory_: A well-supported testable statement to account for a set of
_Fact_: Data or conclusions confirmed to such an extent it would be
reasonable to offer temporary agreement. (Adopted from Gould, 1983, p.
These may be opposed to a _construct_, or a non-testable statement to
account for a set of observations. The observation of living organisms
on Earth may be accounted for by God or by evolution. The first
statement is a construct, the second a theory. Most biologists would
even call evolution a fact by the above definition.
Through the scientific method we aim for:
_Objectivity_: The basing of conclusions on external validation.
_Mysticism_: The basing of conclusions on personal insights that lack
There is nothing wrong with personal insight. Many great scientists
attributed important ideas to insight, intuition, and other equally
difficult-to-define concepts. Alfred Wallace said that the idea of
natural selection "suddenly flashed upon" him during an attack of
malaria. Timothy Ferris called Einstein, "the great intuitive artist of
science." But insightful and intuitive ideas do not gain acceptance
until they are externally validated. As Richard Hardison explained
(1988, p. 259-260):
Mystical "truths," by their nature, must be solely personal, and
they can have no possible external validation. Each has equal
claim to truth. Tea leaf reading and astrology and Buddhism; each
is equally sound or unsound if we judge by the absence of related
evidence. This is not intended to disparage any one of the faiths;
merely to note the impossibility of verifying their correctness.
The mystic is in a paradoxical position. When he seeks external
support for his views he must turn to external arguments, and he
denies mysticism in the process. External validation is, by
definition, impossible for the mystic.
Science leads us toward:
_Rationalism_: The basing of conclusions on the scientific method. For
example, how do you know the Earth is round?
1. The shadow on the moon is round.
2. The mast of a ship is the last thing seen.
3. The horizon is curved.
4. Photographs from space.
Science helps us avoid:
_Dogmatism_: The basing of conclusions on authority rather than science.
For example, how do you know the Earth is round?
1. My parents told me.
2. My teachers told me.
3. My minister told me.
4. My textbook told me.
Dogmatic conclusions are not necessarily invalid but they do pose
another question: How did the authorities come by their conclusions? Did
they use science or some other means?
The Essential Tension Between Skepticism and Credulity
It is important too that we recognize the fallibility of science and the
scientific method. But within this fallibility lies its greatest
strength: self-correction. Whether mistakes are made honestly or
dishonestly, whether a fraud is unknowingly or knowingly perpetrated, in
time it will be flushed out of the system through the lack of external
verification. The cold fusion fiasco is a classic example of the
system's swift consequences for error and hasty publication.
Because of the importance of this self-correcting feature, there is
in the profession what Richard Feynman calls "a principle of scientific
thought that corresponds to a kind of utter honesty - a kind of leaning
over backwards." Feynman says: "If you're doing an experiment, you
should report everything that you think might make it invalid - not only
what you think is right about it: other causes that could possibly
explain your results" (1988, p. 247).
Despite these built in mechanisms science is still subject to a
number of problems and fallacies that even the most careful scientist
and rational skeptic are aware can be troublesome. We can, however, find
inspiration in those who have overcome them to make monumental
contributions to our understanding of the world and ourselves. Charles
Darwin is a sterling example of a scientist who struck the right balance
in what Thomas Kuhn calls the "essential tension" in science between
total acceptance of and devotion to the status quo, and an open
willingness to explore and accept new ideas (1962, 1977). This delicate
balance forms the basis of the whole concept of paradigm shifts in the
history of science. When enough of the scientific community
(particularly those in positions of power) are willing to abandon the
old orthodoxy in favor of the (formerly) radical new theory, then, and
only then can the paradigm shift occur.
This generalization about change in science is usually made about the
paradigm as a system, but we must recognize that the paradigm is a
cognitive framework in the minds of individuals. Darwinian scholar Frank
Sulloway identifies three characteristics of Darwin's intellect and
personality that mark him as one of the handful of giants in the history
of science who found the right balance (1991, p. 28): "First, although
Darwin indeed had unusual reverence for the opinions of others, he was
obviously quite capable of challenging authority and thinking for
himself." Second, "Darwin was also unusual as a scientist in his extreme
respect for, and attention to, negative evidence." Darwin included, for
example, a chapter on "Difficulties on Theory" in the _Origin of
Species_; as a result his objectors were rarely able to present him with
a challenge that he had not already confronted or addressed. And third
was Darwin's "ability to tap the collective resources of the scientific
community and to enlist other scientists as fellow collaborators in his
own research projects." Darwin's collected correspondence numbers
greater than 16,000 extant letters, most of which involve lengthy
discussions and question-and-answer sequences about scientific problems.
He was constantly questioning, always learning, confident enough to
formulate original ideas, yet modest enough to recognize his own
A fourth that might be mentioned is that Darwin maintained a good
dollop of modesty and cautiousness that Sulloway sees as "a valuable
attribute" that helps "prevent an overestimation of one's own theories."
There is much to be learned in this regard from Darwin's
_Autobiography_. Darwin confesses that he has "no great quickness of
apprehension or wit which is so remarkable in some clever men," a lack
of which makes him "a poor critic: a paper or book, when first read,
generally excites my admiration, and it is only after considerable
reflection that I perceive the weak points." Unfortunately many of
Darwin's critics have selectively quoted such passages against him, not
seeing the advantage Darwin saw in the patient avoidance of regrettable
mistakes made in haste (1892, p. 55):
I think that I have become a little more skillful in guessing
right explanations and in devising experimental tests; but this
may probably be the result of mere practice, and of a larger store
of knowledge. I have as much difficulty as ever in expressing
myself clearly and concisely; and this difficulty has caused me a
very great loss of time; but it has had the compensating advantage
of forcing me to think long and intently about every sentence, and
thus I have been often led to see errors in reasoning and in my
own observations or those of others.
His is a lesson in science and in life well worth learning. What
Sulloway sees as particularly special about Darwin was his ability to
resolve the essential tension within himself. "Usually, it is the
scientific community as a whole that displays this essential tension
between tradition and change," Sulloway observes, "since most people
have a preference for one or the other way of thinking. What is
relatively rare in the history of science is to find these contradictory
qualities combined in such a successful manner in one individual" (p. 32).
Carl Sagan summed up the essential tension between skepticism and
credulity in his CSICOP lecture on "The Burden of Skepticism":
It seems to me what is called for is an exquisite balance
between two conflicting needs: the most skeptical scrutiny of all
hypotheses that are served up to us and at the same time a great
openness to new ideas. If you are only skeptical, then no new
ideas make it through to you. You never learn anything new. You
become a crochety old person convinced that nonsense is ruling the
world. (There is, of course, much data to support you.)
On the other hand, if you are open to the point of gullibility
and have not an ounce of skeptical sense in you, then you cannot
distingush the useful ideas from the worthless ones. If all ideas
have equal validity then you are lost, because then, it seems to
me, no ideas have any validity at all" (in Basil, 1988, p. 366).
There is some hope that rational skepticism, and the vigorous
application of the scientific method, can help us navigate through the
treacherous straights between pure skepticism and unmitigated credulity.
The Tool of the Mind
Science is the best method humankind has devised for understanding
causality. Therefore the scientific method is our most effective tool
for understanding the causes of the effects we are confronted with in
our personal lives as well as in nature. There are few human traits that
most observers would call truly universal. Most would consent, however,
that survival of the species as a whole, and the achivement of greater
happiness of individuals in particular, are universals that virtually
every human being seeks. We have seen the interrelationship between
science, rationality, and rational skepticism. Thus, we may go so far as
to say that the survival of the human species and the attainment of
greater happiness for individuals depend on the ability to think
scientifically, rationally, and skeptically.
It is assumed that human beings are born with the ability to
perceive cause-and-effect relationships. When we are born we have no
cultural experience whatsoever. But we do not come into the world
completely ignorant. We know lots of things - how to see, hear, digest
food, track a moving object in the visual field, blink at approaching
objects, become anxious when placed over a ledge, develop a taste
aversion for noxious foods, and so on. We also inherit the traits our
ancestors evolved in a world filled with predators and natural
disasters, poisons and dangers, and risks from all sides. We are
descended from the most successful ancestors at understanding causality.
Our brains are natural machines for piecing together events that may
be related and for solving problems that require our attention. One can
envision an ancient hominid from Africa chipping and grinding and
shaping a rock into a sharp tool for carving up a large mammalian
carcass. Or perhaps we can imagine the first individual who discovered
that knocking flint would create a spark with which to start a fire. The
wheel, the lever, the bow and arrow, the plow - inventions intended to
allow us to shape our environment rather than be shaped by it - started
civilization down a path that led to our modern scientific and
In his discussion of the rewards of science, Vincent Dethier, whose
words opened this manifesto, runs through the pantheon of the obvious
ones - monetary, security, honor - as well as the transcendent: "a
passport to the world, a feeling of belonging to one race, a feeling
that transcends political boundaries and ideologies, religions, and
languages." But he brushes these aside for one "more lofty and more
subtle." This is the natural curiosity of humans in their drive to
understand the world:
One of the characteristics that sets man apart from all the other
animals (and animal he undubitably is) is a need for knowledge for
its own sake. Many animals are curious, but in them curiosity is a
facet of adaptation. Man has a hunger to know. And to many a man,
being endowed with the capacity to know, he has a duty to know.
All knowledge, however small, however irrelevant to progress and
well-being, is a part of the whole. It is of this the scientist
partakes. To know the fly is to share a bit in the sublimity of
Knowledge. That is the challenge and the joy of science (pp. 118-119).
Children are naturally are curious, inquisitive, and exploratory of
their environment. It is normal to want to know how things work and why
the world is the way it is. At its most basic level, this is what
science is all about. As Richard Feynman observed: "I've been caught, so
to speak - like someone who was given something wonderful when he was a
child, and he's always looking for it again. I'm always looking, like a
child, for the wonders I know I'm going to find - maybe not every time,
but every once in a while" (1988, p. 16). The most important question in
education is this: what tools are children given to understand the
On the most basic of levels we must think or die. Those who are alive
are thinking and using reason to a greater or lesser extent. Those who
use more reason, those who employ rational skepticism, will attain
greater satisfaction because they understand the cause of their
satisfaction. It cannot be otherwise. As Ayn Rand concluded in her
magnum opus _Atlas Shrugged_ (1957, p. 1012):
Man cannot survive except by gaining knowledge, and reason is his
only means to gain it . . . . Man's mind is his basic tool of
survival. Life is given to him, survival is not. His body is given
to him, its sustenance is not. His mind is given to him, its
content is not. To remain alive, he must act, and before he can
act he must know the nature and purpose of his action. He cannot
obtain his food without a knowledge of food and of the way to
obtain it. He cannot dig a ditch - or build a cyclotron - without
a knowledge of his aim and of the means to achieve it. To remain
alive, he must think.
Over three centuries ago the French philosopher and skeptic René
Descartes, after one of the most thorough skeptical purges in
intellectual history, concluded that he knew one thing for certain:
"Cogito ergo sum." "I think therefore I am."
By a similar analysis, to be human is to think. Therefore, to
_"Sum Ergo Cogito."
"I Am Therefore I Think."_
Basil, R. 1988. _Not Necessarily the New Age_. Buffalo: Prometheus
Bynum, W.F., E.J. Browne, R. Porter. _Dictionary of the History of
Science_. Princeton: Princeton University Press.
Darwin, C. 1892. _The Autobiography of Charles Darwin_. Francis Darwin
(Ed.). New York: Dover.
Dethier, V.G. 1962. _To Know a Fly_. San Francisco: Holden-Day.
Eddington, A. S. 1958. _The Philosophy of Physical Science_. Ann Arbor:
University of Michigan Press.
Feynman, R.P. 1988. _What Do You Care What Other People Think?_ New
Gould, S. J. 1983. _Hen's Teeth and Horse's Toes_. New York: W.W.
Hardison, R.C. 1988. _Upon the Shoulders of Giants_. New York:
University Press of America.
Kuhn, T. S. 1962. _The Structure of Scientific Revolutions_. Chicago:
University of Chicago Press.
_____ . 1977. _The Essential Tension: Selected Studies in Scientific
Tradition and Change_. Chicago: University of Chicago Press.
Medawar, P. 1969. _Induction and Intuition in Scientific Thought_.
Mises, L.V. 1956. _The Anti-Capitalistic Mentality_. New York: D. Van
_Oxford English Dictionary_. 1971. Oxford.
Popkin, R. H. 1979. _The History of Scepticism from Erasmus to Spinoza_.
Berkeley: University of California Press.
Rand, A. 1957. _Atlas Shrugged_. New York: Random House.
Sulloway, F. J. 1991. "Darwinian Psychobiography." A review of Charles
Darwin: A new Life by John Bowlby. _The New York Review of Books_,
Michael Shermer is Director of the _Skeptics Society_ and Assistant
Professor of History of Science at the Institute for Human Progress. He
taught psychology and the history of science for 11 years at Glendale
College, and occasionally teaches the history of science and culture at
Occidental College. He has published _Teach Your Child Science_ and co-
authored _Teach Your Child Math_ and _Mathemagics_ with Dr. Arthur
Benjamin. Dr. Shermer has just finished two books, _Heretic-Scientist_,
a biography of Alfred Russell Wallace, and _The Chaos of History_, on
the application of chaos theory to human history. He has also written
numerous cycling books based on a ten year professional career as a
ultra-marathon cyclist and competitor in the transcontinental _Race