Inquiry, evidence, and argument are the powerful tools we use to accurately determine
what is. They provide foundation, stability, and balance to our human
spirit's ambitions, aspirations, optimism, hopes,
imagination, and distortions. They are the tools we use to
test assumptions and understand cause-and-effect
relationships in the world around us. The goal is accuracy in facts, analysis,
reason, and conclusions.
Facts are stubborn and the pen is mightier than the sword. Embrace facts as your
friends while maintaining a healthy skepticism. Be prepared to reevaluate your
opinions, interpretations, beliefs, assumptions, and conclusions as new information,
evidence, or analysis becomes available or is better understood. Develop,
refine, and apply your own theory of knowledge to
make your own best decisions. Stay curious.
- Curiosity, questioning, and learning.
- Expressing doubt.
- Observed phenomenon
- Logically valid conclusions drawn from the evidence presented.
- A course of reasoning aimed at demonstrating truth or falsehood.
- A set of statements in which one follows logically as a conclusion from
scientific method help us understand what is, while
and any mistake
in reasoning distort our perception and obscure our thinking.
Our minds are wired to select, interpret, and even
distort, evidence supporting the hypothesis “I'm OK”. Every day we
are subjected to manipulations, the influence of self-interested parties,
factual and logical errors, opinion presented as fact, hype, and a variety of
Writing and other communications can be evaluated using the criteria of: evidence provided, factual
accuracy, credibility of references, logical validity, depth of analysis, innovation and insight, relevance
and significance, balanced point of view, narrative skill, clarity, and presentation. Good writing
is clear thinking made visible. Learn to evaluate what you see, read, and hear;
think critically, ask questions and draw your own conclusions.
It is authentic and informative to describe the level of uncertainty
when communicating information. Have the courage and authenticity to say: “I don't know”,
or: “This is a rough estimate” or simply “This is what I believe”. We face measurement uncertainty, estimation error,
sampling error, limited evidence, ambiguous evidence, anecdotal evidence, conflicting evidence,
non-representative evidence, disputed evidence, misinformation, disinformation,
inference, extrapolation, tradition, alternative points of view, the
not-yet known, biased information, parochial points of view, taboos, and the unknowable when seeking answers to so many questions.
Distinguish between undisputed fact, widely accepted fact,
theory, expert opinion, hypothesis, minority opinion, filtered information, assumptions,
disingenuous statements, biased information,
dogma, faith, propaganda, and speculation when
reporting information, engaging in dialogue, or making arguments.
Separate anecdotes from systematic
studies. Consider how well the evidence represents an larger conclusion. When drawing conclusions from a set
of premises, comment on the level of certainty of each premise and the soundness of the
logic leading to each conclusion. It is a fact that 2+2=4 and that one weather
report forecasts a 60% chance of rain for tomorrow. Use
and significant figures to convey the range of uncertainly. Carefully distinguish what
you do know from what you do not know. Separate observation from interpretation. Scientific reports properly
include error bars, forecasts and estimates include confidence intervals and
ranges, and opinions reflect only a personal point of view that may not be widely
shared or well considered.
directed toward solving problems—involves seeking evidence, closely examining
reasoning and assumptions, analyzing basic concepts, and tracing out
implications of what is said and what is done. Knowing the rules of logic and
being alert to their fallacies is the first step in critical thinking. Critical thinkers consider a variety of questions when evaluating
information and drawing conclusions. For example:
- What problem are we working to solve?
- What are my goals, objectives, and
- What are the presenter's goals, objectives, biases,
beliefs, and motives?
- What question will best advance the dialogue?
- How can a question be best worded and presented?
- What are the sources of information and fact? Are the samples and examples
- What methods were used and what is the quality of information collection?
- What are the possible sources of error?
- What is the range of uncertainty and is it accurately described and
- What modes of judgment and reasoning are used?
- What concepts make the reasoning possible?
- What assumptions underlie the concepts in use? What alternative
interpretations and explanations fit the facts? Are these assumptions valid?
- What implications follow from the concepts and assumptions used?
- What is the point of view or frame of reference for this reasoning? Is the
point of view one-sided or
These considerations suggest specific questions such as:
- What is the most fundamental
- From what point of view can this problem best be approached?
- What assumptions are being made here? Do these assumptions make sense?
Why? What alternatives are sensible?
- What conclusion can best be inferred from the data? What alternative
conclusions does it also support?
- What is the fundamental concept
- Is conclusion “B” consistent with assumption, data, premise, or conclusion
- How could I check the accuracy
of these data? What alternative sources exist? Is this data reproducible?
Is the data systematic and representative?
- If we accept conclusion “A”, what else is
- Is this a credible source of information? Why?
Critical thinking is not negative thinking. It is careful thinking directed
toward deep understanding and insight. It recognizes that the obvious is
not always true, and many things that are true are not at all obvious.
Evidence is often ambiguous or conflicting and always has to be evaluated,
analyzed, and interpreted. Evidence is most reliable when:
- you can directly observe, examine, and probe the evidence yourself, in
detail, at length, without interference or restriction, without obstruction,
and from a variety of vantage points.
- you are alert and unimpaired by alcohol, drugs, distraction, expectations,
persuasion, vested interests,
sleep deprivation, delusion, stress, peer pressure, coercion, or strong
- you can verify the source, origin, authenticity, context, and
representative nature of the evidence.
- multiple senses cross check and provide consistent information regarding
the observation. Evidence is more complete and convincing when the way
something feels is consistent with the way it looks. For example, after seeing
a rock, you might pick it up to examine more closely. If the texture feels
like a rock and the weight is what you expect, then you have additional
evidence that what you are observing is a rock. However if the surface texture
is unusual, or the weight is unexpected, then perhaps you are examining an
artificial stone, or a hollow stone, or something quite different made of
- the evidence is public and accessible, so that several people can examine
it, share their findings, and discuss the similarities and differences,
consistencies and inconsistencies in their observations.
- the evidence can be observed repeatedly, so observations can be checked,
rechecked, and reexamined.
- the evidence can be observed under known or standard conditions that
assist its evaluation. As an example, water has very different appearance and
properties below freezing and above its boiling point.
- Careful records such as notes, photographs, audio and video recordings,
and diagrams are more reliable and should be used instead of unaided recall
when information is required later, after the evidence has been examined first
- observation is separated from interpretation. We observe the sunlight
appearing in the morning, traversing a path across the sky, and disappearing
in the evening. One interpretation is that the earth is the center of the
universe and the sun travels across the sky. An alternative interpretation is
that the earth rotates on its axis as it revolves around the sun.
- the data is a good representation of the issue being investigated.
Systematic information is more reliable than
anecdotal information. Data
obtained from an independent source is more reliable than data obtained,
provided, selected, or interpreted by someone with an interest in the
- whenever statistics are used to
summarize data and draw conclusions, ensure the statistics are correctly
Also, take care to separate observation from interpretation
to avoid drawing unfounded conclusions. Is that clear
liquid water or vinegar? Is that attractive woman he is with his wife, daughter,
co-worker, assistant, boss, or mistress? Have the people stopped asking questions because everything
is OK or because inquiry is being punished or otherwise surpressed? Does the sun move
across the sky, or does the earth move past the sun? What are alternative
explanations for what we are seeing? Consider this amusing story
where interpretation gets well ahead of observation.
Rather than examining evidence first hand, we often rely on secondary
information sources. These include gossip, rumor, hearsay, conversation, the
Internet, and information provided by various luminaries and authorities available as
publications, speeches, presentations, advertisements, endorsements, radio and
TV programs, and news items.
The English language use of the word “authority” has two very different
meanings. One meaning describes positional power—such as the
right to control, command, or determine—and the other describes expertise—an
accepted source of information. Evidence obtained from an authority has to be
carefully evaluated based on the expertise of the authority, while
respectfully disregarding the power, influence, fame, charisma,
attachment, or appeal
of the authority. Trust and verify. Exercise critical thinking. A common and
seductive fallacy is an
appeal to authority.
We are often mislead because of a natural tendency to trust some people and distrust
An authority often presents only a single point-of-view, and too often this
point-of-view advances a vested interest. One example of this is an Internet
site claiming to provide expert information on sleep problems as a public
service. However, the web site is created, paid for, and edited entirely by the
manufacturer of a particular prescription drug sleep aid. This is a manipulative
marketing tool, disguised as a source of objective information. It uses factual
statements to present a false message. Examine a
variety of view
apply critical thinking to help evaluate information provided by an authority,
or even by an aligned group of authorities.
Take particular care to evaluate the reliability of claims of divine or
religious experience, pronouncements by authorities, appeals to common sense,
the obvious, and other situations where information or conclusions are claimed
to be self-evident, beyond question, or beyond our comprehension. When a person
in power responds with a preemptive dismissal—refusing to seriously
consider an inquiry, or replying without responding by using
power, humiliation, ridicule, insult,
condescension, or humor—it is often because the evidence is absent or unsubstantiated.
Arrogance, belligerence, shouting, sneering, and repetition do not validate
evidence, instead these distractions should raise suspicions. Confident experts typically
welcome critical examination and discussion of their findings. Charlatans do
not. Retain a healthy skepticism. Challenge authority as needed to understand
and evaluate their claims and assess evidence. Challenge claims with a
respectful and tactful request to “show me” and “help me understand”.
Evidence can lead to dramatic conflicts with power. Consider the disputes
astronomer Galileo Galilei had with the Pope over the evidence Galileo gathered
to demonstrate that the sun, not the earth, was the center of the solar system.
Galileo observed the moons of Jupiter, the phases of Venus, movement of
sunspots, and light and shadow on the moon through his telescope. This evidence
convinced him that the earth revolved around the sun.
In 1630 Galileo completed his book
Dialogue Concerning the Two Chief World
Systems in which the
Earth-centered Ptolemaic model and the sun-centered Copernican models are
discussed and compared. After the book was printed in 1632 Pope Urban VIII
forbid its distribution; the case was referred to the
Inquisition and Galileo was summoned to Rome.
In 1633 Galileo was formally interrogated for 18 days and on April 30 Galileo
confessed (disingenuously no doubt) that he may have made the Copernican case in
the Dialogue too strong and he offered to refute it in his next book. The Pope
declined this offer and decided that Galileo should be imprisoned indefinitely.
Soon after, with a formal threat of torture, Galileo was examined by the
Inquisition and sentenced to prison and religious penances, the sentence was
signed by 6 of the 10 inquisitors. In a formal ceremony at the church of Santa
Maria Sofia Minerva, Galileo renounced his errors under oath. He was then put in
house arrest in Sienna. Galileo had the courage to speak truth to power, and the
wisdom to recant and save his life.
Galileo remained under house arrest, despite many medical problems and a
deteriorating state of health, until his death in 1642. Finally On October 31,
1992, the Roman Catholic Church admitted that it had erred in its 359-year-old
persecution of Galileo.
And then there was “Watergate”.
On the night of June 17, 1972, five men were arrested for breaking into
Democratic National Convention offices, apparently to repair illegal wiretaps
that had been installed on a previous occasion. Republican leadership denied any
knowledge of the wiretap. However, Washington Post reporters Carl Bernstein and
Bob Woodward relentlessly pursued the story, skillfully interviewing many frightened
people, stitching together bits of evidence, gathering facts, posing well formed
questions, and finally breaking the story wide open. As a result, on August 9,
1974, President Richard M. Nixon resigned the presidency of the United States to
avoid further investigation of his involvement and a likely impeachment.
Both of these examples rely on the fallacy of “appeal
to authority” where the argument is based on the authority,
power, and position of
the person making the claims, e.g. the pope and the president, rather than on
observable phenomenon. This presents the difficult choice of deciding based on
who you know or what you know.
Facts are stubborn. When you have to choose between following
the evidence and following orders, do your homework and go with the evidence.
Reject the claim that “might makes right.” The facts are likely to
prevail in the long term. Have the courage to
speak truth to power. The entertaining Hans Christian Andersen story,
reminds us to follow the evidence and retain a healthy skepticism.
Dismiss Irrelevant Information
Much of the information we are exposed to is irrelevant, distracting,
distorting, and not suitable evidence. These various non sequiturs—inferences
or conclusions that do not follow from the premises—were recognized and named by
the ancient Greeks, yet they continue to be prevalent today. Here is a brief
description of these seductive fallacies of irrelevance:
- Ad ignorantiam—from ignorance—This is the fallacy of claiming a
statement is either true or false without having evidence or any valid reason
supporting the claim.
- Ad vericundium—appeal to authority—This is the fallacy of
appealing to the power, position, or fame of the person making a claim rather
than to their expertise. This is discussed at length under the topics
“Evaluating Authority” and “Evidence and power” above.
- Post hoc ergo propter hoc—after this, therefore because of
this—This is the fallacy of concluding that because one event follows
another, the first caused the second. Concluding that a rainstorm was caused
by a rain dance is an example of this fallacy. This fallacy sneaks in when
‘the sun rose after the rooster crows’ becomes ‘the sun rose because the
rooster crows’. In fact, causality is a
complex topic and is difficult to prove. John Stewart Mills proposed his
“canons of induction” also know as “Mills
Methods” as a test for
establishing that “A” causes “B”. This is an important basis for the
Be careful to use the word “because” only to describe a cause and effect
relationship that you know exists.
- Ad populum—appeal to the people—This is the fallacy of
accepting something as fact simply because many other people also believe it
to be true.
- Ad baculum—appeal to force—This is the fallacy that “might makes
right”; accepting as correct the point of view or opinion of someone willing
to use force to suppress inquiry, alternative points-of-view, or contrary
evidence. As an example, frustrated mothers sometimes answer their misbehaving
and defiant three-year-olds by saying “because I'm the mother”.
provide many more consequential examples throughout history.
- Ad misericordiam—appeal to pity—This is the fallacy of accepting a
point-of-view or opinion of someone because they deserve our
example, someone might argue they deserve a raise by saying they might lose
their house if they don't get more money.
- Ad hominem—argument against the man—In this fallacy the character
of an expert is attacked (or praised) as an attempt to discredit (or
establish) the information they provide. An example is discrediting Bill
Clinton's foreign policy because he had improper sexual liaisons. Advancing a
hominem fallacy crosses the line from argument to attack and can easily
become a precursor to hate. It is dangerous because
it promotes the false belief that destroying the
person can eliminate the unwanted or inconvenient information or idea.
- Accident and Converse Accident—drawing hasty conclusions—are fallacies
inferring that each member of a group share the characteristics of the group,
or that the group is characterized by the attributes of one particular member.
These are the fallacies of stereotyping and non-representative samples. The
logical fallacy of accident, also called destroying the exception or a
dicto simpliciter ad dictum secundum quid,
is a fallacy occurring when an exception to the generalization is ignored.
Applying a stereotype that does not
accurately describe an individual is an example of this type of fallacy. The
logical fallacy of converse accident (also called reverse accident, destroying
the exception or a
secundum quid ad dictum simpliciter)
is a fallacy that can occur when an exception to a generalization is wrongly
It is surprising that these fallacies are so common, even though they have
been well known for thousands of years. When someone persists in obscuring evidence
with these fallacies, they are being careless,
ignorant, biased, manipulative, or malicious.
Don't be persuaded.
Recognize Faulty Reasoning
Know the rules of logic and be alert for their fallacies. Even if evidence is accurate and relevant, it can be easily used in a variety
of invalid arguments to draw wrong conclusions from improper inferences.
Resolve ambiguity and challenge equivocation. Recognize and avoid these fallacies of ambiguity:
- Petitio principii—a request for the premise—also known as
circular reasoning or
begging the question.
It is a fallacy for a premise to rely in any way on the conclusion. For
example, explaining that “Joe is not here because he does not go to parties”
provides no information. It is equivalent to saying “Joe is not at this party
because Joe does not go to parties.” More subtle examples are common and often
go unrecognized or unchallenged.
a question on an unproven assumption—It is deceitful to pose an
unsubstantiated statement or opinion in the form of a question, yet it is
often done. Parents are being manipulative when they ask their child “Would
you like to be a good boy and go to bed now?” The coupling of “being a good
boy” with the request to “go to bed now” establishes an unproven contingency
because a bad boy might choose to go to bed now or a good boy might choose to
stay up longer.
- Equivocation—Exploiting ambiguous language—Many words have several, often
disparate meanings. Confusing these meanings is the
Consider this joke as an example: Mom to teenage daughter leaving on a date:
“Now be good dear.” Boyfriend remarking to his girlfriend after a steamy date:
“Wow, you really were good!”
in a lump—This fallacy exploits an ambiguous grammatical construct. A sign
stating “No Smoking Permitted” can be interpreted to mean that it is
permissible to not smoke, but it is also permissible to smoke, since smoking
is not specifically prohibited by the ambiguous language.
based on emphasis—Aristotle originally used this to describe differences in
meaning resulting from differences in the pronunciation of words. For example,
the phrase “I resent that letter” can be read to mean the letter was sent
again, or the letter was seen as offensive, depending on the accent of the
second word. More recently this fallacy is used to describe quotations taken
out of context, a headline that screams about some minor detail, or the “catch” hidden in the fine print and ignored by the sales pitch.
- Category Mistake—Not recognizing the composite from the collected
elements—For example, complaining that you can't find any forest here, all you
see is a bunch of trees.
- Composition Error—incorrectly projecting attributes of a part onto the
whole—For example, since Joe is a good player, and he plays for team X, then
team X must be a good team.
- Division Error—incorrectly projecting attributes of the whole onto each
component part—For example, to say “XYZ is a good corporation, so I am sure
that Mr. X who works there must be a fine fellow” is invalid. Also, to say
that “Suzie lives in a big house, so I'm sure she has a big bedroom” is also
invalid. Another form of this error is illustrated by this example: Dogs often
run stray, the Chinese Shar-pei is a breed of dog, so I'm sure they often run
- False dilemma—exploiting ambiguous complements—Declaring that “you are
either with us or against us” presents a false dilemma because “against us” is
not an accurate set complement (i.e. encompasses everything else) of “with us”.
The dilemma is false because it ignores the middle ground. In this example
it is possible to primarily agree
on some issues, primarily disagree on others, have partial
agreement or disagreement on issues, and to have no established position on
Awake and Aware:
Our perceptions are more accurate when we are alert, aware, and conscious of
our environment. A good night's sleep, attention focused on the present task,
and a clear head help us to see the world as it is. Fatigue, alcohol, drugs,
stress, strong emotions, chaos, multitasking, and distractions all impair our
senses and judgments. Trust evidence that was gathered with a clear head.
- “You're entitled to your own opinions, but you're not entitled to your own
facts.” ~ Senator
Daniel Patrick Moynihan
- “Facts are stubborn.”
- “It ain't what you don't know that gets you into trouble. It's what you
know for sure that just ain't so.” ~
- “The quality of our thinking is given in the quality of our questions ~
Foundation for Critical Thinking
- “Trust and verify.” ~
- “Eschew obfuscation.”
- “The further you get from power the closer you get to the truth” ~
- “It is not obvious what is obvious.”
- “A lie unchallenged becomes the truth.” ~
- “Truth is strong enough by itself to convince, and should never be
imposed by force.” ~ Matthieu Richard
- “Our questions cleanse our answers.” ~ Krista Tippett
- “Seek truth from facts.” ~
- “When all else fails, men turn to reason.“ ~ Abba Eban
- “To argue with a person who has renounced the use of reason is like
administering medicine to the dead.” ~
- “Reality is always your friend.”
- “Character is tested whenever power clashes with evidence.” ~ Leland R.
- “For a successful technology, reality must take precedence over public
relations, for Nature cannot be fooled.” ~ Richard P. Feynman
A Rulebook for Arguments, by Anthony Weston
Influence: The Psychology of Persuasion, by Robert B. Cialdini
Telling Lies: Clues to Deceit in the Marketplace, Politics, and Marriage,
by Paul Ekman
Root Cause Analysis : A Tool for Total Quality Management, by Paul F.
Introduction to Logic,
by Irving M. Copi, Carl Cohen
Principles of logic, by Alex C Michalos
Six Thinking Hats: An essential approach to business management,
by Edward de Bono
An Encyclopedia of Claims,
Frauds, and Hoaxes of the Occult and Supernatural, by The James Randi
Extraordinary Popular Delusions & the Madness of Crowds,
by Charles Mackay
Breaking the Spell: Religion as a Natural Phenomenon, by Daniel C.
Skeptic Reading Room Materials that may help you separate fact from
fiction and manage the level of skepticism you are comfortable with.
New Suit, by Hans Christian Andersen
Tools of Thinking: Understanding the World Through Experience and Reason,
video course taught by James Hall, University of Richmond
by Harry G. Frankfurt
Six Pillars of Self-Esteem,
by Nathaniel Branden
The Theory of Knowledge,
Bertrand Russell (1926), for The Encyclopaedia Britannica
Galileo and the Inquisition, by Jose Wudka
Galileo and the Church,
by Julian A. Smith
All the President's Men, by Bob Woodward, Carl Bernstein
The Foundation and
Center for Critical Thinking
aim to improve instruction in primary and secondary schools, colleges and
Maps of Bounded Rationality: A Perspective on Intuitive Judgment and Choice,
Nobel Prize Lecture, December 8, 2002 by Daniel Kahneman
The Emperor’s Dilemma: A Computational Model of Self-Enforcing
Norms, by Damon Centola, Robb Willer, and Michael Macy