Guide to the Logical Fallacies
jum...@my-dejanews.com
And, on an upbeat note ... :-)
---------------------------------------------------------------------
Stephen's Guide to the Logical Fallacies
http://www.assiniboinec.mb.ca/user/downes/fallacy/index.htm
---------------------------------------------------------------------
Overview
********
The point of an argument is to give reasons in support of some
conclusion. An argument commits a fallacy when the reasons offered do
not, in fact, support the conclusion.
Each fallacy is described in the following format:
Name: this is the generally accepted name of the fallacy
Definition: the fallacy is defined
Examples: examples of the fallacy are given
Proof: the steps needed to prove that the fallacy is committed
Note: Please keep in mind that this is a work in progress, and
therefore should not be thought of as complete in any way.
Fallacies of Distraction
************************
Each of these fallacies is characterized by the illegitimate use of a
logical operator in order to distract the reader from the apparent
falsity of a certain proposition.
False Dilemma
-------------
Definition: A limited number of options (usually two) is given, while in
reality there are more options. A false dilemma is an
illegitimate use of the "or" operator.
Examples: (i) Either you're for me or against me.
(ii) America: love it or leave it.
(iii) Either support Meech Lake or Quebec will separate.
Proof: Identify the options given and show (with an example) that there
is an additional option. (Cedarblom and Paulsen: 136)
Argument From Ignorance (argumentum ad ignorantiam)
---------------------------------------------------
Definition: Arguments of this form assume that since something has not
been proven false, it is therefore true. Conversely, such an
argument may assume that since something has not been proven
true, it is therefore false. (This is a special case of a
false dilemma, since it assumes that all propositions must
ether be known to be true or known to be false.) As Davis
writes, "Lack of proof is not proof." (p. 59)
Examples: (i) Since you cannot prove that ghosts do not exist, they must
exist.
(ii) Since scientists cannot prove that global warming will
occur, it probably won't.
(iii) Fred said that he is smarter than Jill, but he didn't
prove it, so it must be false.
Proof: Identify the proposition in question. Argue that it may be true
even though we don't know whether it is or isn't.
(Copi and Cohen: 93, Davis: 59)
Slippery Slope
--------------
Definition: In order to show that a proposition P is unacceptable, a
sequence of increasingly unacceptable events is shown to
follow from P. A slippery slope is an illegitimate use of
the"if- then" operator.
Examples: (i) If we pass laws against fully-automatic weapons, then it
won't be long before we pass laws on all weapons, and
then we will begin to restrict other rights, and
finally we will end up living in a communist state.
Thus, we should not ban fully-automatic weapons.
(ii) You should never gamble. Once you start gambling you
find it hard to stop. Soon you are spending all your
money on gambling, and eventually you will turn to
crime to support your earnings.
(iii) If I make an exception for you then I have to make an
exception for everyone.
Proof: Identify the proposition P being refuted and identify the final
event in the series of events. Then show that this final event
need not occur as a consequence of P. (Cedarblom and Paulsen: 137)
Complex Question
----------------
Definition: Two otherwise unrelated points are conjoined and treated as
a single proposition. The reader is expected to accept or
reject both together, when in reality one is acceptable
while the other is not. A complex question is an
illegitimate use of the "and" operator.
Examples: (i) You should support home education and the God-given
right of parents to raise their children according to
their own beliefs.
(ii) Do you support freedom and the right to bear arms?
(iii) Have you stopped using illegal sales practises?
(This asks two questions: did you use illegal practises,
and did you stop?)
Proof: Identify the two propositions illegitimately conjoined and
show that believing one does not mean that you have to believe
the other. (Cedarblom and Paulsen: 86, Copi and Cohen: 96)
Appeals to Motives in Place of Support
**************************************
The fallacies in this section have in common the practise of appealing
to emotions or other psychological factors. In this way, they do not
provide reasons for belief.
Appeal to Force (argumentum ad baculum)
---------------------------------------
Definition: The reader is told that unpleasant consequences will follow
if they do not agree with the author.
Examples: (i) You had better agree that the new company policy is the
best bet if you expect to keep your job.
(ii) NAFTA is wrong, and if you don't vote against NAFTA
then we will vote you out of office.
Proof: Identify the threat and the proposition and argue that the
threat is unrelated to the truth or falsity of the proposition.
(Cedarblom and Paulsen: 151, Copi and Cohen: 103)
Appeal to Pity (argumentum ad misercordiam)
-------------------------------------------
Definition: The reader is told to agree to the proposition because of the
pitiful state of the author.
Examples: (i) How can you say that's out? It was so close, and besides,
I'm down ten games to two.
(ii) We hope you'll accept our recommendations. We spent
the last three months working extra time on it.
Proof: Identify the proposition and the appeal to pity and argue that
the pitiful state of the arguer has nothing to do with the truth
of the proposition.
(Cedarblom and Paulsen: 151, Copi and Cohen: 103, Davis: 82)
Appeal to Consequences (argumentum ad consequentiam)
----------------------------------------------------
Definition: The author points to the disagreeable consequences of
holding a particular belief in order to show that this
belief is false.
Example: (i) You can't agree that evolution is true, because if it were,
then we would be no better than monkeys and apes.
(ii) You must believe in God, for otherwise life would have
no meaning. (Perhaps, but it is equally possible that
since life has no meaning that God does not exist.)
Proof: Identify the consequences to and argue that what we want to
be the case does not affect what is in fact the case.
(Cedarblom and Paulsen: 100, Davis: 63)
Prejudicial Language
--------------------
Definition: Loaded or emotive terms are used to attach value or moral
goodness to believing the proposition.
Examples: (i) Right thinking Canadians will agree with me that we
should have another free vote on capital punishment.
(ii) A reasonable person would agree that our income
statement is too low.
(iii) Senator Turner claims that the new tax rate will reduce
the deficit. (Here, the use of "claims" implies that
what Turner says is false.)
(iv) The proposal is likely to be resisted by the bureaucrats
on Parliament Hill. (Compare this to: The proposal is
likely to be rejected by officials on Parliament Hill.)
Proof: Identify the prejudicial terms used (eg. "Right thinking
Canadians" or "A reasonable person"). Show that disagreeing
with the conclusion does not make a person "wrong thinking" or
"unreasonable". (Cedarblom and Paulsen: 153, Davis: 62)
Appeal to Popularity (argumentum ad populum)
--------------------------------------------
Definition: A proposition is held to be true because it is widely held to
be true or is held to be true by some (usually upper
crust) sector of the population. This fallacy is sometimes
also called the "Appeal to Emotion" because emotional
appeals often sway the population as a whole.
Examples: (i) If you were beautiful, you could live like this, so buy
Buty-EZ and become beautiful. (Here, the appeal is to
the "beautiful people".)
(ii) Polls suggest that the Liberals will form a majority
government, so you may as well vote for them.
(iii) Everyone knows that the Earth is flat, so why do you
persist in your outlandish claims?
(Copi and Cohen: 103, Davis: 62)
Changing the Subject
********************
The fallacies in this section change the subject by discussing the
person making the argument instead of discussing reasons to believe or
disbelieve the conclusion. While on some occasions it is useful to
cite authorities, it is almost never appropriate to discuss the person
instead of the argument.
Attacking the Person (argumentum ad hominem)
--------------------------------------------
Definition: The person presenting an argument is attacked instead of the
argument itself. This takes many forms. For example, the
person's character, nationality or religion may be
attacked. Alternatively, it may be pointed out that a
person stands to gain from a favourable outcome. Or,
finally, a person may be attacked by association, or by
the company he keeps.
There are three major forms of Attacking the Person:
(1) ad hominem (abusive): instead of attacking an assertion,
the argument attacks the person who made the assertion.
(2) ad hominem (circumstantial): instead of attacking an
assertion the author points to the relationship between the
person making the assertion and the person's circumstances.
(3) ad hominem (tu quoque): this form of attack on the person
notes that a person does not practise what he preaches.
Examples: (i) You may argue that God doesn't exist, but you are just
following a fad. (ad hominem abusive)
(ii) We should discount what Premier Klein says about
taxation because he won't be hurt by the increase.
(ad hominem circumstantial)
(iii) We should disregard Share B.C.'s argument because they
are being funded by the logging industry.
(ad hominem circumstantial)
(iv) You say I shouldn't drink, but you haven't been sober for
more than a year. (ad hominem tu quoque)
Proof: Identify the attack and show that the character or
circumstances of the person has nothing to do with the truth
or falsity of the proposition being defended.
(Barker: 166, Cedarblom and Paulsen: 155, Copi and Cohen: 97, Davis: 80)
Appeal to Authority (argumentum ad verecundiam)
-----------------------------------------------
Definition: While sometimes it may be appropriate to cite an authority to
support a point, often it is not. In particular, an appeal to
authority is inappropriate if:
(i) the person is not qualified to have an expert
opinion on the subject,
(ii) experts in the field disagree on this issue.
(iii) the authority was making a joke, drunk, or otherwise not
being serious
A variation of the fallacious appeal to authority is
hearsay. An argument from hearsay is an argument which
depends on second or third hand sources.
Examples: (i) Noted psychologist Dr. Frasier Crane recommends that
you buy the EZ-Rest Hot Tub.
(ii) Economist John Kenneth Galbraith argues that a tight
money policy s the best cure for a recession. (Although
Galbraith is an expert, not all economists agree on this
point.)
(iii) We are headed for nuclear war. Last week Ronald
Reagan remarked that we begin bombing Russia in five
minutes. (Of course, he said it as a joke during a
microphone test.)
(iv) My friend heard on the news the other day that Canada
will declare war on Serbia. (This is a case of hearsay; in
fact, the reporter said that Canada would not declare war.)
(v) The Ottawa Citizen reported that sales were up 5.9
percent this year. (This is hearsay; we are not n a
position to check the Citizen's sources.)
Proof: Show that either (i) the person cited is not an authority in the
field, or that (ii) there is general disagreement among the
experts in the field on this point.
(Cedarblom and Paulsen: 155, Copi and Cohen: 95, Davis: 69)
Anonymous Authorities
---------------------
Definition: The authority in question is not named. This is a type of
appeal to authority because when an authority is not named
it is impossible to confirm that the authority is an
expert.
However the fallacy is so common it deserves special
mention.
A variation on this fallacy is the appeal to rumour. Because
the source of a rumour is typically not known, it is not
possible to determine whether to believe the rumour. Very
often false and harmful rumours are deliberately started n
order to discredit an opponent.
Examples: (i) A government official said today that the new gun law
will be proposed tomorrow.
(ii) Experts agree that the best way to prevent nuclear war
is to prepare for it.
(iii) It is held that there are more than two million needless
operations conducted every year.
(iv) Rumour has it that the Prime Minster will declare
another holiday in October.
Proof: Argue that because we don't know the source of the
information we have no way to evaluate the reliability of the
information. (Davis: 73)
Style Over Substance
--------------------
Definition: The manner in which an argument (or arguer) is presented is
taken to affect the likelihood that the conclusion is true.
Examples: (i) Nixon lost the presidential debate because of the sweat on
his forehead.
(ii) Trudeau knows how to move a crowd. He must be right.
(iii) Why don't you take the advice of that nicely dressed
young man?
Proof: While it is true that the manner in which an argument is
presented will affect whether people believe that its
conclusion is true, nonetheless, the truth of the conclusion
does not depend on the manner in which the argument is
presented. In order to show that this fallacy is being
committed, show that the style in this case does not affect
the truth or falsity of the conclusion. (Davis: 61)
Inductive Fallacies
*******************
Inductive reasoning consists on inferring from the properties of a
sample to the properties of a population as a whole. For example,
suppose we have a barrel containing of 1,000 beans. Some of the beans
are black and some of the beans are white. Suppose now we take a
sample of 100 beans from the barrel and that 50 of them are white and
50 of them are black. Then we could infer inductively that half the
beans in the barrel (that is, 500 of them) are black and half are
white. All inductive reasoning depends on the similarity of the sample
and the population. The more similar the same is to the population as
a whole, the more reliable will be the inductive inference. On the
other hand, if the sample is relevantly dissimilar to the population,
then the inductive inference will be unreliable. No inductive
inference is perfect. That means that any inductive inference can
sometimes fail. Even though the premises are true, the conclusion
might be false. Nonetheless, a good inductive inference gives us a
reason to believe that the conclusion is probably true.
Hasty Generalization
--------------------
Definition: The size of the sample is too small to support the
conclusion.
Examples: (i) Fred, the Australian, stole my wallet. Thus, all
Australians
are thieves. (Of course, we shouldn't judge all
Australians on the basis of one example.)
(ii) I asked six of my friends what they thought of the new
spending restraints and they agreed it is a good idea.
The new restraints are therefore generally popular.
Proof: Identify the size of the sample and the size of the population,
then show that the sample size is too small. Note: a formal
proof would require a mathematical calculation. This is the
subject of probability theory. For now, you must rely on common
sense. (Barker: 189, Cedarblom and Paulsen: 372, Davis: 103)
Unrepresentative Sample
-----------------------
Definition: The sample used in an inductive inference is relevantly
different from the population as a whole.
Examples: (i) To see how Canadians will vote in the next election we
polled a hundred people in Calgary. This shows
conclusively that the Reform Party will sweep the polls.
(People in Calgary tend to be more conservative, and
hence more likely to vote Reform, than people in the
rest of the country.)
(ii) The apples on the top of the box look good. The entire
box of apples must be good. (Of course, the rotten
apples are hidden beneath the surface.)
Proof: Show how the sample is relevantly different from the
population as a whole, then show that because the sample is
different, the conclusion is probably different.
(Barker: 188, Cedarblom and Paulsen: 226, Davis: 106)
False Analogy
-------------
Definition: In an analogy, two objects (or events), A and B are shown to
be similar. Then it is argued that since A has property P,
so also B must have property P. An analogy fails when the
two objects, A and B, are different in a way which affects
whether they both have property P.
Examples: (i) Employees are like nails. Just as nails must be hit in the
head in order to make them work, so must employees.
(ii) Government is like business, so just as business must be
sensitive primarily to the bottom line, so also must
government. (But the objectives of government and
business are completely different, so probably they
will have to meet different criteria.)
Proof: Identify the two objects or events being compared and the
property which both are said to possess. Show that the two
objects are different in a way which will affect whether they
both have that property.
(Barker: 192, Cedarblom and Paulsen: 257, Davis: 84)
Slothful Induction
------------------
Definition: The proper conclusion of an inductive argument is denied
despite the evidence to the contrary.
Examples: (i) Hugo has had twelve accidents n the last six months, yet
he insists that it is just a coincidence and not his fault.
(Inductively, the evidence is overwhelming that it is his
fault. This example borrowed from Barker, p. 189)
(ii) Poll after poll shows that the N.D.P will win fewer than
ten seats in Parliament. Yet the party leader insists
that the party is doing much better than the polls
suggest. (The N.D.P. in fact got nine seats.)
Proof: About all you can do in such a case is to point to the strength
of the inference. (Barker: 189)
Fallacy of Exclusion
--------------------
Definition: Important evidence which would undermine an inductive
argument is excluded from consideration. The requirement
that all relevant information be included is called the
"principle of total evidence".
Examples: (i) Jones is Albertan, and most Albertans vote Tory, so Jones
will probably vote Tory. (The information left out is
that Jones lives in Edmonton, and that most people in
Edmonton vote Liberal or N.D.P.)
(ii) The Leafs will probably win this game because they've
won nine out of their last ten. (Eight of the Leafs'
wins came over last place teams, and today they are
playing the first place team.)
Proof: Give the missing evidence and show that it changes the
outcome of the inductive argument. Note that it is not
sufficient simply to show that not all of the evidence was
included; it must be shown that the missing evidence will
change the conclusion. (Davis: 115)
Fallacies Involving Statistical Syllogisms
******************************************
A statistical generalization is a statement which is usually true, but
not always true. Very often these are expressed using the word "most",
as in "Most conservatives favour welfare cuts." Sometimes the word
"generally" s used, as in "Conservatives generally favour welfare
cuts." Or, sometimes, no specific word is used at all, as in:
"Conservatives favour welfare cuts." Fallacies involving statistical
generalizations occur because the generalization is not always true.
Thus, when an author treats a statistical generalization as though it
were always true, the author commits a fallacy.
Accident
--------
Definition: A general rule is applied when circumstances suggest that an
exception to the rule should apply.
Examples: (i) The law says that you should not travel faster than 50
kph, thus even though your father could not breathe,
you should not have travelled faster than 50 kph.
(ii) It is good to return things you have borrowed. Therefore,
you should return this automatic rifle from the madman
you borrowed it from. (Adapted from Plato's Republic,
Book I).
Proof: Identify the generalization in question and show that it is not
a universal generalization. Then show that the circumstances
of this case suggest that the generalization ought not to
apply. (Copi and Cohen: 100)
Converse Accident
-----------------
Definition: An exception to a generalization is applied to cases where
the generalization should apply.
Examples: (i) Because we allow terminally ill patients to use heroin, we
should allow everyone to use heroin.
(ii) Because you allowed Jill, who was hit by a truck, to
hand in her assignment late, you should allow the
entire class to hand in their assignments late.
Proof: Identify the generalization in question and show how the
special case was an exception to the generalization.
(Copi and Cohen: 100)
Causal Fallacies
****************
It is common for arguments to conclude that one thing causes another.
But the relation between cause and effect is a complex one. It is easy
to make a mistake. In general, we say that a cause C is the cause of
an effect E if and only if:
(i) Generally, if C occurs, then E will occur, and
(ii) Generally, if C does not occur, then E will not occur ether.
We say "generally" because there are always exceptions. For example:
We say that striking the match causes the match to light, because:
(i) Generally, when the match is struck, it lights (except when
the match is dunked in water), and
(ii) Generally, when the match is not struck, it does not light
(except when it is lit with a blowtorch).
Many writers also require that a causal statement be supported with a
natural law. For example, the statement that "striking the match
causes it to light" is supported by the principle that "friction
produces heat, and heat produces fire".
Coincidental Correlation (post hoc ergo prompter hoc)
-----------------------------------------------------
Definition: The name in Latin means "after this therefore because of
this". This describes the fallacy. An author commits the
fallacy when it is assumed that because one thing follows
another that the one thing was caused by the other.
Examples: (i) Immigration to Alberta from Ontario increased. Soon
after, the welfare rolls increased. Therefore, the
increased immigration caused the increased welfare
rolls.
(ii) I took EZ-No-Cold, and two days later, my cold
disappeared.
Proof: Show that the correlation is coincidental by showing that:
(i) the effect would have occurred even if the cause did not occur,
or (ii) that the effect was caused by something other than the suggested
cause. (Cedarblom and Paulsen: 237, Copi and Cohen: 101)
Joint Effect
------------
Definition: One thing is held to cause another when in fact both are the
effect of a single underlying cause. This fallacy is often
understood as a special case of post hoc ergo prompter hoc.
Examples: (i) We are experiencing high unemployment which s being
caused by a low consumer demand. (In fact, both may be
caused by high interest rates.)
(ii) You have a fever and this is causing you to break out in
spots. (In fact, both symptoms are caused by the measles.)
Proof: Identify the two effects and show that they are caused by the
same underlying cause. It is necessary to describe the
underlying cause and prove that it causes each symptom.
(Cedarblom and Paulsen: 238)
Genuine but Insignificant Cause
-------------------------------
Definition: The object or event identified as the cause of an effect is a
genuine cause, but insignificant when compared to the
other causes of that event.
Note that this fallacy does not apply when all other
contributing causes are equally insignificant. Thus, it
is not a fallacy to say that you helped cause defeat
the Tory government because you voted Reform, for your
vote had as much weight as any other vote, and hence is
equally a part of the cause.
Examples: (i) Smoking is causing air pollution in Edmonton. (True, but
the effect of smoking is insignificant compared to the
effect of auto exhaust.)
(ii) By leaving your oven on overnight you are contributing
to global warming.
Proof: Identify the much more significant cause.
(Cedarblom and Paulsen: 238)
Wrong Direction
---------------
Definition: The relation between cause and effect is reversed.
Examples: (i) Cancer causes smoking.
(ii) The increase in AIDS was caused by more sex education.
(In fact, the increase in sex education was caused by the
spread of AIDS.)
Proof: Give a causal argument showing that the relation between
cause and effect has been reversed.
(Cedarblom and Paulsen: 238)
Complex Cause
-------------
Definition: The effect is caused by a number of objects or events, of
which the cause identified is only a part. A variation
of this is the feedback loop where the effect is itself
a part of the cause.
Examples: (i) The accident was caused by the poor location of the bush.
(True, but it wouldn't have occurred had the driver not
been drunk and the pedestrian not been jaywalking.)
(ii) The Challenger explosion was caused by the cold
weather. (True, however, it would not have occurred had
the O-rings been properly constructed.)
(iii) People are in fear because of increased crime. (True, but
this has lead people to break the law as a consequence
of their fear, which increases crime even more.)
Proof: Show that all of the causes, and not just the one mentioned,
are required to produce the effect.( Cedarblom and Paulsen: 238)
Missing the Point
*****************
These fallacies have in common a general failure to prove that the
conclusion is true.
Begging the Question (petitio principii)
----------------------------------------
Definition: The truth of the conclusion is assumed by the premises.
Often, the conclusion is simply restated in the premises
in a slightly different form. In more difficult cases,
the premise is a consequence of the conclusion.
Examples: (i) Since I'm not lying, it follows that I'm telling the truth.
(ii) We know that God exists, since the Bible says God exists.
What the Bible says must be true, since God wrote it
and God never lies. (Here, we must agree that God
exists in order to believe that God wrote the Bible.)
Proof: Show that in order to believe that the premises are true we
must already agree that the conclusion is true.
(Barker: 159, Cedarblom and Paulsen: 144, Copi and Cohen: 102, Davis: 33)
Irrelevant Conclusion (ignoratio elenchi)
-----------------------------------------
Definition: An argument which purports to prove one thing instead
proves a different conclusion.
Examples: (i) You should support the new housing bill. We can't
continue to see people living in the streets; we must have
cheaper housing. (We may agree that housing is important
even though we disagree with the housing bill.)
(ii) I say we should support affirmative action. White males
have run the country for 500 years. They run most of
government and industry today. You can't deny that this
sort of discrimination is intolerable. (The author has
proven that there is discrimination, but not that
affirmative action will end that discrimination.)
Proof: Show that the conclusion proved by the author is not the
conclusion that the author set out to prove.
(Copi and Cohen: 105)
Straw Man
---------
Definition: The author attacks an argument which is different from, and
usually weaker than, the opposition's best argument.
Examples: (i) People who opposed the Charlottown Accord probably just
wanted Quebec to separate. But we want Quebec to stay
in Canada.
(ii) We should have conscription. People don't want to enter
the military because they find it an inconvenience. But
they should realize that there are more important
things than convenience.
Proof: Show that the opposition's argument has been misrepresented by
showing that the opposition has a stronger argument. Describe
the stronger argument. (Cedarblom and Paulsen: 138)
Fallacies of Ambiguity
**********************
The fallacies in this section are all cases where a word or phrase is
used unclearly. There are two ways in which this can occur.
(i) The word or phrase may be ambiguous, in which case it has more
than one distinct meaning.
(ii) The word or phrase may be vague, in which case it has no
distinct meaning.
Equivocation
------------
Definition: The same word is used with two different meanings.
Examples: (i) Criminal actions are illegal, and all murder trials are
criminal actions, thus all murder trials are illegal.
(Here the term "criminal actions" is used with two
different meanings. Example borrowed from Copi.)
(ii) The sign said "fine for parking here", and since it was
fine, I parked there.
(iii) All child-murderers are inhuman, thus, no child-
murderer is human. (From Barker, p. 164; this is called
"illicit obversion")
(iv) A plane is a carpenter's tool, and the Boeing 737 is a
place, hence the Boeing 737 is a carpenter's tool.
(Example borrowed from Davis, p. 58)
Proof: Identify the word which is used twice, then show that a
definition which is appropriate for one use of the word would
not be appropriate for the second use.
(Barker: 163, Cedarblom and Paulsen: 142, Copi and Cohen: 113, Davis: 58)
Amphiboly
---------
Definition: An amphiboly occurs when the construction of a sentence
allows it to have two different meanings.
Examples: (i) Last night I shot a burglar in my pyjamas.
(ii) The Oracle of Delphi told Croseus that if he pursued the
war he would destroy a mighty kingdom. (What the Oracle
did not mention was that the kingdom he destroyed would
be his own. Adapted from Heroditus, The Histories.)
(iii) Save soap and waste paper. (From Copi, p. 115)
Proof: Identify the ambiguous phrase and show the two possible
interpretations. (Copi and Cohen: 114)
Accent
------
Definition: Emphasis is used to suggest a meaning different from the
actual content of the proposition.
Examples: (i) It would be illegal to give away Free Beer!
(ii) The first mate, seeking revenge on the captain, wrote in
his journal, "The Captain was sober today." (He
suggests,
by his emphasis, that the Captain is usually drunk.
From Copi, p. 117) (Copi and Cohen: 115)
Category Errors
***************
These fallacies occur because the author mistakenly assumes that the
whole is nothing more than the sum of its parts. However, things
joined together may have different properties as a whole than any of
them do separately.
Composition
-----------
Definition: Because the parts of a whole have a certain property, it is
argued that the whole has that property. That whole may
be either an object composed of different parts, or it
may be a collection or set of individual members.
Examples: (i) The brick wall is six feet tall. Thus, the bricks in the
wall are six feet tall.
(ii) Germany is a militant country. Thus, each German is
militant.
(iii) Conventional bombs did more damage in W.W. II than
nuclear bombs. Thus, a conventional bomb is more
dangerous than a nuclear bomb. (From Copi, p. 118)
Proof: Show that the properties in question are the properties of the
whole, and not of each part or member or the whole. If
necessary, describe the parts to show that they could not have
the properties of the whole. (Barker: 164, Copi and Cohen: 117)
Division
--------
Definition: Because the whole has a certain property, it is argued that
the parts have that property. The whole in question may
be either a whole object or a collection or set of
individual members.
Examples: (i) Each brick is three inches high, thus, the brick wall is
three inches high.
(ii) Because the brain is capable of consciousness, each neural
cell in the brain must be capable of consciousness.
Proof: Show that the properties in question are the properties of the
parts, and not of the whole. If necessary, describe the parts
to show that they could not have the properties of the whole.
(Barker: 164, Copi and Cohen: 119)
Non-Sequitur
************
The term non sequitur literally means "it does not follow". In this
section we describe fallacies which occur as a consequence of invalid
arguments.
Affirming the Consequent
------------------------
Definition: Any argument of the following form is invalid:
If A then B. B, therefore, A.
Examples: (i) If I am in Calgary, then I am in Alberta. I am in Alberta,
thus, I am in Calgary. (Of course, even though the
premises are true, I might be in Edmonton, Alberta.)
(ii) If the mill were polluting the river then we would see an
increase in fish deaths. And fish deaths have
increased. Thus, the mill is polluting the river.
Proof: Show that even though the premises are true, the conclusion
could be false. In general, show that B might be a consequence
of something other than A. For example, the fish deaths might
be caused by pesticide run-off, and not the mill.
(Barker: 69, Cedarblom and Paulsen: 24, Copi and Cohen: 241)
Denying the Antecedent
----------------------
Definition: Any argument of the following form is invalid:
If A then B. Not A, therefore, Not B.
Examples: (i) If you get hit by a car when you are six then you will die
young. But you were not hit by a car when you were six.
Thus you will not die young. (Of course, you could be
hit by a train at age seven.)
(ii) If I am in Calgary then I am in Alberta. I am not in
Calgary, thus, I am not in Alberta.
Proof: Show that even though the premises are true, the conclusion
may be false. In particular, show that the consequence B may
occur even though A does not occur.
(Barker: 69, Cedarblom and Paulsen: 26, Copi and Cohen: 241)
Inconsistency
-------------
Definition: The author asserts more than one proposition such that the
propositions cannot all be true. In such a case, the
propositions may be contradictories or they may be
contraries.
Examples: (i) Montreal is about 200 km from Ottawa, while Toronto is
400 km from Ottawa. Toronto is closer to Ottawa than
Montreal.
(ii) John is taller than Jake, and Jake is taller than Fred,
while Fred is taller than John.
Proof: Assume that one of the statements is true, and then use it as
a premise to show that one of the other statements is false.
(Barker: 157)
====================================================================
--- (Index of Fallacies) ---
Fallacies of Distraction
False Dilemma: two choices are given when in fact there are three
options
From Ignorance: because something is not known to be true, it is
assumed to be false
Slippery Slope: a series of increasingly unacceptable consequences
is drawn
Complex Question: two unrelated points are conjoined as a single
proposition
Appeals to Motives in Place of Support
Appeal to Force: the reader is persuaded to agree by force
Appeal to Pity: the reader is persuaded to agree by sympathy
Consequences: the reader is warned of unacceptable consequences
Prejudicial Language: value or moral goodness is attached to
believing the author
Popularity: a proposition is argued to be true because it is
widely
held to be true
Changing the Subject
Attacking the Person:
(1) the person's character is attacked
(2) the person's circumstances are noted
(3) the person does not practise what is preached
Appeal to Authority:
(1) the authority is not an expert in the field
(2) experts in the field disagree
(3) the authority was joking, drunk, or in some other way not
being serious
Anonymous Authority: the authority in question is not named
Style Over Substance: the manner in which an argument (or arguer)
is presented is felt to affect the truth of the conclusion
Inductive Fallacies
Hasty Generalization: the sample is too small to support an
inductive generalization about a population
Unrepresentative Sample: the sample is unrepresentative of the
sample as a whole
False Analogy: the two objects or events being compared are
relevantly dissimilar
Slothful Induction: the conclusion of a strong inductive argument
is denied despite the evidence to the contrary
Fallacy of Exclusion: evidence which would change the outcome of an
inductive argument is excluded from consideration
Fallacies Involving Statistical Syllogisms
Accident: a generalization is applied when circumstances suggest
that there should be an exception
Converse Accident : an exception is applied in circumstances where
a generalization should apply
Causal Fallacies
Post Hoc: because one thing follows another, it is held to cause
the other
Joint effect: one thing is held to cause another when in fact they
are both the joint effects of an underlying cause
Insignificant: one thing is held to cause another, and it does, but
it is insignificant compared to other causes of the effect
Wrong Direction: the direction between cause and effect is
reversed
Complex Cause: the cause identified is only a part of the entire
cause of the effect
Missing the Point
Begging the Question: the truth of the conclusion is assumed by the
premises
Irrelevant Conclusion: an argument in defense of one conclusion
instead proves a different conclusion
Straw Man: the author attacks an argument different from (and
weaker than) the opposition's best argument
Fallacies of Ambiguity
Equivocation: the same term is used with two different meanings
Amphiboly: the structure of a sentence allows two different
interpretations
Accent: the emphasis on a word or phrase suggests a meaning
contrary to what the sentence actually says
Category Errors
Composition: because the attributes of the parts of a whole have a
certain property, it is argued that the whole has that property
Division: because the whole has a certain property, it is argued
that the parts have that property
Non Sequitur
Affirming the Consequent: any argument of the form: If A then B,
B, therefore A
Denying the Antecedent: any argument of the form: If A then B,
Not A, thus Not B
Inconsistency: asserting that contrary or contradictory statements
are both true
Syllogistic Errors
Fallacy of Four Terms: a syllogism has four terms
Undistributed Middle: two separate categories are said to be
connecte because they share a common property
Illicit Major: the predicate of the conclusion talks about all of
something, but the premises only mention some cases
of the term in the predicate
Illicit Minor: the subject of the conclusion talks about all of
something, but the premises only mention some cases
of the term in the subject
Fallacy of Exclusive Premises: a syllogism has two negative
premises
Fallacy of Drawing an Affirmative Conclusion From a Negative
Premise: as the name implies
Existential Fallacy: a particular conclusion is drawn from
universal premises
Fallacies of Explanation
Subverted Support: The phenomenon being explained doesn't exist.
Non-support: Evidence for the phenomenon being explained is
biased.
Untestability: The theory which explains cannot be tested.
Limited Scope: The theory which explains can only explain one
thing.
Limited Depth: The theory which explains does not appeal to
underlying causes.
Fallacies of Definition
Too Broad: The definition includes items which should not
be included.
Too Narrow: The definition does not include all the items which
should be included.
Failure to Elucidate: The definition is more difficult to
understand than the word or concept being defined.
Circular Definition: The definition includes the term being
defined as a part of the definition.
Conflicting Conditions: The definition is self-contradictory.
References
For Educators...
Please feel free to download the entire text (50 K) in plain-brown
wrapper HTML (does not contain the last three sections - sorry).
Permission is granted to use, abuse and reproduce this document in any
way you wish provided (a) you don't claim copyright over it, (b) you
don't charge anyone for using it, and (c) you indicate its original
authorship. Read more on my views about copyright if you're curious.
13 August 1996
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
Patrick Piquet
Strange
I don't find the word 'go' in this post ?
Patrick Piquet
Andrew Grant
rgg. I assume the purpose of this post was to help people to spot them more
easily.
Andrew Grant.
Patrick Piquet wrote in message <7d7fbc$fas$1...@pollux.ip-plus.net>...
q314159265
[snip][snip][snip]....Strange
I don't find the word 'go' in this post ?
Patrick Piquet
To make -my- post Go-relevant, here is a open-ended
Go question: white plays A, the board is pretty much empty..
Black to play.....
5|. . . . . .
4|. . . . . .
3|. . # A . .
2|. O . . . .
1|. . . . . .
+-----------
A B C D E F
Simon Goss
>To make -my- post Go-relevant, here is a open-ended
>Go question: white plays A, the board is pretty much empty..
>Black to play.....
>
> 5|. . . . . .
> 4|. . . . . .
> 3|. . # A . .
> 2|. O . . . .
> 1|. . . . . .
> +-----------
> A B C D E F
>
--
Simon Goss
Paul Clarke
wrote:
[snip MIME stuff]
>To make -my- post Go-relevant, here is a open-ended
>Go question: white plays A, the board is pretty much empty..
>Black to play.....
>
> 5|. . . . . .
> 4|. . . . . .
> 3|. . # A . .
> 2|. O . . . .
> 1|. . . . . .
> +-----------
> A B C D E F
Without thinking, I play C2. Why do I have the feeling that horrible
things are about to happen to me? :-)
[snip more MIME stuff]
q314159265
and there is only -one- eye...
Interesting position, eh?
5|. . . . . .
4|. . 2 4 . .
3|. 3 # A . .
2|. O 1 . . .
Robert Jasiek
> 5|. . . . . .
> 4|. . . . . .
> 3|. . # A . .
> 2|. O . . . .
> 1|. . . . . .
What did, as Sam Sloan would name him, the Late, Great Manfred Wimmer
in games he started at 2x2 after appearing in some club as a go devil
and betting on winning? Are there any victims who might tell?
--
robert jasiek
http://www.snafu.de/~jasiek/
Paul Clarke
wrote:
[snip]
>If you play C2 (B), following this sequence, B captures -one- W stone,
>and there is only -one- eye...
>
>Interesting position, eh?
>
>2|. O 1 . . .
>1|. . . . . .
> +-----------
> A B C D E F
>
5|. . . . . .
4|. . O O . .
3|. # # O . .
2|. O # . . .
1|. 1 . . . .
+-----------
A B C D E F
Black 1 seems to make miai of capturing with A2 or making a second eye
with D2. Alternatively, Black could exchange D2 for E2 and then play
1. What am I missing?
This doesn't look like a good result for Black, though. How about
playing 3 in the original diagram at D2 immediately, leaving White to
worry about all the cutting points:
5|. . . . . .
4|. . O . . .
3|. . # O 2 4
2|. O # 1 3 .
1|. . . . . .
+-----------
A B C D E F
and now Black B4 looks hairy, but cutting at B3 doesn't seem to work
for White:
5|. 3 . . . . . . .
4|. 1 O . . . . . .
3|. 2 # O O O 6 . .
2|. O # # # 5 . 7 .
1|. 4 . . . . . . .
+-----------------
A B C D E F G H J
5|. # . . . . . . .
4|. # O . . . . . .
3|. O # O O O O . .
2|. O # # # # . # .
1|. O . . . . . . .
+-----------------
A B C D E F G H J
Too good for Black. Maybe White should play 2 at 3 and shut Black in.
6|. . 6 . . . . . .
5|. 2 3 . . . . . .
4|. 1 O 4 . . . . .
3|. 5 # O O O , . .
2|. O # # # . . . .
1|. . . . . . . . .
+-----------------
A B C D E F G H J
6|. . O . . . . . .
5|. O # . . . . . .
4|. # O O . . . . .
3|. # # O O O , . .
2|. O # # # . . . .
1|. . . . . . . . .
+-----------------
A B C D E F G H J
This looks good for White provided that the ladder works, so we need a
better move for Black somewhere.
Patrick Piquet
Sorry for my self-defeating post ...
But:
1) English is not my mother tongue
and I badly interpreted the subject of this
very _long_ post (once again, I am sorry).
2) Perhaps can you translate it into French
so that I can appreciate it's content
(I will be delighted) ;-)
3) Finally, to justify this post, you sent a Go problem
and suddenly ... other posts appeared. It' fun
No flame in this post and my first post
Cordially
Patrick Piquet
Simon Goss
>This looks good for White provided that the ladder works, so we need a
>better move for Black somewhere.
I'm having the same kind of difficulties as you on this problem, but...
White has played on the 2-2 and 3-4 points. Why are we so keen to stop
him making 2nd/3rd line territory and to make similar ourselves (1 move
behind)? Maybe we could leave this corner with aji for later and argue
that if White plays yet again he's overconcentrated?
How about the 16-16 point?
Or, if we wanted to play locally, how about
5|. . . . . .
4|. . . 1 . .
3|. . # O . .
2|. O . . . .
1|. . . . . .
+-----------
A B C D E F
With the idea of letting White take what he seems to be wanting and
plastering him with ataris from the outside?
Cheers,
--
Simon
Paul Clarke
<si...@gosoft.demon.co.uk> wrote:
>Yo Paul,
>
>>This looks good for White provided that the ladder works, so we need a
>>better move for Black somewhere.
>
>I'm having the same kind of difficulties as you on this problem, but...
>
>White has played on the 2-2 and 3-4 points. Why are we so keen to stop
>him making 2nd/3rd line territory and to make similar ourselves (1 move
>behind)? Maybe we could leave this corner with aji for later and argue
>that if White plays yet again he's overconcentrated?
Certainly plausible. In a game, I'd be inclined to take this a step
further and not play C3 in the first place, with the idea that
whatever move White plays next in the corner, the 2-2 stone is not
going to be ideally placed.
>
>How about the 16-16 point?
>
>Or, if we wanted to play locally, how about
>
> 5|. . . . . .
> 4|. . . 1 . .
> 3|. . # O . .
> 2|. O . . . .
> 1|. . . . . .
> +-----------
> A B C D E F
>
>With the idea of letting White take what he seems to be wanting and
>plastering him with ataris from the outside?
I think what White wants here is to not to make second line territory,
but to draw Black into a fight on ground that White has prepared.
Accordingly, the answer to 1 is probably a cross-cut :-).
Simon Goss
>Certainly plausible. In a game, I'd be inclined to take this a step
>further and not play C3 in the first place, with the idea that
>whatever move White plays next in the corner, the 2-2 stone is not
>going to be ideally placed.
Right. Or, if your 3-3 was there first, not to tenuki the 2-2 unless
you're going to tenuki the follow-up too.
>> 5|. . . . . .
>> 4|. . . 1 . .
>> 3|. . # O . .
>> 2|. O . . . .
>> 1|. . . . . .
>> +-----------
>> A B C D E F
>>
>>With the idea of letting White take what he seems to be wanting and
>>plastering him with ataris from the outside?
>
>I think what White wants here is to not to make second line territory,
>but to draw Black into a fight on ground that White has prepared.
>Accordingly, the answer to 1 is probably a cross-cut :-).
I'd be happy to play two ataris and a connection, then.
Cheers,
--
Simon
Barry Phease
Firstly the problem is black should not play at the 3-3 point in
response to the 2-2. If white wants to play that low, then black should
give up the corner and get all the outside. The 3-4 or 4-4 points are
much more playable.
> 5|. . . . . .
> 4|. . O O . .
> 3|. # # O . .
> 2|. O # . . .
> 1|. 1 . . . .
> +-----------
> A B C D E F
>
> Black 1 seems to make miai of capturing with A2 or making a second eye
> with D2. Alternatively, Black could exchange D2 for E2 and then play
> 1. What am I missing?
>
> This doesn't look like a good result for Black, though. How about
> playing 3 in the original diagram at D2 immediately, leaving White to
> worry about all the cutting points:
Of course black can live, but still this is dreadful for black.
> 6|. . 6 . . . . . .
> 5|. 2 3 . . . . . .
> 4|. 1 O 4 . . . . .
> 3|. 5 # O O O , . .
> 2|. O # # # . . . .
> 1|. . . . . . . . .
> +-----------------
> A B C D E F G H J
Why would black play 5 here? better at 1 below.
6|. 1 . . . . . . .
5|3 O # . . . . . .
4|. # O O . . . . .
3|. 2 # O O O . . .
2|. O # # # a . . .
1|. b . . . . . . .
+-----------------
A B C D E F G H J
a and b are then miai for black. Obviously a is sente for white but
still the result is better for black.
Instead of the double hane, white has to play as below
7|. . 5 . . . . . .
6|. 4 3 . . . . . .
5|. 2 1 . . . . . .
4|. # O . . . . . .
3|. . # O O O 7 . .
2|. O # # # 6 . . .
1|. . . . . . . . .
+-----------------
A B C D E F G H J
This seems about even.
--
Barry Phease
Paul Clarke
wrote:
>Paul Clarke wrote:
[snip]
>> 6|. . 6 . . . . . .
>> 5|. 2 3 . . . . . .
>> 4|. 1 O 4 . . . . .
>> 3|. 5 # O O O , . .
>> 2|. O # # # . . . .
>> 1|. . . . . . . . .
>> +-----------------
>> A B C D E F G H J
>
>Why would black play 5 here? better at 1 below.
Because I misread the follow-up sequence :-(.
>
>
> 6|. 1 . . . . . . .
> 5|3 O # . . . . . .
> 4|. # O O . . . . .
> 3|. 2 # O O O . . .
> 2|. O # # # a . . .
> 1|. b . . . . . . .
> +-----------------
> A B C D E F G H J
>
>a and b are then miai for black. Obviously a is sente for white but
>still the result is better for black.
I was thinking that White could answer 3 with 'b' and then hane when
Black played 'a', capturing the Black stones. However, this doesn't
work because the White centre stones are too short of liberties.