CRITICAL THINKING AND INFORMAL LOGIC

Some important concepts for making and refuting arguments and for coherent and systematic reasoning:

Sources:
Nigel Warburton, Thinking from A to Z (2nd), Routledge, 2000)
Anthony Flew, A Dictionary of Philosophy, Random House, 1999 and How to Think Straight: An Introduction to Critical Reasoning (2nd), Prometheus Books, 1998.

ABSURD CONSEQUENCES MOVE: see reductio ad absurdum

Ad Hoc CLAUSES
"Clauses added to a hypothesis to make the hypothesis consistent with some new observation or discovered fact." (2, Warburton 96)
-happens when hypothesis threatened by a new 'inconvenient fact'
options:
-abandon hypothesis
-add special clause to general hypothesis

("There is a fine line between making a hypothesis more detailed in the light of further evidence and undermining its power as a generalization by adding numerous exception clauses." (3, Warburton 96)

Ad Hominem MOVE
Latin: "to the person"; Used in two major ways:
1-an "informal fallacy": used to shift attention from the point in question to some non-relevant aspect of the person making it.
This is a reproach to the person making it.

2-a legitimate demonstration of an opponent's inconsistency (much rarer use of the term)
"you too" (tu quoque) move

=GETTING PERSONAL: "attacking the character of the person with whom you are arguing rather than finding fault with his or her argument." (64, Warburton 96)
-a technique of rhetoric/ used to point out HYPOCRISY

ALTERNATIVE EXPLANATIONS
"ignored explanations of the phenomenon in question." (8, Warburton 96)
-the temptation to believe that because an explanation is consistent with known facts it must be the correct explanation

(especially when it is the one we would like to be true)

problem: this is wishful thinking that ignores possibility of other plausible alternatives

AMBIGUITY
"An ambigious word or phrase has two or more meanings." (9, Warburton 96)
-not the same as vague/vagueness
=imprecision in language
arises when a word or phrase can be interpreted in different ways.

Lexical Ambiguity: "when a word with two or more possible meanings is used so that the phrase or sentence in which it appears can be understood in more than one way." (9)
-Puns play on lexical ambiguity

Referential Ambiguity: "occurs when a word is used so that it could be taken to be referring to either of two or more things." (10)

Syntactical ambiguity: (amphiboly): "occurs when the order of words allows two or more interpretations." (10)

ANECTDOTAL EVIDENCE
(rash generalization)

"Evidence which comes from selected stories either of what has happened to you or to someone you know. In many cases this is very weak evidence and typically involves generalizing from a particular case." (15, Warburton 96)
-not all anectodal evidence is unreliable; can help to support or undermine a conclusion.
-Can be a way to begin an investigation.

ARGUMENT
"Reasons supporting a conclusion." (16, Warburton 96)
-contrast with "assertion".
-not to be confused with a 'quarrel': assertion-counter-assertion

SOUND ARGUMENT: "a valid argument (see validity) with true premises and so a true conclusion." (112ÅA Warburton 96)

see: deduction/validity/sound argument/induction

ASSERTION
"An unsupported statement of belief. Whenever you simply say that something is the case you make an assertion." (19, Warburton 96)
-confident assertion is no substitue for argument/ can be tedious to spell out everything, esp if others hold most of your assumptions

see: truth by authority/ assumptions/argument

ASSUMPTION
"An unstated premise, one that is taken for granted and never made explicit." (19, Warburton 96)
-is an ambigious term: can also mean stated premise that is the starting-point of an argument (see supposition)
-problem: when people try to discuss an issue on which they hold very different assumptions: can lead to confusion and misunderstandings
-yet: we have to make assumptions most of the time

BEGGING THE QUESTION
(Latin: petitio principii)

"Assuming the very point that is at issue." (24, Warburton 96)
-sometimes involves incorporating conclusion of the argument into one of the premises
-this is a circular argument
-a valid form of argument/ not a formal fallacy
-it is rather uninformative and irritating but not logically invalid.
NOT the colloquial "invite the question" or "suggest the question"

See: circular arguments

BITING THE BULLET
"Accepting the apparently unpalatable consequences which follow from principles which you are unwilling to jettison." (26, Warburton 96)
-often follow from redutictio ad absurdum refutations
-indicates deep disagreement on fundamental assumptions

CIRCULAR ARGUMENT
(see: begging the question)

-"A circular argument takes the form:

A because of B
B because of A

-When there is no independent reason for believing A or B, then this is described as viciously circular." (29, Warburton 96)
-Sometimes occurs in attempts to justify induction
-Circular arguments are not invalid: there is nothing wrong with them from a logical point of view; but they are also uninformative

COMPANIONS IN GUILT MOVE
"Demonstrating that the case in question is not unique." (30, Warburton 96)
-usually used to dilute force of an argument by showing that demands of consistency should lead arguer to apply same principles in further cases
=will have to bite the bullet and accept that further cases will have to be treated in the same way
or: explain what maeks present case different
-can also be used to excuse bad behaviour on the grounds that "everyone does it".

COMPLEX QUESTIONS
(compound questions)
"Questions with several parts but which have the appearance of simple questions." (32, Warburton 96)
-sometimes known as the "fallacy of many questions" (an informal fallacy)
-typically involve "begging the question": often assume a position on the very point that is at issue
-difficult to answer without seeming to accept the questioner's assumptions
-sometimes involves use of "false dichotomies"

CONCLUSION
"The main judgement arrived at in an argument." (33, Warburton 96)
-sometimes conclusions stated first, then reasons for support
-the conclusion only follows logically if certain assumptions about the conditions are made

see: sound argument (in argument)

CONSISTENCY
"Two beliefs are consistent if they can both be true, inconsistent if only one of them can be." (34, Warburton 96)
=need consistent application of principles

CONTRADICTION
"Two statements which cannot both be true because one denies the other." (35, Warburton 96)

DEDUCTION
"Valid reasoning (see : validity) from premises to conclusion." (39, Warburton 96)
-Dedutive arguments are truth-preserving

If you begin with true premises; then
The conclusion must be true

Deduction from true premises guarantees true conclusions (unlike induction)

DEMOCRATIC FALLACY
"The unreliable method of reasoning which treats majority opinions as revealed by voting as a source of truth and a reliable guide for action on every question." (40, Warburton 96)
=an informal fallacy

CONSENSUS/ TRUTH BY CONSENSUS: "taking statements to be true simply because they are generally agreed upon. …just because there is general agreement that something is true it doesn't follow that it is true." (123, Warburton 96)
-Problem: gullibility/wishful thinking/majority often ill-informed

See also: Truth by authority

EMPIRICAL
"Based on experience or observation." (49, Warburton 96)

ENTHYMEME
"An argument with a suppressed premise." (49, Warburton 96) ie a "tacic assumption", without which conclusion would be a non sequiter.

EQUIVOCATION
"A kind of lexical ambiguity in which the same word or phrase is used twice or more within an argument but with a different meaning in each case. The equivocator treats the different uses of the word or phrase as if they have the same meaning." (51, Warburton 96)

see: straw man/ sophistry/ wishful thinking

ETYMOLOGICAL FALLACY
"The unreliable and often misleading move from a word's original meaning to its current meaning." (52, Warburton 96)
-a form of the genetic fallacy/ and an informal fallacy
-etymology: the study of the origin of words
-problem: word doesn't always keep same meaning over time. Thus, most reliable meaning of word is current use rather than its derivation.

EX POST FACTO ARGUMENT
"results when an investigator forms a theory on the basis of certain evidence, then uses that evidence to affirm the theory." (21, shively)

FALLACY
See formal/informal fallacy
-Doesn't mean "false" (a form of rhetoric)

FALSE DICHOTOMY
"A misleading account of the available alternatives." (57, Warburton 96)
-dichotomy: division into two alternatives
-"A false dichotomy occurs when someone sets up a dichotomy in such a way that it appears there are only two possible conclusions when in fact there are further alternatives not mentioned." (57, Warburton 96)
-deliberate false dichotomies (as opposed to accidental) are a form of sophistry

black and white thinking: "classifying every particular case as an example of one of two extremes when in fact there is a range of possible positions that can be occupied within the extremes….occurs when you try to make the world fit very simple preconceived categories." (28, Warburton 96)

(sometimes in rare cases there really are two dichotomies)

FORMAL FALLACY
"Any invalid form of argument, that is, one in which the premises can be true without the conclusion necessarily being true (see also: non sequitur)" (58, Warburton 96)
-are not truth-preserving (unlike valid arguments): their structure does not guarantee a true conclusion from true premises"
-(even if conclusion turns out to be true, won't have been reached by a reliable method)

GENERALIZATION
(Rash Generalization/ anectodal evidence/prejudice and provinicialism)
-"A general statement based on insufficient evidence." (101, Warburton 96)

"It Never Did Me any Harm": "a common and particularly irritating form of rash generalization in which someone defends some unattractive practice on the grounds that they survived having the same thing done to them." (74, Warburton 96)
-often relies on anectdotal evidence
-generalizing from a single case
-can also be wishful thinking
-Arguing from a single case

GENETIC FALLACY
An informal fallacy of the form 'x originated from y, therefore x must now have some features in common with y', though usually the reasoning is implied rather than baldly stated." (62, Warburton 96)
-Not a reliable way of arguing.

Problem: just because one thing emerged from another it does not follow that the thing that emerged shares any important feature with its origin." (63, Warburton 96)

HUMPTYDUMPTYING
"Giving private meanings to words in common use." (67, Warburton 96)
-From Lewis Carroll, Through the Looking-Glass: 'When I use a word', Humpty Dumpty answers, in rather a scornful tone, 'it means just what I choose it to mean &endash; neither more nor less.' (67, Warburton 96)

See: stipulative definition

Ignoratio Elenchi
Latin: "missing the point" (see irrelevance).

INDUCTION
"The method of reasoning which moves from a number of empirical observations to a generalization." (72, Warburton 96)
-contrast: deduction.

We actually rely on inductive arguments all the time: "all our expectations about the future are based on generalizations from what has happened in the past." (72)

Problem: quantity of evidence needed for definitive conclusion &endash; will differ from case to case.

INFORMAL FALLACY
"Any faulty or unreliable type of argument apart from a formal fallacy." (72, Warburton 96)
-Informal fallacies can be perfectly valid forms of argument in terms of logical structure.

Examples:
-etymological fallacy

JARGON
(Gobbledygook/ Pseudo-Profundity/Smokescreen/Newspeak)

"The specialist terminology associated with a particular profession or area of interest." (77, Warburton 96)
="technical term": better label for specialist words needed to communicate effectively
-pejorative sense: language that is unnecessarily obscure

KNOCK-DOWN ARGUMENT
"An argument which completely refutes a position" (79, Warburton 96)

(example: if all truths are relative, then the theory that all truths are relative must itself be relative: defenders of relativism often treat it as if it were absolutely true).

NON SEQUITUR
(Latin: "does not follow")

"A statement which does not follow logically from the premises which precede it." (88, Warburton 96)
-any formal fallacy will have a non sequiter as its conclusion
formal fallacy = invalid form of argument
(conclusions don't follow from premises)

POST HOC ERGO PROPTER HOC
(Latin: "After this therefore because of this"/ 'whatever happened after this must have happened because of this.' 94)
-a kind of correlation=cause confusion

PREJUDICE
"A belief held without good reason or consideration of the evidence for or against it being true." (95, Warburton 96)
-Bias

PROVINCIALISM: "generalizing about the right way to behave on the basis of how people behave in your locale." (97, Warburton 96)

see: rash generalization

PREMISES
"Suppositions from which conclusions are derived. Premises are the parts of an argument which give reason for believing that the conclusion is true or false." (95, Warburton 96)

PROOF BY IGNORANCE
"An informal fallacy in which lack of known evidence against a belief is taken as an indication that it is true. However, ignorance of evidence against a position does not prove that there could not be evidence against it; at best it is only indirect support for it." (96, Warburton 96)
-making definitive conclusions simply based on lack of direct proof

RED HERRING
"A form of irrelevance which leads the unwary off on a false trail." (102, Warburton 96)
-red herring: a dried fish; when dragged across a fox's trail leads the hounds off on the wrong scent.
-Going off on irrelevant tangents; can be useful when debate time is limited

IRRELEVANCE: "shifting discussion away from the point at issue by bringing in matters which don't relate directly to it." (73, Warburton 96)

Politician's Answer (technique for avoiding straightforward replies to direct questions)/getting personal/anectdotal evidence

RATIONALIZATION
"Disguising the real reasons for acting in a certain way by giving a self-serving justification which, even if plausible, is not true." (102, Warburton 96)
-A form of wishful thinking

Everyone does it/ It never did me any harm

Reductio ad Absurdum
"Absurd Consequences Move
-a form of refutation of someone else's argument:
-"Proving that a position is false, or at least untenable, by showing that if true it would lead to absurd consequences." (1, Warburton 96)

problem: no common 'touchstone' for absurdity: one person's absurdity might be another's common sense
(unless a view implies a contradiction there is no way of demonstrating its absurdity).

REFUTATION
"Proof that a statement, allegation, or charge is untrue." (103, Warburton 96)
-shouldn't be confused with repudiation: repudiate = to deny (doesn't require evidence)

RELATIVISM
(if all truths are relative, then the theory that all truths are relative must itself be relative: defenders of relativism often treat it as if it were absolutely true).

RHETORIC
"The art of persuasion. Rather than giving reasons and presenting arguments to support conclusions, those who use rhetoric employ a battery of techniques, such as using emphatic assertion, persuader words and emotive language, to convince the listener or reader that what they say or imply is true." (105, Warburton 96)

related to PR/advertising

SHIFTING THE GOALPOSTS
"Changing what is being argued for in mid-debate." (107, Warburton 96)
-a very common move to avoid criticism: shifting the point to a related area more easily defended.

ZIG-ZAGGING: "jumping from one topic to another in a discussion as a defence against criticism." (137, Warburton 96)

Can be used as a form of rhetoric to avoid facing criticism

SLIPPERY SLOPE ARGUMENT
"A type of argument which relies on the premise that if you make a small move in a particular direction it may then be extremely difficult or even impossible to prevent a much more substantial move in the same direction." (108, Warburton 96)
-usually used to persuade people not to accept what seems to be an unimportant or small innocuous practice because it will inevitably lead to the legitimation of highly undesirable practices.

Related to: idea of drawing a line

Can often be used in rhetoric

SOME/ALL CONFUSION
"A kind of ambiguity that arises when the words 'some' or 'all' are omitted and the context does not make it absolutely clear which is intended." (110, Warburton 96)
-usually context an eliminate ambiguity, but not always

SOPHISTRY
"A display of cleverness which doesn't respect the principles of good reasoning but smuggles in unlikely conclusions under a cloak of sham argument." (111, Warburton 96)
-Includes techniques like: begging the question/circular arguments/equivocation/formal and informal fallacies/pseudo-profundity/rhetoric

Sophists: ancient Greek teachers who allegedly taught pupils how to win arguments by any means available (instrumental use of logic and reason)

SUPPOSITION
"A premise assumed (see: assumption) for the sake of argument but not necessarily believed; sometimes known as a presupposition.
-not presumed to be true (unlike assertions); they can help in finding out what is true.

Presupposition/ assumption

STIPULATIVE DEFINITIONS
"Definitions which are the result of conscious and explicit decisions about how a word or phrase is to be used, rather than definitions based on the analysis of how words are usually used." (113, Warburton 96)

-stipulative definitions in experimental sciences = operational definitions.

STRAW MAN
"A caricature of your opponent's view set up simply so that you can knock it down." (115, Warburton 96)

-straw man: a dummy made of straw used for target practice
-opposite of playing devil's advocate.

TRUTH BY AUTHORITY
"Taking statements to be true simply because an alleged authority on the matter has said that they are true." (121, Warburton 96)
-complication: need to determine appropriate level of skepticism case by case
-kowtowing: inappropriate deference to experts/being overly deferential.
-problem: when they speak outside their area of expertise (universal expertise)
-experts often disagree: need to assess type of controversy/question as well
-experts are also fallible/ often experts only in a narrow area

UNIVERSAL EXPERTISE: "proficiency in one field taken as an indicator of proficiency in an unrelated one." (125, Warburton 96)

see also: truth by consensus (democratic fallacy)

VALIDITY
"The truth-preserving quality of good deductive arguments. Valid arguments guarantee true conclusions provided that their premises are true." (128, Warburton 96)
-valid arguments with one or more false premises will not guarantee true conclusions: they may have true conclusions, but you can't be sure of this simply on the basis of their validity.
-validity shouldn't be confused with truth.
-validity concerns the quality of the structure of an argument
(statements are either true or false)
-arguments can never be true or false
-statements can never be valid or invalid
-only deductive arguments can be valid or invalid

*SOUND ARGUMENT: "a valid argument with true premises and so a true conclusion." (112, Warburton 96)

VESTED INTEREST
"Having a personal investment in the outcome of a discussion: standing to gain if a particular conclusion is reached. People who have vested interests in particular outcomes often distort evidence or are economical with truth in order to achieve their desired end." (130-1, Warburton 96)

WISHFUL THINKING
"Believing that because it would be nice if something were true, it must be true." (133, Warburton 96)
-extreme form = self-deception/ milder form = unwarranted optimism

Correlation = cause confusions / rationalization

Van Gogh Fallacy: relies on a weak analogy (from the idea that since Van Gogh was poor but struggled with his art, then if I am poor I also have the chance to be a world famous artist one day).