Critical thinking
Chapter 5
The practice of argument-reconstruction
The first step in reconstructing an argument is to make a list of the argument’s premises and conclusion as concisely and clearly as possible.
Making such a list is only the first step towards a complete reconstruction.
Expressive epithet: terms used to refer to some person, group or other entity but that characterize the entity referred to for rhetorical purposes.
When reconstructing arguments we should strive to display the logical relationships in an argument in the simplest, clearest and most familiar ways possible.
This is not always possible, and doing it will sometimes distract us from other points we are trying to make.
Not only do actual statements of arguments typically include a lot of material that is inessential to the argument, they often exclude some of what is essential to the argument.
Our task is to make the argument fully explicit.
A proposition is implicit: the proposition is part of the argument intended by the arguer but it has not actually been stated by the arguer.
To make a proposition explicit: to state it.
Connecting premise: the premise which you have to make explicit in order to make an argument valid.
Usually, when people give arguments, the premises they give explicitly will be only those which pertain to the particular facts or subject matter they are talking about.
Arguers very often leave implicit the more general assumptions they make.
We cannot assume that whenever an argument, as explicitly given, is neither valid nor inductively forceful, the intended argument is valid or inductively forceful.
It is not always the case that the arguer is implicitly relying on an appropriate connecting premise.
In other cases, the implicit connecting premise is just not true, in which case the argument is unsound.
Connecting premises are usually generalisations.
Covering generalisations need not be hard generalisations.
In such a case the inference from generalisation to instance is inductive rather than deductive.
Generalisations of the ‘All A are B’ sort are themselves conditionals, except they are generalised. The same goes for ‘No A are B’ form.
Very often, when people assert conditionals, they do so on the basis of some covering generalisation.
Connecting premises are almost always necessary, but they can fail to be sufficient to bring out the real basis of an argument.
When a proposition stated by the arguer is irrelevant to the reasoning that delivers the conclusion, that proposition should not be included in a reconstruction of the argument.
Why not include irrelevant material?
The truth-values of the premises actually advanced by an arguer can be more or less relevant to the soundness of the argument. Sometimes is is highly relevant that a given premise is false, sometimes is its much less so. It depends upon the nature of the mistake, and upon the role played in the argument by the premise.
Ambiguity
In reconstructing arguments, we have to eliminate any ambiguities in the original statement of the argument.
A primary purpose of reconstruction is to represent the propositions that constitute an argument in the clearest way.
There is not guarantee that we will not change or distort the arguer’s thinking, but there is no point in allowing ambiguous language to remain unchanged. We can simply not evaluate an argument if we do not know exactly what argument we are evaluating.
If we cannot decide between two interpretations of an ambiguity, we must give both interpretations of the argument, and evaluate the two arguments independently.
Vagueness
Important for critical reasoning are words whose meanings are vague.
We often have the feeling that these things are bad, or that they are good, without any precise idea of what they mean.
What they signify is typically a whole group or cluster of things that are not unified in any exact way.
(Like liberal or love).
In reconstructing arguments, the best thing to do with vague words is simply to eliminate them.
Many of the most rhetorically highly charged words in public discourse are vague. Eliminating them four our argument-reconstructions achieves two things:
The best thing to do with ambiguous or vague language is to replace it with language that is not vague or ambiguous.
The aim is to employ language that will express the intended propositions without ambiguity or vagueness.
But, this is not always possible.
Soft generalisations are very often expressed without any quantifier at all.
Since there is often confusion over the difference between hard and soft generalisations, we should, when constructing arguments, always make clear whether a generalisation is hard or soft. (The one exception to this is the case of statements about cause and effect).
The way to eliminate the ambiguity is to add an explicit quantifier.
The scope of generalisation
Subjects of generalisations: what the generalisations are about.
The scope of generalisations: how big the subject is.
It can be wider and narrower.
(For example: all cows or all black cows).
We can compare generalisation scopes only when the subject of one is a subset of the subject of the other.
It can sometimes be important to adjust the scope of a generalisation, making it either narrower or wider.
Usually, in reconstructing arguments, we have to narrow them.
By narrowing the generalisation, the issue is defined more exactly.
When reconstructing arguments, we should take care not to employ a hard generalisation that is wider in scope than we need if there is anything doubtful about the wider one that could be eliminated by employing a narrower one.
If a narrower (but hard) generalisation will suffice for constructing an argument for the desired conclusion, when we should employ the narrower one.
This is not to say we should always choose narrow generalisations whenever possible!
In some cases there is not natural word or phrase for the class of cases we wish to generalise about. In such cases we have to reduce the scope of a generalisation by explicitly accepting a certain class of what would otherwise be counterexamples.
Practical conclusions: a conclusion that enjoins or commends a particular action.
What the argument says is that doing one thing in necessary if a certain desirable outcome or end is to be achieved.
Practical reasoning: means-end reasoning.
Based upon two sorts of considerations:
But:
In reconstructing arguments, we need to incorporate both of the points above as premises.
Practical reasoning involves a weighing of one value (the value of the desired result) against another value (the negative value of the cost of the envisaged means of bringing about the desired result).
Almost any action could, in principle, be rationalised by practical reason.
In cases when the argument must be represented as inductive, we have to juggle three factors
There are only rough estimates. No one assumes that anyone can specify exactly how bad or how good outcomes would be relative to each other.
Expected value: for each possible outcome of the action, you multiply the probability of the outcome by its value (its cost or benefit, as the case may be). Then you add these figures together.
When given a range of possible actions, one should do whatever maximises expected value.
There is a certain limit to the application of expected value calculations: the expected value of a proposed action tells us whether or not it would be rational to do something, unless it is overridden by the existence of rights or moral rules.
In an explanation, the truth-value of that proposition is not in question.
Use the word ‘cause’ or ‘because’ in the conclusion.
Abduction
The generalisations appealed to in arguments of this kind are often soft rather than hard, and more generally the arguments can be inductive rather than deductive.
Abductive argument: an inductive explanation.
The best and most likely explanation.
Causal statements often appear as generalisations about types of events or states of affairs.
The word ‘cause’ does not always, or even typically, indicate hard generalisation of this kind.
In order to infer a causal relationship from a correlation between X and Y, we need to know that the correlation holds, or would hold, even when other possible causes of Y are absent or were present.
Where an argument contains a conditional among its premises, we have, in order to infer the consequent of the conditional, to write down its antecedent as a separate premise.
If P2 is a conditional whose antecedent is P1, instead of rewriting P1 out in full, we may abbreviate its simply as ‘P1’.
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Introducing Arguments - summary of chapter 1 of Critical thinking: A concise guide by Bowell & Kemp (4th edition)
Critical thinking
Chapter 1
Introducing Arguments
To attempt to persuade by giving good reasons is to give an argument.
Not all attempts to persuade (using language) are attempts to persuade by argument.
some are attempts to persuade by means of rhetorical devices
Rhetoric: any verbal or written attempt to persuade someone to believe, desire or do something that does not attempt to give good reasons for the belief, desire or action, but attempts to motivate that belief, desire or action solely through the power of the words used.
An attempt to persuade by argument is an attempt to provide you with reasons for believing a claim, desiring something or doing something.
Arguments appeal to your critical faculties, your reason.
Rhetoric tends to rely on the persuasive power of certain words and verbal techniques to influence your beliefs, desires and actions by appeal to your desires, fears and other feelings.
threats and bribes are arguments (not rhetorics), for they give a reason to do something
Rhetorical techniques can be manipulative and coercive. Their use should generally be avoided by those who aspire to think critically and to persuade by reason.
When analysing attempts to persuade, we have to perform three tasks:
When we put forward an argument we are either advancing an opinion or recommending an action.
In either case we give a number of claims intended to support the claim or the recommendation.
These two types of argument can be collapsed into one.
All arguments can be understood as attempting to provide reasons for thinking that some claim is true (it states how things really are).
To say that a claim is true is to say that what is claimed is how things actually are.
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.....read more Language and rhetoric - summary of chapter 2 of Critical thinking: A concise guide by Bowell & Kemp (4th edition)
Critical thinking
Chapter 2
Language and rhetoric
Once we’ve determined that a text or a speech contains an attempt to persuade by argument, the remainder of argument-reconstruction is largely a matter of interpreting the speech or text as accurately as possible.
Ambiguity
Ambiguity can be used, often deliberately, to obfuscate the content of an argument or rhetorically to obscure the persuaders true point.
A sentence is ambiguous in a given context when there is more than one possible way of interpreting it in that context.
There are two types of ambiguity:
Lexical ambiguity
Lexical ambiguity: a property of individual words and phrases that occurs when the word or phrase has more than one meaning.
Extension: the set or group of things to which an expression applies.
(for example, the extension of the word ‘cow’ are all the cows in the world).
An ambiguous word or phrase has two or more separate and different extensions.
Ambiguous words and phrases can bring their ambiguity into sentences, making those sentences capable of having more than one possible interpretation.
Words that are potentially lexically ambiguous are not necessarily ambiguous in every context.
When interpreting sentences that are lexically ambiguous, we have to focus on the context in which they are written or said and the consequent probability of each of the possible interpretations being the correct one.
Syntactic ambiguity
Syntactic ambiguity: when the arrangement of words in a sentence is such that the sentence could be understood in more than one way.
Vagueness
The meaning of a word or expression is vague if it is indefinite or if it is uncertain what is conveyed by the word in the context under consideration.
Sometimes, someone aware of the weakness of their own position will deliberately leave their meaning vague in order to camouflage that weakness and to evoke strong feelings of approval or disapproval in their readers or listeners.
Words can also have a clear meaning, but which have an indefinitely demarcated extension.
(like colors)
Primary and secondary connotation
The rich secondary connotation (bijbetekenis) of some words provides a further source of vagueness.
Primary connotation: a given thing falls within a word’s extension if,
.....read more Logic: deductive validity - summary of chapter 3 of Critical thinking: A concise guide by Bowell & Kemp (4th edition)
Wst-r
Chapter 3
Logic: deductive validity
Argument reconstruction: the representation of arguments in standard form, so as to give us a clear and comprehensive view of them.
Argument assessment: the determination of whether or not arguments provide good reasons for accepting their conclusions.
An argument is a system of propositions.
Propositions: a set of premises advanced in support of a conclusion.
People succeed in expressing the propositions they have in mind in varying degrees of clarity. An argument may depend upon premises that the arguer does not state at all, but which he or she is implicitly assuming.
Since the purpose of argument-reconstruction is to determine exactly what argument has been given, part of the task is to clarify what the arguer actually said, and to supplement what the arguer actually said (to make explicit what was merely implicit in the arguer’s statements).
Argument-reconstruction is essentially a task of interpretation.
The principle of charity.
In such facts pertaining to the context in which the argument is given, together with the specific words used by the person, will constitute the total evidence you have for reconstructing the argument.
If, in the third case, you have to chose what representation of the argument is true, it depends on your purpose.
The practice of argument-reconstruction - summary of chapter 5 of Critical thinking: A concise guide by Bowell & Kemp (4th edition)
Critical thinking
Chapter 5
The practice of argument-reconstruction
The first step in reconstructing an argument is to make a list of the argument’s premises and conclusion as concisely and clearly as possible.
Making such a list is only the first step towards a complete reconstruction.
Expressive epithet: terms used to refer to some person, group or other entity but that characterize the entity referred to for rhetorical purposes.
When reconstructing arguments we should strive to display the logical relationships in an argument in the simplest, clearest and most familiar ways possible.
This is not always possible, and doing it will sometimes distract us from other points we are trying to make.
Not only do actual statements of arguments typically include a lot of material that is inessential to the argument, they often exclude some of what is essential to the argument.
Our task is to make the argument fully explicit.
A proposition is implicit: the proposition is part of the argument intended by the arguer but it has not actually been stated by the arguer.
To make a proposition explicit: to state it.
Issues in argument assessment - summary of chapter 6 of Critical thinking: A concise guide by Bowell & Kemp (4th edition)
Critical thinking
Chapter 6
Issues in argument assessment
The role of an argument is to give us reasons for accepting its conclusion as true.
The aim is to give an argument by which the intended audience is ought to be persuaded.
We cannot always tell whether or not the argument is sound.
Sound arguments must have true premises.
Since we do not always know which propositions are true and which false, we cannot always tell whether an argument is sound or not.
To say that an inductively forceful argument is defeated for a person: the person reasonably believes the premises, but, nevertheless, reasonably rejects the conclusion.
(They have, for example, extra information).
An inductively forceful argument whose premises you have reason to accept is rationally persuasive only if your total evidence does not defeat the argument for you.
To say that an argument is rationally persuasive for a person:
Rationally unpersuasive argument: an argument that is deductively sound and valid, but gets you no closer to knowing the truth-value of the conclusion.
Rational persuasiveness is doubly relative.
Since people are in different states of information at different times, an argument may be rationally persuasive for one person, but not for another.
Seven points to bear in mind as regards rational persuasiveness:
1 It is not possible for the conclusion of a deductively valid argument to be defeated by a person’s total evidence. This is only possible for inductively forceful arguments.
2 Rational persuasiveness is not part of the definition that the argument be sound (either deductively or inductively).
Pseudo-reasoning - summary of chapter 7 of Critical thinking: A concise guide by Bowell & Kemp (4th edition)
Critical thinking
Chapter 7
Pseudo-reasoning
Fallacies count as arguments in the sense that they fit our definition of an argument. They consist of a set of propositions, some of which premises, one of which is a conclusion. But, one way or another, they are bad arguments.
A fallacy: a mistake in reasoning.
One commits a fallacy when the reasons advanced or accepted in support of a claim fail to justify its acceptance.
A fallacy can be committed either when one is deciding whether to accept a claim on the basis of a fallacious argument with which one has been presented or when one is presented the fallacious argument oneself.
A fallacious argument or inference: one in which there is an inappropriate connection between premises and conclusion.
Almost all fallacies fall under one of the following two types:
The majority of fallacies that we encounter in everyday texts and speech are substantive fallacies.
A fallacious argument can have true or false premises.
Simply having false premises does not make an argument fallacious.
Nor does having true premises guarantee that an argument is not fallacious.
A proposition accepted on the basis of a fallacious argument may turn out to be true as a matter of actual fact.
The best way to become acquainted with the different types of fallacies is to practise identifying and analysing them.
As they are attempts to persuade by argument, you need to reconstruct them in standard form and then use techniques of argument analyses and assessment to demonstrate the ways in which they are fallacious.
Many types of fallacious argument are effective as rhetorical ploys.
Formal fallacies
Formal fallacies: patterns of argument whose reasoning makes purely logical mistakes.
Each type of fallacy constitutes an invalid argument.
The fallacies will be recognized by the presence of the particular invalid pattern.
Affirming the consequent of a conditional
Affirming the consequent for short.
This occurs when we argue from the conditional premise that if P (the antecedent), then Q (the consequent) together with the premise that Q to the conclusion that P.
P1) If P then Q
P2) Q
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