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).
3 An attempt at persuasion by argument is an attempt at rational persuasion, as opposed to other kinds of persuasion, which do not appeal to your reason.
4 Rational persuasiveness is a matter of degree, it is not all-or-nothing.
5 ‘Rationally persuasive’ does not mean merely ‘persuasive’ or ‘convincing’. A rationally persuasive argument may fail to persuade anyone. Whether or not an argument is rationally persuasive for you does not depend upon whether you think it is.
An argument may be rationally persuasive for you even though you are not persuaded by it. There are cases you ought to be persuaded by an argument, but you are not.
Likewise, there are cases where you are persuaded or convinced by an argument, but where you should not be, because the argument is not rationally persuasive for you.
6 Judgments about rational persuasiveness very frequently depend on estimates of the legitimacy of the authority behind certain propositions.
7 In saying that an argument is rationally persuasive for a person only if the person reasonably believes the premises, we are not requiring that the person have at his or her disposal further arguments with those premises as conclusions.
What we are requiring is that the person be justified in accepting the premises.
Justification is a wider concept than rational persuasiveness: if one has a rationally persuasive argument for a proposition then one is justified in accepting it, but one may be justified in accepting it by means other than argument.
If you can think of ways in which the premises would be true but the conclusion false, then you must determine to what degree, if any, the argument is inductively forceful.
What you do here is to imagine various situations in which all the premises are true.
Of these situations, which are more likely? The ones in which the conclusion is true, or the ones in which it is false?
If the situations in which the conclusion is true would be more likely than those in which it is false, then the argument is inductively forceful, if not, it is not.
If it is forceful, it remains only to specify the degree to which it is so.
Whenever we find that an argument is not valid, we should always ask whether there are premises that:
Arguments with conditionals or generalisations as conclusions, conditional proof
What a conditional asserts, roughly, is a certain relation between the antecedent and the consequent. That if the antecedent is true, then so the consequent is.
The question:
If the premises of the argument were true, then would this purported relationship hold?
To answer that question, we suppose not only that the premises of the argument are true, but that the antecedent of the argument’s conclusion is also true.
Then we want to know whether, under all these suppositions, the consequent of the argument’s conclusion would also have to be true.
If that is so, then that conditional proposition does follow from the premises.
In order to determine P → Q follows from some premises, we ask whether Q follows from those premises together with P.
This is conditional proof.
It provides a simplified means of proving a conditional.
Supposing the conclusion is false
Another way to assess the validity of an argument is to suppose the premises are true but the conclusion is false. If we can see that this is impossible, then, according to the definition of validity, the argument is valid. If we can see that this is possible, then we know that the argument is invalid.
This method can be used on any argument.
You can give a counterexample for an argument by giving another argument in the same form.
And make everything explicit.
If an argument is unsound due to an implicitly assumed but false generalisation, first make explicit the assumed generalisation in such a way that the argument becomes deductively valid (or inductively forceful). Then find a true premise and false conclusion that are suitably analogous to the premise and conclusion of the original argument, and substitute them.
Sometimes an argument will contain a premise that no one would say can be known with certainty.
Where an argument is inductively forceful, the person who says ‘who is to say’ that the conclusion is true is either repeating what nobody doubts (that the argument is not deductively valid) or expressing a seemingly unreasonable scepticism, like a person who refuses to believe that past observation supports the hypothesis that spring will follow winter.
In order effectively to criticise an argument, in order to engage with it, one must either:
Merely pointing out that a term occurring in the argument is vague or value-laden is not sufficient.
Certainly remarking the presence of vagueness is not sufficient.
Engaging with the argument II: don’t merely label the position
Argument analysis: a two-stage process, comprising first the reconstruction, then the assessment of the argument.
When the analysis of an argument is undertaken, you may sometimes want to produce a piece of written work that summarises the analysis you have made.
This should consists of:
He commentary is simply a written piece of work that covers the following points (either all of them, or as many as seems relevant in the particular case):
1 A general discussion of the argument, explaining, as appropriate:
2 A discussion of how and why the standard-form reconstruction was derived as it was, focusing especially on any problems encountered in the process. In particular:
In general, this section should ideally include everything necessary to justify the given reconstruction.
3 A discussion of the validity or degree of inductive force of the argument.
4 If the argument is either valid or inductively forceful, a discussion and verdict concerning the truth-values of the premises. This will amount to a verdict regarding the soundness of the argument. It should be explained in detail which premises are most debatable and why.
5 In the case of an inductively sound argument, you should say whether or not the argument is defeated for you.
JoHo can really use your help! Check out the various student jobs here that match your studies, improve your competencies, strengthen your CV and contribute to a more tolerant world
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.
A
.....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
---------------------
Everything you need for the course WSRt of the second year of Psychology at the Uva
This magazine contains all the summaries you need for the course WSRt at the second year of psychology at the Uva.
JoHo kan jouw hulp goed gebruiken! Check hier de diverse studentenbanen die aansluiten bij je studie, je competenties verbeteren, je cv versterken en een bijdrage leveren aan een tolerantere wereld
There are several ways to navigate the large amount of summaries, study notes en practice exams on JoHo WorldSupporter.
Do you want to share your summaries with JoHo WorldSupporter and its visitors?
Field of study
Add new contribution