F05SENG311.Logical Arguments
From Craig
Logical arguments as a basis for assessing moral arguments
This page represents a summary of the text, Logical Self Defense by R Johnson and J. Blair, McGraw-Hill Ryerson, 1983.
Arguments vs. Opinion
- Opinion : A judgement about a particular idea which may not be presented with reasons or grounds
- When people have a difference of opinions, they will often try to sort those differences out
- This may lead to an argument
- Argument: a collection of claims (or statements) whose purpose is to lay out a route which leads from the acceptance of some claims (premises) to the acceptance of some other target claim (the conclusion). (Logical Self Defense, R. Johnson & J. Blair, 1983).
In order to evaluate an argument, we must first extract the argument:
- Is there an argument?
- If so, what are its constituent parts?
Arguments and Critical Thinking
- Critical thinking: a range of analytical skills which can be used to distinguish factual claims from opinions and value judgements.
- The careful deliberate determination of whether we should accept, reject, or suspend judgement about a claim.
- Claims or statements are used with a logical argument
Arguments have three important characteristics:
- a form of reasoning
- is comprised of claims
- Aims to establish a conclusion based on one or more claims
A strong argument is one in where the route taken from the premises to the conclusion is solid. A poor argument is one where the route taken is filled with detours, deadends, and roadblocks: it is filled with fallacies.
Three requirements of a strong argument:
- The premises must be relevant to the conclusion
- The premises must provide sufficient support for the conclusion
- The premises must be acceptable
Any argument which fails to satisfy all three is a fallacious argument.
Fallacies
- Fallacy: Faulty reasoning (Note: does not mean false statement)
- A violation of one of the criteria which govern good arguments
Irrelevant Reason
- M has put forth Q, R, S ... as premises for T
- In conjunction with R, S, ... Q is irrelevant to T
Note: Relevance (or lack thereof) can be difficult to show. Relevance is not specific to a particular premise (unlike truth). It requires that an individual premise is taken together with other items of evidence or information.
Hasty Conclusion
- M represents that Q, R, S are sufficient support for conclusion T
- Q, R, S taken together are not sufficient support for T because:
- they do not supply sufficiently systematically gathered evidence
- they do not supply a sufficient sample of the various relevant kinds of evidence
- they ignore the presence or possibility of contradictory evidence
Often accompanied by anecdotal evidence and conjecture
Problematic Premise
- M asserts Q as support for R
- M presents no evidence for Q
- In the circumstances in which the argument is presented, there is some specific reason why Q should not be accepted without a defence.
This type of fallacy ususally involves missing some sort of evidence or directly supressing evidence which would detract or contradict the conclusion.
Begging the question
- Q is offered in an argument as a premise to support R
- Q asserts the same proposition as R or Q is acceptable only if R has already been accepted.
This reflects a circular argument. To support a conclusion, premises must be different from that conclusion.
Inconsistency
- Q is a premise for M's argument for T
- Q is inconsistent with another premise or assertion made by M
A series of premises are set up in support of T. However, two of the premises relate to each other such that when one is true, the other must be false.
Strawman
- M attributes the argument Q to N
- N's position is not Q, but instead R
- M criticizes Q as though it was the position held by N
Misrepresenting your opponents view with an argument which you can easily demolish.
Ad Hominem
- M responds to Q, a position taken by N, by attacking N rather than Q
- The attack on N is not relevant to the assessment of Q
It is possible for an argument to have credibility even when the credibility of the person suggesting it is in question.
Guilt By Association
- M attacks N or N's position Q on the basis of some alleged association between N or Q and some other person, group or belief(s)
- Either the alleged association doesn't exist at all or the alleged association does not provide relevant or sufficient support for M's criticisms
One of the most common occurences of this fallacy is by associating someone with the Nazis because we all know the Nazis were bad.
Red Herring
- In an adversary context, N has made a claim Q that is or implies a criticism of a position that M holds or identifies with.
- M responds to Q by asserting R which introduces an issue which is not relevant to the acceptability of Q and thereby instigates a shift of focus away from the acceptability of Q
In an attempt to discredit some claim, the person making the claim introduces a flood of information which is not relevant to the original claim.
Faulty Analogy
- an analogy is offered in support of an argument
- The two things being compared are not similar in the respect required to support the conclusion
Improper appeal to practice
- M defends action X against criticism by arguing that X is widely practiced or is a custom or traditional practice
- The existence of the practice of X is either not relevant or not sufficient to justify M's defence of X
"Everybody does it!"
Loaded term
- M labels something X in a way that is either debatable or false
- M uses that classification of X without defence or support for some conclusion Q
Improper appeal to authority
- M appeals (directly or indirectly) to the authority of N supporting the claim Q (which belongs to domain of assertions, S)
- S is not a domain in which authoritative knowledge can, or does, exist
- N is not an authority in the matters of domain S
- Although S is in general a domain of knowledge, authorities of domain S lack consensus that such claims as Q are true
- N is not identified sufficiently to enable one to check N's credentials
Popularity
- M claims or implies that Q is true (or false) and offers as proof that Q is widely accepted (or not)
- The popularity (or lack thereof) of Q is not an adequate reason for accepting or rejecting Q
Slippery Slope
- M claims that if W is permitted, it will lead to X, X will lead to Y, and so on to Z
- M holds that Z is undesirable and therefore W should not be permitted
- At least one of the steps in the chain is unsupported and open to challenge.
Constructing Arguments
In order to be able to successfully critique someone else's argument, you must have the capability of constructing an argument. If you cannot support your own criticisms of someone else's arguments, your criticisms won't be accepted.
Before you can construct an argument (or a piece of software for that matter) you have to understand its purpose. The typical purpose of an argument is to persuade but they can be used to support/augment what the audience already believes. Arguments can also be used as a form of inquiry. In this case, the person conducting the inquiry test various alternate theses by seeing whether good arguments can be found to support those theses.
Regardless of the purpose of the argument, its existence presupposes 2 assumptions: 1) there must be some doubt about the conclusion (there is no point to arguing something which is self-evident); and 2) there must be at least 2 persons involved. The second assumption implies that there is an audience in mind and this is relevant to how you construct your argument.
- Identify the Problem, Question or Issue
- Clearly understand the problem, question or issue. You must be able to state why it is controversial enough to warrant an argument.
- Making your position clear
- You should be able to state your position in a single sentence or clause which begins with the word "that"
- "My position is that ..."
- My position is that Java is a better programming language than C++
- "My position is that ..."
- A common mistake is to combine one's position with an argument or fragment of an argument.
- My position is that Java is a better programming language than C++ because it has better support for Object-Oriented principles
- By combining the position and the argument (or fragment) it becomes difficult to defend
- Is the objection an objection to the argument or an objection of the position
- Another common mistake is to state two positions together when they require separate defences
- It is acceptable to have two or more distinct positions related to a single issue
- You should be able to state your position in a single sentence or clause which begins with the word "that"
- Presenting your argument
- State your strongest arguments
- If you have more than one argument, be sure to keep your arguments separate
- If one argument is refuted, another may still remain sound
- State your argument as completely as you can. Specify all of the steps
- State your strongest arguments
- Defend your argument
- Your arguments must meet the same standards as everyone else's arguments
- relevance, acceptability, sufficiency
- Your arguments must be fallacy free
- Consider what objections your opponents might consider against your arguments
- Your arguments must meet the same standards as everyone else's arguments
- Considering objections to your position
- Arguments against your position should be stated fairly and fully (or you risk setting up a straw man)
- These arguments will have as their conclusion that either your conclusion is false or that another proposition which, if true, would be incompatible with your conclusion.
