Modes of reasoning Questions
lazy808
Lecture16FallacieswithInsufficientPremises.ppt“Reasoning About Social Issues”
Petrenko Anton, PhD
Hours: By appointment (Monday 11:30-12:30)
E-Mail: [email protected]
AP/MODR1730 D
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This lecture will introduce students to fallacies in argumentation. This lecture will focus on fallacies with insufficient or unacceptible premises.
Lecture Objectives
Slippery slope
False analogy
False dichotomy (False Dilemma)
False Cause (Post Hoc)
Begging the Question
Hasty Generalization
Loaded Presupposition
Self-evident Truth
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Insufficient or unacceptable premises: Hasty Generalization
The fallacy of hasty generalization is committed when we draw the conclusion about the whole group (population) based on inadequate (small or unrepresentative) observation of the part of the sample of the group.
The French are snobby and rude. Remember those two high-and-mighty guys with really bad manners. They are French. I rest my case.
You should buy a Dell computer. They are great. I bought one last year, and it has given me nothing but flawless performance.
In Hasty Generalizations, the premises are relevant to the conclusion, but they are insufficient (also unacceptable because insufficient).
The sample is either too small or unrepresentative of the population.
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Insufficient or unacceptable premises: Begging the Question
The fallacy of begging the question (arguing in a circle) is committed when one attempts to establish a conclusion in an argument by using the conclusion as a premise (instead of proving the conclusion, one assumes it).
God exists. We know it because the Bible says so, and we should believe the Bible because God says so.
The Bible says so.
Therefore, God exists
The Bible is to be believed because God wrote it.
Premise 2 can only be true if we already know that God exists. But this is only established in the conclusion.
To allow every man unbounded freedom of speech must always be, on the whole, advantageous to the state; for it is highly conducive to the interests of the community that each individual should enjoy a liberty, perfectly unlimited, of expressing his sentiments.
Here, the premise is just the conclusion restated in a different form (p, therefore p).
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Insufficient or unacceptable premises: False cause
The fallacy of false cause is committed when one infers causal connection without having established the all the conditions of a causal connection.
Ever since the capital punishment was abolished, the crime rate has been increasing. The abolishment of capital punishment is the reason for there is more crime.
This is an example of a Post Hoc fallacy (‘post hoc ergo propter hoc’ or after this, therefore because of this). One thing happening after another does not mean that one caused the other—post hoc fallacy makes this mistake.
A newspaper report of a scientific research study: Psychologists have discovered that most male scientists make their major discoveries in their late twenties and thirties, which is also the period when their sexual interest is at its peak. Therefore, the psychologists concluded, male scientists strive to achieve to attract the attention of women. Scientific inquiry is driven by sexual desire.
This is an example of a correlation without covariance. There could be a third factor as a cause responsible for both discoveries and sexual interest—age.
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Insufficient or unacceptable premises: False dichotomy
The fallacy of false dichotomy (or false dilemma) when one presents two alternatives (as if there are only two possible) and forces a choice between the two (as if they are mutually exclusive).
Either you are in favor of state support for the arts, or you are an uncultured tug. You are not in favor of the state support for the arts. Therefore, you are an uncultured thug.
Here, one reaches the conclusion (by elimination) by forcing a choice between only two options. But this works only if not other options are possible. But it is possible to be both cultured, and not in favor of state support because you think money can be better spend elsewhere. The argument fails because it does not consider other options.
Either those lights you saw were alien spacecraft (UFO), or you were hallucinating. You were not hallucinating. Therefore, those lights were alien spacecraft.
…or it could be a weather balloon, a meteor, a lightening, a commercial airliner…
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Insufficient or unacceptable premises: False analogy
The fallacy of false analogy is committed when a person draws a conclusion on the basis of an inappropriate comparison between two things.
Dogs are warm-blooded, nurse their young, and give birth to puppies. Humans are warm-blooded, and nurse their young. Therefore, humans give birth to puppies. (David Hume, illustrating why Paley’s watch argument is a faulty analogy)
Nature is a book open to everyone to read. If we do not understand it, it is simply
because we have not read it carefully enough. And like a book, nature requires an
author. Its author is God.
One commits the fallacy either when the similar properties are irrelevant to the conclusion (the inferred property) or when they are too few when compared to dissimilarities.
This analogy fails because the books and nature are not similar in relevant respects: books are messages, which require authors; natural laws are not messages—they don’t require authors.
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Insufficient or unacceptable premises: Slippery slope
The fallacy of slippery slope is committed when a person argues, without good reason, that taking a particular step will inevitably lead to further (undesirable) steps.
All Canadians should oppose gay marriage. Because if gay marriage is allowed, then before you know it, anything goes—polygamy, incest, marrying animals... who knows....
These type of arguments are fallacious not only because the consequences are not certain, but also because there is no good reason to believe that they will occur.
Americans must not lose war in Vietnam. If South Vietnam falls to the communists, then Thailand will fall to them. If Thailand falls, then South Korea will fall to them. Before you know it, all of South Asia will be under communists.
The argument is fallacious because it gives no relevant evidence that effects will occur. There are many things that intervene between Vietnam and the other countries mentioned. Americans lost, but dominos did not fall as predicted.
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Insufficient or unacceptable premises: Self-evident Truth
The fallacy of self-evident truth is committed when one presents a contentious position, which is in need of defense, as a self-evident truth that does not need a defense.
Surely, one can’t doubt that men have better self-control than women. This means that a men is better suited for positions requiring cool head under stress.
By presenting a contentious (or one not well established) premise as self-evident, the person attempts to avoid the requirement to justify it.
Surely…
It is obvious that…
No doubt…
No one can deny
It is important to keep in mind that such claims commit the fallacy only if no evidence is being provided to substantiate the claim, and the claim is not well established as one attempts to imply.
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Insufficient or unacceptable premises: Loaded Presupposition
The fallacy of loaded presupposition is committed when a person makes a statement or a question (aka complex or leading question), which can’t be answered without granting the truth of the statement it presupposes.
Have you stopped drinking vodka in the morning?
Accepting the claim or answering the leading question commits one to accepting the undefended presupposition within it.
Are you still gambling on Sundays?
Will you be taking 8:40 or 9: 10 train?
Why are children of divorced parents are less emotionally stable than those raised in unbroken homes?
The opposition’s treacherous policy must be rejected. It will lead us into a fiscal crisis.
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Neutralizing Fallacies
1. Summarize the argument where it occurs
2. Name the fallacy
3. Give the criteria for committing the fallacy
4. Explain how the fallacy happens in the argument
5. Challenge the fallacy
Either you like hokey, or you are gay
You don’t like hokey
You are gay
False Dichotomy
False Dichotomy is committed when options are artificially limited (others are ignored)
Only two options are given: a) gay or b) like hokey
Not exclusive: one can be gay and like hokey or not gay and like hokey (maybe the person finds it dull or too violent)
Neutralizing fallacies allows to have a systematic approach to identifying and analyzing fallacious arguments: summarize the argument, name the fallacy and its criteria, and show how the argument fits them. Show why argument fails.
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