A Short Catalog of Informal Fallacies
(The general grouping of the fallacies below, along with some of the examples, are from Patrick Hurley, A Concise Introduction to Logic, 4th ed., Wadsworth, 1982)
One general grouping of informal fallacies is as follows:
1. Appeal to force.
In this informal fallacy the arguer makes a claim, then threatens his opponent with harm if they dont accept that claim. The threat could be a physical threat, such as when one threatens another with violence if they dont accept the claim p osed. The threat could also be a psychological one, such as threatening to make public some embarrassing information about the arguers opponent. Some examples are as follows.
2. Appeal to the people (ad populum)
In this fallacy the arguer uses common desires such as the need to be appreciated, to fit in, to be admired, etc. to persuade the listener to believe a conclusion. Such a fallacy may proceed directly, as when a speaker excites emotion in a crowd in ord er to take advantage of the common tendency of excited crowds to accept (often dubious) claims without much justification. An appeal to the people may also proceed indirectly, in the sense that the arguer appeals to ones desired role as part of the crowd (rather than appealing to the crowd as a whole). Two examples of the indirect approach are given below.
2a. Bandwagon argument
In a bandwagon argument the arguer uses the common desire to fit in with the crowd in order to make his conclusion more likely to be accepted. For example,
2b. Appeal to Vanity
In this sort of appeal to the people the arguer uses the desire to be associated with someone or something that is admired or loved in order to get the listener to accept their claim. For example,
3. Argument against the person (ad hominem)
In an ad Hominem argument, instead of criticizing his opponents position or argument the arguer just attacks his opponent himself. There are three kinds of ad hominem arguments: the ad hominem abusive, the ad hominem circumst antial, and the tu quoque "you too" argument.
3a. Ad hominem abusive
In this form of the ad hominem argument the arguer abuses his opponent verbally. For example,
3b. Ad hominem circumstantial
In this form of the ad hominem argument the arguer points out some circumstances that affect his opponent in such a way that his argument or position gets discredited. Such arguments are very common; for example,
In the above passage the arguer never considers Gates argument (whatever that might be), but instead just points out that Gates is the CEO of Microsoft. The arguer needs to be addressing Gates argument, not any interesting properties of Gates himself. The reason is that facts about Bill Gates himself have little or nothing to do with the strength or validity of Gates argument.
3c. Tu Quoque
In this form of the ad hominem argument an arguer makes his opponent appear hypocritical by pointing out something about the person hes arguing against. For example,
Notice that the arguer in the above passage merely points out something about his mother herself that makes her position on drug use appear hypocritical. Whether or not ones mother used to use drugs (or even still does) has nothing to do with whatever her argument might be against the use of them.
4. Straw man (or straw person)
In this fallacy the arguer distorts his opponents argument or position to make it appear weaker than it really is. The arguer then attacks the distorted version, making a conclusion against the original argument or position. For instance,< /P>
Jones position gets distorted into one that endorses atheism (which clearly isnt entailed by the claim that prayer in public schools is improper). The arguer then finds fault with atheism the distorted version of Jones real position), and concludes that Jones position is bad. Of course, attacking the distorted version of Jones position is irrelevant to the merit of Jones actual view.
5. Missing the point
When an arguer misses the point he puts forth a set of premises, but then draws a conclusion considerably different from one supported by those premises. Here is an example:
There may be a number of different conclusions one might draw given the premise concerning Milwaukees increase in the crime rate, but reinstatement of the death penalty is hardly supported by that premise.
6. Red herring
A red herring fallacy occurs when an arguer distracts the reader or listener with some claim that is irrelevant to the issue at hand. The arguer then makes a conclusion concerning the irrelevant issue, or draws no conclusion at all. For instance,
Here the arguer does nothing to address the issue of the dangers of nuclear power, but instead changes the subject to the danger of electricity. If theres even an argument at all here, it certainly has nothing to do with the original issue.
1. Appeal to authority
In an appeal to authority, the arguer uses the testimony of an expert as a reason to believe his conclusion. There are arguments of this kind that arent fallacious, as when the expert in question is an expert on the issue the arguer is making a c onclusion about. For instance, when someone claims they have cancer, and give as reason for their belief the prognosis of a doctor who is a specialist in cancer treatment, the argument isnt fallacious. However, if the expert isnt an expert on the topic in question, the argument often is fallacious. For instance,
My dentist is surely a good judge of matters pertaining to dentistry. However, without some further evidence of his knowledge of the CCU football program (among other things) the argument given is a fallacious appeal to authority.
2. Hasty generalization
This fallacy occurs when an arguer draws an inductive inference on the basis of a sample size that is too small. For instance,
It seems pretty clear that two instances of flat Fat Tire pints isnt enough evidence to warrant the inference to the next one being flat.
3. Slippery slope
A slippery slope fallacy occurs when an arguer makes a number of weak inductive inferences (often involving purported causal connections) to a conclusion that is undesirable. The arguer then concludes that the initial step in the chain of inferences sh ouldnt be accepted. For example,
In the letter there are a number of inductive inferences made concerning causal connections (such as between not teaching the Ten Commandments and not teaching all history regarding Christianity) on the way to the conclusion that if one accepts the ACL Us initial position (opposing the display of the Ten Commandments), then the end result will be removing history from the curriculum of public schools. As such an end result seems undesirable it is tempting to reject the initial step that the ACLU p roposes. However, as each of the inductive inferences in the argument are weak, its ridiculous to suppose that the removal of history from the curriculum really will ultimately result from not allowing the Ten Commandments to be displayed.
1. Begging the question
There are (at least) two main ways for an argument to beg the question: (1) arguing in a circle by presuming in the premises the truth of the conclusion, and (2) presuming the truth of an important but controversial premise. An example of the first sor t of begging the question is as follows.
Its pretty obvious that if the Bible is Gods word, then God exists (or at least did exist). However, since the argument also claims that the Bible really is Gods word, it presumes that God exists in order to p urportedly prove that God exists. This is circular. Here is an example of the second sort of begging the question.
The argument presumes the truth of a premise that isnt stated, namely that abortion is murder. As this premise is far from obvious, and the arguer doesnt even mention it (much less give it a defense), the argument begs the question.
2. Complex question
A complex question combines two or more distinct questions into a single one, thus presuming the truth of some claim. All of the following questions are complex questions.
Here no matter how one answers, one seems to admit to using drugs at some point. Thus the questioner makes an unwarranted presumption that whoever is answering the question is using drugs.
A similar sort of move is made in the latter two complex questions.
3. False Dichotomy
A false dichotomy fallacy is made when the arguer presumes there are only two options available and rejects one option in favor of the other. However, it turns out that there are really more options available than the two given by the arguer. For insta nce, the familiar claim
commits a false dichotomy. After all, there are other options than loving the system as it is and leaving the country. Such arguments can be more subtle, however. Consider the following argument that one might have made prior to the Senate's vote to remove President Clinton from office:
This argument might be improved with some more premises, but as stated it presumes that there are only two options with regard to the punishment of the president for his behavior. However, as it seems there are other options with regard to punishme nt (censure, his current punishment in the form of public humiliation, etc.) the argument as stated commits a false dichotomy fallacy.
An equivocation is made when a word is used in more than one meaning within the same argument without distinguishing between the different meanings. For example,
The phrase public interest is used equivocally in the above argument. In one premise it is used in the sense of what the public has a political interest in, and in another it is used in a sense of curiosity.
A composition fallacy occurs when an arguer inappropriately projects a property of the parts of something onto the whole. For example,
A group of good athletes might not perform well together (among other things), so the inference is a weak one.
A division fallacy is the reverse of a composition fallacy. A division fallacy occurs when an arguer inappropriately projects a property of the whole onto one or some of the parts. For example,