Definition of "Fallacy"
Tip: Outline the Argument.
Novelty, Appeal to
Poisoning the Well
Popularity, Appeal to
Quoting Out of Context
Tradition, Appeal to
Greetings! Want to better your ability to detect errors in reasoning, so you can avoid them in your arguments and expose them in your opponents' arguments? This page should help with both ends, by discussing various fallacies that are commonly commited, whether they occur in everyday language, advertisments, or especially apologetic debates.
There are several ways an argument can go wrong. For instance, one of the claims can turn out to be false, or at least not supported by the evidence, and therefore doesn't support the conclusion. Or, there could be a flaw in the structure of the argument, so that even if the premises are true, they do not support the conclusion. Our primary interest here is in the latter type of failure.
A fallacy is typically defined as, "A mistake in reasoning; a type of argument that may seem to be correct, but that proves upon examination not to be so" (Copi, 632). What we are talking about are types, or categories, of errors in reasoning, not the errors themselves. For instance, consider this hypothetical discussion:
Paul comments postively about universal healthcare.In this case, Bob is casting doubt on Paul's case by attacking his character. We call this kind of fallacy argumentum ad hominem, which we discuss in more detail below. What we readily observe is that the same fallacy can be committed with different terms. Hence:
Bob responds, "Don't take Paul's assertions seriously, because he picks his nose." [The implication being, Paul is wrong]
Bob critiques universal healthcare.This is also an argumentum ad hominem.
Paul responds, "What does Bob know, he hates nose pickers."
It should be noted that the problem here is not in the word structure of the argument, but the "thought" structure, so to speak. Because of this, I find it easier to find fallacies by outling the argument at hand. This will include detailing implied propositions, if any. We can outline the first ad hominem above as:
1. It is Paul's claim that universal healthcare is good.Often you can just "see," intuitively, why the reasoning is fallacious.
2. Paul is a nose picker.
3. (implied) What a nose picker claims is good is not good.
(implied) Therefore, universal healthcare is not good.
Ad Hominem is Latin for "against the man." One kind of this general fallacy is to discredit an opponent instead of his argument. For example:
1. J.P. Holding claims that the ancient Israelites were a group oriented people.This argumentation is in error because the character or attributes of a person almost always has no bearing on the validity of his claim. In this case, there is nothing about J.P. Holding's past job that affects Holding's claim, or the evidence he uses.
2. Holding quotes scholars to establish his point.
3. I say, "Holding wouldn't know, he used to be a librarian at a prison."
Therefore, Holding's claim is false.
However, sometimes an ad hominem reason is justified. For example, if
a politician is caught lying, that is a good reason not to vote for him. Or, if
a skeptic knowingly uses an out of date, sorely obsolete work as a primary
source, we should be suspicious of the rest of his work. If you see a certain Pope Leo X quote on a skeptic
website, run for the hills.
"But no fair," some may complain, "Holding is unruly when it comes to ad hominem attacks. Doesn't that mean he is wrong?" However, you will notice that Holding's style is "establish the validity of a point, then make the skeptic/cultist look silly" (or on occasion vice versa).
Nevertheless, it is often questioned whether a Christian ought to use any ad hominem at all. I'd say generally, in our day-to-day lives, it should be avoided. However, in the context of responding to hardened dissenters of Christianity, I agree with a Tektonics essay, and note how Jesus was less than meek in dealing verbal blows on the Pharisees in Matt. 23:13-38.
Also, sometimes you can turn a person's tactics or sources of evidence against his argument. He cannot very well protest; if he does, remind him or his hearers that he used the very tactic(s) that he is protesting. Lawyers call that estoppel. For example, science has resulted in useful theories, but it cannot be used to prove anything with certainty. However, if someone cites scientific evidence, that opens the door for you to use scientific evidence to persuade him that he is wrong (if ever that is possible). People have cited lack of evidence for the Hittite people to show that the Bible must be errant. However, now that we do have Hittite artificats, we can refute that line of argument. Hittite artificats or any other type of archeological evidence cannot ever establish Biblical inerrancy, but they are good for that kind of refutation.
The kind of Ad Hominem Argument above (Jesus v. Pharisees) is known as Abusive Ad Hominem, while another kind is known as Circumstantial Ad Hominem. Being more subtle, this subfallacy is raising an irrelevant personal point against the argument of the proponent. A common example is suggesting that an argument is bad because the proponent of that argument has a bias or agenda in favor of the conclusion of the argument. No argument is really refuted by pointing out the proponent's bias, except when sufficient evidence shows that the bias really affects the argument. The proponent of the argument could likewise, in response, dismiss the objection based on the bias of the objectee. Unless a character aspect of the proponent is relevant to a given argument, it shouldn't be brought up in a rebuttal.
Ambiguity is defined as, "1. Doubtfulness or uncertainty as regards interpretation; 2. Something of doubtful meaning." (The American Heritage Dictionary of the English Language. Fourth Edition. Houghton Mifflin Company. 2000. From Dictionary.com). An argument with ambiguous terms may be valid, but it may be invalid orirrelevant depending on how its terms are interpreted. A special case: the argument may simply be invalid because a term in it is taken in more than one sense.
Many different kinds of ambiguities exist:
1. Words that have multiple meanings: see Equivocation.
2. Words that sound the same but have a different meaning: i.e. "there, their, and they're."
3. Ambiguous grammar: "I saw a house fly today." Did you see a flying house, or the species of fly? In this case intuition tells us it is the latter. "All that glitters is not gold." This old saying could mean "Not all that glitters is gold" or "Nothing that glitters is gold." More than likely, the former was intended.
5. The target, connotation, or nuance of a phrase
6. A whole phrase, sentence, or even whole paragraphs that may have multiple interpretations if not interpreted in context: see Quoting Out of Context
7. Other (I am not aware of any others that are common in English, but I don't think this list is exhaustive).
This is a No. 2 kind of ambiguity:
Peter said he saw a housefly.The obviously wrong conclusion springs from misunderstanding the grammatical structure of the sentence. The last noun in the first sentence is really "housefly," a kind of insect, not "house."
Therefore, Peter thinks houses can fly.
The misunderstanding may be unintentional, and it is often hard not to misunderstand another person's point. "Boobytraps" -- statements that may cause another to make wrong conclusions -- abound in speech and writings. This is an especially bad problem in politics. For example, the phrase "government" have different meanings in different minds; other such common phrases are "the general welfare of the nation" and "national security."
You also have to watch out for intentional boobytraps: statements intentionally stated ambiguously so that a desired and wrong conclusion may be drawn from them. Politicians usually try to avoid specificities without appearing to do so. They are often accused of breaking promises, when in reality they may have only been guilty of being too general.
It is good practice to ask what is meant by this or that phrase. It may turn out that the speaker does not really know what he is talking about or his thinking is rather vague.
(Ambiguity can cause another kind of problem: Rather frequently people jaw against each other, though their positions are actually rather similar. The trouble is different semantics used by different people to represent what is really essentially the same position. In the early days of quantum theory, people debated the relative merits of Erwin Schroedinger's wave mechanics and Werner Heisenberg's matrix formalism for years, until some scientists showed that they were really equivalent, always predicting the same effects.)
Appeal to Authority (or, Appeal to False Authority, or Appeal to Questionable Authority, Argumentum Ad Verecundiam)
Let's face it. Not one person will ever become qualified as an expert in every field of research relevant to Apologetics. A person can spend decades studying only one field alone. Most laypeople will have to rely on experts from time to time to establish a point; even experts in one field of study will appeal to experts in another field. Appealing to an authority to make a point can be an acceptable way to make a point.
One must be cautious, however, as no authority is perfect. Authorities have been known to contradict each other, and being an authority doesn't make one infallible. So, it is recommended that one only uses an authority when, for whatever reason, it would be impractical or unnecessary to present the evidence or argument the authority represents. However, if one is responding to another's personal opinion, a professional opinion carries more weight in debate.
There are a few different ways to commit an Appeal to Authority fallacy: 1. When one uses a claim from an person not qualified to comment on the area one is making the argument in. For example:
Albert Einstein stated that, "God does not play dice."The conclusion may be correct (I'm not entirely sure), but the argument is fallacious because Einstein was an expert in science, not theology.
Therefore, random probability (luck) is in contradiction to God's sovereign plan.
2. Since authority is one of the weakest forms of evidence, one must not over-depend on the strength of an authority. The example above does, using the opinion of an authority as though it were absolute proof ).
3. Another kind of appealing to false authority is to state that something is
validated by "many" or "most" of a class of authorities. For instance, one can
say, "the majority of scholars think that the historical Jesus was just a really
good teacher." However, unless actual authorities are cited, this is a
fallacious appeal to unspecified authorities. Most philosophers agree with this
(take tongue and plant firmly in cheek).
Begging the Question (a.k.a. Circular Reasoning, Petitio Principii)
Circular reasoning occurs when the conclusion of an argument is contained in one of its premises. To the right is Sparky doing an interpretive dance of this fallacy. Another example:
1. The Gospels contain several prophecies of the Fall of Jerusalem and the destruction of the Temple.The argument should be rejected because premise 2 is in essence a generalization of the supposed conclusion. The person making the argument is said to "beg the question." Anything can be "proven" with circular arguments. That is, it is not really proven.
2. Any supposed prophecy of an event that actually occurred was probably written in hindsight.
3. The Romans attacked and destroyed Jerusalem (including the Temple) in 70 A.D. (i.e. Mat 23:37, 38; Mark 13:1-3).
Therefore, the Gospels were probably written after 70 A.D.
Cause and Effect Fallacy (a.k.a. Questionable Cause)
Did you know that cold weather causes illness? Or that the rise in Christianity in the last couple of decades caused the rise of immorality in society? Believe it or not, many people do believe the former (rather, bacteria and viruses cause illness), and I really have seen a skeptic assert the latter. The rise of immorality in American society has many complex causes, and it is likely that the rise of Christianity is incidental.
These two claims are cause-and-effect fallacies. If event B occurs just after event A or simultaneously, never jump to the conclusion that A causes B. Several possibilities exist:
1. One of the Protestant movement's most important doctrines is Sola Scriptura (Scripture alone).This argument is fallacious because no evidence is shown here that Sola Scriptura does indeed cause denominational fragmentation. I could likewise suppose that denominational fragmentation causes Sola Scriptura, or both have a common cause, or it is mere coincidence. Which is the case? Unless the person making this argument has the historical social science evidence to support that, it is invalid.
2. The Protestant denominations have since fragmented.
Therefore, Sola Scriptura causes denominational splitting.
Disjunctive Syllogism (a.k.a. Denying a Conjunct)
This fallacy is assuming that two (or more) propositions are mutually exclusive, that is, at most one of them is true; but that has yet to be demonstrated. For instance:
1. Either God is sovereign or man has free will.This topic of sovereignty versus free will is out of the scope of this essay, but I believe it is entirely possible that God, in his sovereignty, allowed some level of human choice. To allow free will, itself, is a sovereign decision. Thus, the conclusion would only follow from premise 2 if the two propositions in premise 1 were shown to be truly mutually exclusive.
2. God is sovereign.
Therefore, free will doesn't exist.
This example posits two truly mutually exclusive propositions:
1. It is either raining, or it is not.Now that argument is sound.
2. It is raining.
Therefore, "It is not raining" is currently untrue.
The Fallacy of Equivocation occurs when a word is used in two different contexts and is assumed to have the same meaning in both contexts, when distinct meanings ought to be preferred. Two examples:
1. All bushes are green and leafy.
Therefore, George W. Bush is green and leafy.
1. Isaiah 44:6 says, "Thus says the LORD, the King of Israel and his Redeemer, the LORD of hosts: 'I am the first and I am the last, And there is no God [elohym] besides Me."The former example should be obvious. But, the latter assumes that elohym conveys the same meaning in both passages. In reality, Isaiah 44:6 most likely refers to deity, whereas Psalm 82 either refers to angels or more likely the leadership of Israel. The Hebrew term elohym can refer to Yahweh, deity, or beings of power. Since many words in all languages have multiple meanings, anyone who wishes not to look like a fool should try to understand a word by understanding the context surrounding it. I mean come on, didn't we all learn this already in fifth grade? ;-)
2. Psalm 82 implies there are many gods [elohym]. (Ye are gods...)
Therefore, Isaiah and Psalms contradict one another.
Evolutionists often commit this fallacy: They discuss facts of evolution (=
genetic changes or diversity within a species), which creationists do not deny,
and conclude that they have proven evolution (= new species arising from old
species or life arising from simple goo ["goo to you by the way of the zoo"]).
A False Dilemma is similar to a Disjunctive Syllogism, in that only two alternatives are proposed. Typically, the two alternatives are extremes, so this is often called the Black-or-White fallacy. An example:
Either you accept Naturalism, or you are superstitious.In this case, it is assumed that the only alternative to the philosophy of Naturalism is superstition. The statement neglects the possibility of a well-thought-out and evidenced theism.
(Strictly speaking, a dilemma means just two alternatives. However, sometimes three or more alternatives are proposed yet leave out one or more alternatives.)
"I can't believe you are a Christian! Hitler was a Christian!" Though most skeptics shy away from this "reasoning" (and with good reason!), you still see it from time to time on the Internet. The above quote is an example of a fallacy known as Guilt By Association. In its most common form, this fallacy attempts to discredit an idea or belief by associating it with an undesirable person or a group. Thus, it is thought, no sensible person would accept the notion because they don't want to be associated with that person or group. It is clear that this kind reasoning is in error, as we can think of some very noble causes which have attracted some shady characters. One example might be that the women's rights movement has become associated with militant feminists in our society. Despite the fact that many people distrust feminists, this does not mean civil rights, in general, are bad.
A Genetic Fallacy occurs when the origin a belief or idea is presented as grounds to accept or reject the idea. Of course, this doesn't apply when the the origin itself is the issue, or that it is relevant to a truth claim (e.g., a strong argument can be made that the truth of Christianity is contingent on the truth of the Resurrection. If this is the case, then appealing to the supposed truth [or falsity] of the Resurrection does not commit the Genetic Fallacy). This is a common example of a genetic fallacy:
Most Christians are believers because their parents were.Typically, though not always, the suppressed conclusion is "therefore Christianity is not true." It is clear, even without counter-example, why this reasoning is fallacious. It is possible that Christianity be demonstrated true, even if all modern believers were Christians because they were born and raised in the Church.
The Hasty Generalization is a statistical no-no, when an observation of a rather small group is assumed to apply to a larger group. The most common kind of Hasty Generalization is stereotypes, overly broad generalizations of certain types of people. For example:
Some of the Christians I met are hypocritical.
Therefore, all Christians are hypocrites.
An atheist I met made some very irrational arguments.To be sure, induction -- generalizing from incomplete observations of a large group or some kind of phenomena -- is to some degree "hasty," because we can never be sure we know everything about the group. The art of sampling a large population so as to minimize the possibility of false conclusions at acceptable cost is rather professional and at times controversial and/or subtle. If we observe 100 birds that look like ravens and they are all black, it is reasonable to conclude that birds that look like ravens will be black. However, perhaps someday we will see albino ravens.
Therefore, most atheists are irrational.
This is not to say that we should always avoid generalizations. Actually, it
is practically impossible to do so; we cannot make decisions without making some
generalizations about the universe.
Appeal to Ignorance (a.k.a. Argumentum Ad Ignorantiam)
Have you ever noticed that no matter how hard you try to make a valid point, a certain opponent will simply bury his/her head in the sand? The appeal to ignorance is likely the tool of choice for such a person. An appeal to ignorance is when one cites lack of evidence against or for a proposition, with exceptions (to be discussed later). For example:
There is no evidence that God exists.
Therefore, God does not exist.
There is no evidence that God does not exist.Such reasoning is clearly fallacious, because the person making the argument could not possibly know all the necessary evidence.
Therefore, God exists.
However, sometimes one can rightfully appeal to lack of evidence. For
instance, bus schedules are assumed to be exhaustive, meaning if a given bus
schedule does not indicate that a certain bus will stop at a given place at a
certain time, then it is reasonable to conclude that no bus will stop at that
place at that time. Also, the US criminal court system operates on an "innocent
until proven guilty" system. If the prosecuting attorney fails to prove that the
defendant committed the crime, the jury is expected to assume the defendant is
Loaded Question (a.k.a. Complex Question)
"Why is George W. Bush so blood thirsty?" an antiwar activist might ask. Or, "Is oil worth the thousands of Iraqi lives we might kill?"
Do you want to make a claim, but don't want to prove it? If so, the Loaded Question just might be the tool for you.
A Loaded Question is a question phrased so that it forces an answer based on a false or controversial premise. In the above examples it is assumed that we are going to Iraq because Bush is bloodthirsty, or wants the oil in Iraq. The premises are probably based on opinion, not evidence.
We could likewise ask a man, "Have you stopped beating your wife, lately?" Whether he answers Yes or No, he admits to beating his wife.
If you don't give an answer to a loaded question but instead protest its
loading, sometimes you are accused of dodging it. Though many times a loaded
question is raised unintentionally, it is a common tactic to trap unwitting
debaters into agreeing with a questionable premise, or to accuse them of
"dodging an important issue." Thus, the apologist or skeptic (yes, we Christians
commit fallacies too) must pay attention to what is assumed in a question before
Appeal to Novelty (Appeal to the New)
An Appeal to Novelty is a fallacy that assumes the newness of a concept or object makes it better. An example:
Recently the Crumpaq company came out with the Dimensia 7000 series computers. A spokesman said, "The design architecture in the 7000 series is much newer than in the 5000 series." He continued, "This makes the 7000 far superior."Newness, in and of itself, does not guarantee quality.
Of course, often something new is better than something old. For instance, older cars get a lot of wear and tear, so new cars tend to be more reliable. Newer scholarship, based on recent findings in archeology, etc. may make older, conflicting scholarship obsolete. However, you will notice in these cases that the newness itself still doesn't guarantee truth. Someone might have made a big mistake building a car or writing a scientific paper. In particular, pay attention to advertising. Fallacies, like Appeal to Novelty, are commonly committed to sell products.
Poisoning the well is a form of Ad Hominem attack that occurs before the meat of an argument, biasing the audience against the opponent's side before he can present his case. For example:
Don't listen to him. He's an idiot.
You can make your case, but obviously any so-called historian who thinks the Gospels are true is deluded.Just like the typical ad hominem fallacy, poisoning the well is fallacious, since the character of a person or the people he cites generally has no bearing on the validity of his argument.
An appeal to popularity, as the name suggests, occurs when the popularity of a thought, argument, or object is appealed to as evidence that such is valid or superior to others. A couple of examples:
The majority of people in the world is opposed to the war in Iraq
Therefore, the war in Iraq is unjust.
"News 8, where more Michiganders get their news than from any other station."
Most scientists believe evolution is true [see also Appeal to Authority].
It should be apparent why appealing to popularity is fallacious. Simply put, to err is human. To avoid mistakes consistently well one must be exceptional. Also, humans are social creatures, so often someone accepts something just to "fit in." However, fitting in or majority rule is irrelevant to the validity of a logic claim. 1+1=2, no matter how many people are persuaded to believe otherwise.
Pay attention to the advertisements you see/hear. This fallacy is quite common in advertising. In politics, majority rule is often supposed to be wise, benevolent or whatever. However, Germany's Nazi past should be taken as a caution against such thinking. In science, according to people like Kuhn, paradigms (analogous to majority rule) give way to new paradigms, and we have no reason to think that the current paradigms will be the last ones ever.
Because most people reading this do so for apologetics, Quoting Out Of Context may be one of the most important fallacies for my readers. Far too often the Bible is quoted out of context (by both sides!), creating a supposed contradiction or a spurious doctrine. Context is so important that I tend to quote entire passages rather than individual verses.
Context usually is a key ingredient in the meaning of a quote. To be sure, not every instance of quoting out of context is seriously fallacious; sometimes it is better to be brief. However, do be careful not to change the meaning too much.
Once, I read about a woman who had a highly puritan-like standard -- so much so, that she didn't really enjoy much from life. When asked why she had such a standard, she quoted Colossians 2:21: "Do not handle, do not taste, do not touch!" However, when we read the passage this occurs in, we see:
If you have died with Christ to the elementary principles of the world, why, as if you were living in the world, do you submit yourself to decrees, such as, "Do not handle, do not taste, do not touch!" (which all refer to things destined to perish with use)--in accordance with the commandments and teachings of men? These are matters which have, to be sure, the appearance of wisdom in self-made religion and self-abasement and severe treatment of the body, but are of no value against fleshly indulgence. Colossians 2:20-23.
Here, Paul is not unpacking some deep truth, but instead is refuting a misconception. What we have here is a tidbit of false wisdom, "Do not handle, do not taste, do not touch," which looks good. But in reality, according to Paul, it is of no use to the believer who wishes to live a pure life. Thus, the woman was errantly quoting out of context in her use of Col. 2:21.
Though usually quoting out of context is unintentional, people do it intentionally, to protect some pet doctrine or attack some position.
A Red Herring is an irrelevant topic or premise brought into a discussion to divert attention from the topic at hand. Usually, the irrelevancy is subtle, so that it appears relevant to those not paying close attention. Of course, the Red Herring will not really win a debate, unless you are a stork, or a fisherman ;)
Patroitica: We must support the war in Iraq, because we have to finish what we started.
Economica: I would support the President with the War in Iraq, but I don't like his policy on the economy.
The slippery slope is a fallacy that asserts the result of some event without explaining how the result follows from the event. For instance:
If we allow creationism to be taught in public schools as an alternative to evolution, then next thing you know, they will teach a flat earth and a solid sky as an alternative to modern cosmology.
If they restrict pornography today, tomorrow they will take away all of your freedom of speech.If there was some reasoning that tells us how flat-earth-solid-sky teaching follows from teaching creationism or how loss of all freedom of speech follows from restricting porn, these examples would not commit the slippery slope fallacy.
A case of special pleading is a person's holding others to a different standard to himself (or someone who represents his case), without justification for the different standard. A Christ-myth skeptic asks a Christian to prove that Christ was real. When the Christian asks the myther to prove his version of Christ-myth is true, he refuses to. He must provide a reason why his belief is exempt from the same scrutiny the Christian's belief gets. If he doesn't give justification, or if the given reason is irrelevant, that is special pleading.
But of course, if a person who claims exemption from a standard does give a relevant reason for the exemption, it may be justified, depending on the strength of the reason.
A Sweeping Generalization is like the Hasty Generalization, except it runs in the opposite direction. Here, the error is applying a generalization to a case that is possibly exceptional. For instance:
1. Most men are "pigs."Why this is fallacious: Sweeping Generalizations neglect the fact that nearly every generalization has one exception or more. (If you think that fact is a hasty generalization, well, it's close to the truth anyway!) We have to remember not to interpret a generalization beyond what it actually tells us: only some or most of a class has a certain quality. Too often like the case above, a generalization is mistakenly applied to individuals as though it is universally true.
2. John is a man. [Though, John is a sensitive, incurably romantic.]
Therefore, John is a "pig."
As an aside, from time to time I see a generalization that is inacurate or just plain false get labeled as a "sweeping generalization." Loosely speaking, this is a correct use of language, but it must be noted that a bad generalization should not be confused with the Sweeping Generalization fallacy. (I would say that "most men are pigs" is blatantly incorrect, but I might be biased.)
The Strawman Fallacy is a type of Red Herring that attacks a misrepresentation of an opponent's position. The attack is often called "burning a strawman." It is a surprisingly common fallacy, because it is easy to misunderstand another person's position. Also, when one is losing a debate a strawman that is easy to attack is a most appealing target. Obviously, burning a strawman is fallacious, because even after the strawman is vanquished, the opponent's argument still has yet to actually be addressed.
Example (as if you weren't expecting any):
Calvinist: ". . . so God didn't choose us based on anything we do. Predestination is based on God's good pleasure."A subfallacy of Strawman is to take an extreme version of a person's position and attack it. According to Fallacy Files (see references below), this is called a Strawdemon.
Arminian: "So, He chose us arbitrarily. Do we serve a whimsical God?"
Mom: The doctor says that these exercises will help you recover more quickly.
Son: Aw, Mom! Do I have to look like Arnold Schwarzsengger?
Appeal to tradition, as the name suggests, is the fallacy of saying that a concept or thing is better because it is old, is traditional, or has always been done in the past. For example:
The tradition of the Catholic Church has been to baptize infants.Age or traditionalness of something does not make it better.
Therefore, infants should be baptized.
However, like Appeal to Novelty, sometimes older things do happen to be superior. For instance, wines and cheeses are generally better when aged. First- and second-hand testimonies are usually trusted more than third-hand accounts. Here, like Appeal to Novelty, some validating factor occurring with age or tradition is present.
There are two common ways to use analogies: using a familiar concept to help understand an abstract concept, or showing a subject has a property because an analogous subject has that property (I recall that C.S. Lewis did this a lot in Mere Christianity). In the latter category, we often see folks using a case or argument to show the strength or weakness of a similar argument.
For instance, recall the examples I used for the definition of a fallacy:
1. All dogs are mammals.
2. Toby is a mammal.
Therefore, Toby is a dog.
1. All cats are animals.The second argument might be thought of as an analogy of the first one. Hence, because the second conclusion is clearly wrong, it is reasonable to conclude the first argument is fallacious (even if all its statements are true).
2. J. P. Holding is an animal.
Therefore, J. P. Holding is a cat.
This is why I have an example of each fallacy: You can compare the example to a similar argument that might come your way or that you recall. However, one has to be cautious, as similarities can be deceiving.
Counter-examples can rebut many arguments-by-weak-analogy, like the second argument above can be used to rebut the first argument above. Here's an actual case from Tektonics. Frequently, to rebut Holding's article The Impossible Faith, another religion is supposed to have been as unlikely to succeed as Christianity has, but did anyway. That would be devastasing to "The Impossible Faith" case, if the alternative is sufficiently analogous to Christianity and its history.
...But that has shown to be a big "if." Take Mormonism, for example (see here). Upon comparison, we
see some relevant disimilarities:
Factor #1: Christianity's founder (Jesus) was subjected to great shame (the Cross). Joseph Smith also was, but to a lesser extent, in a society where honor and shame are not a critical issue.
Factor #2: Jesus had serious prejudices working against him. Joseph Smith may have had some prejudice against him, but by far not as bad as Jesus.
Factor #3: Physical Resurrection was offensive to Gentiles in 1st Century Rome. It was nearly accepted as fact in 19th Century America.
[To see the full list, click on the link above.]
In general, the weak analogy fallacy is when the case and its analogy have too many or large dissimilarities. There is no standard rule on how strong an analogy has to be to be useful, but weak analogies are usually recognizable.
Wishful thinking is a fallacy that posits a belief because it or its consequence is desired to be true. In this example, the person making the argument wants the Bible to be errant:
1. Inerrantists made a good explanation of the bat/bird issue.A belief is not valid simply because one wants it to be. I want the world to be made out of chocolate, and that my paid career be watching Simpsons reruns everyday. But alas, I am currently looking for an internship in networking; and the last I checked, dirt clods still taste like dirt (who knows, maybe that has changed since I was 8).
2. However, it seems more likely to me that the Bible writers were scientifically ignorant and didn't know bats weren't birds.
Therefore, the Bible errantly classifies bats as birds.
Wishful thinking is usually much less obvious than that. A particular kind of wishful thinking is called Appeal to Consequences.
Sel'fish: "If we don't do this [a course of action that will benefit Sel'fish making the argument but not his listener], the Goonies will eat us up."Here Sel'fish is hoping that his listener will commit the fallacy of wishful thinking.
Copi, Irving M. and Carl Cohen. Introduction To Logic (Eleventh Edition). Prentice Hall. Upper Saddle River, NJ. 2002.
Curtis, Gary N. The Fallacy Files. 2003. Nov. 4, 2003. <http://www.fallacyfiles.org/>
Labossiere, Michael C. "Fallacies." The Nikzor Project. Apr. 15, 2003. <www.nizkor.org/features/fallacies/index.html>
8/17/07: Revised Introduction
1/4/04: Miscellanious updates