A presumption fallacy occurs when an arguer shirks the burden of proof by presenting a premise that is just as much in need of proof as his conclusion. Remember that an argument is supposed to support a claim that we don't already believe by means of premises that we do already believe. If we don't already believe those premises, then those premises need to be supported by their own arguments. When an arguer relies on a premise that is clearly just as much in need of support as his conclusion, then he commits a presumption fallacy. Basically, in a presumption fallacy an arguer explicitly or implicitly assumes something that logically should not be assumed.

Another way of putting it is to say that you make some kind of presumption fallacy every time you mistake one of your own personal opinions for a fact.

The difference between relevance fallacies and presumption fallacies is that in the former the premises offered simply fail to support the conclusion while in the latter the premises offered do support the conclusion, but themselves have no more support than that conclusion has without them. (A helpful student suggested that a less boring way to say this would be "A relevant fallacy is attempts to prove a conclusion by offering thought that do not stand on its truth. While a presumption fallacy begins with a false assumption and fails to establish their conclusion.")

Recall that a premise is supposed to meet two different requirements. First, it is supposed to provide support for the conclusion. Second, It is supposed to be either uncontroversial or independently supported. That is, it is to be supposed to either be something that a properly educated, reasonable person would generally agree to without argument, or it is supposed to be backed up by a logically compelling argument of its own. Of course, reasonable people often disagree about what is uncontroversial, so some unsupported premises may be considered controversial by some people but not by others. That's fine in itself. The problem of presumption appears when an unsupported premise turns out to be pretty much exactly as controversial, and in the same way, as the conclusion it supports. People who already agree with the conclusion won't worry about this, but then, these people don't need an argument to convince them. People who don't already believe the conclusion won't believe the premise either, so this argument won't ever convince them. Either way, a question begging argument won't ever change any logical person's mind, so as far as logic is concerned, it isn't even an argument.

In this chapter, I'm going to say that a claim is "controversial" if it is something that at least some well-informed reasonable people would tend not to agree with and/or it is something that people would generally only agree with if they also already agreed with the conclusion of the relevant argument. If people who do not already agree with the conclusion of an argument would also strongly tend to disagree with one of that argument's premises, then that premise is controversial, as far as I'm concerned.

Begging the Question

An argument is begging the question when its main "premise" is either a restatement of its conclusion, or is otherwise so clearly unsupported that the listener instinctively wants to jump in and question that main premise. In other words, the argument relies upon a premise that's at least as controversial as the conclusion.
(It's called "begging the question" because it makes the listener want to jump in with "say what? How do you know that...")

The classic way to beg the question is to provide a "premise" that is nothing more than the conclusion expressed in different words.
We know that alien abduction stories are valid and accurate because the abductees are completely accurate in their reccollections of events. (And how do you know that these "abductees" are completely accurate?)

The question can be begged by presenting the conclusion as a specific instance of some general rule that itself is not backed up by any reasons.

My refusal to allow make-up exams is justified by the fact that it is not my policy to allow make-up exams.
(And what justifies the policy?)

Another way to beg the question is to think that because one has already made up one's mind, arguments can be judged good or bad based solely on whether or not their conclusions agree with one's pre-existing opinion.

I can't tell much about the logic of this argument, but it's conclusion is true so, yeah, I guess it's a logically compelling argument. (It's only a logically compelling argument if it's good enough to change somebody's mind. Even if the conclusion was true, how could that make the argument good? And how do you know that conclusion's true?)

The conclusion of this argument isn't true, so it's logic must be inadequate. (If you haven't looked at the logic, how could you know that it's inadequate? And how do you know that conclusion isn't true? If there's no problem with the logic of the argument, the conclusion is true, whether you like it or not.)

Rilda. That Punter Dublin is such a liar!
Joyce. Can you tell me one lie he's told?
Rilda. Well... no. But he's a liar, I know that!(How can you know that someone is a liar without knowing of any lies he's told?)
Joyce. What about Farmer Shrub? I can tell you a dozen lies he's told.
Rilda. Not in this house you won't! (How can you think that somebody's honest if you're unwilling to look at the evidence?)

Things that look like authority arguments can turn out to be mere question-begging. If someone says that some authority supports his conclusion, but doesn't tell us who that authority is, he then begs the question, and we can dismiss his argument.

Scientists have proved that we only use ten percent of our brains. (What scientists? When? How did they prove this?)

And here's a personal favorite.

Delilah. I don't think we should consider President Suharto of Indonesia a humanitarian leader. After all, he did lead Indonesia in an invasion and occupation of East Timor in which they killed about a third of the East Timorese.
Garrison. You're making that up!

This should be fairly easy, right? I mean, it should be clear that Garrison is begging the question. The trouble is, this set is based on a real conversation with a fellow graduate student. He really reacted like that. He heard something he didn't want to believe, so he immediately jumped to the conclusion that I had made it up. He even laughed. So let's make this perfectly clear: the automatic dismissal of information you don't like is always a fallacy. Always.

Here's another example.

We can see that everyone is really selfish simply by looking at society and noticing that everyone only acts to serve his or her own self interest.

This argument has a conclusion "everyone is really selfish," which is based on the premise that "everyone only acts as his or her own self-interest." So we could standardize this argument as follows:

Everyone in society only acts to serve his or her own self interest.
Everyone is really selfish.

But if we leave it at that, we might fail to notice a very interesting fact about this argument. Consider the definition of the term "selfish." The word "selfish" simply means "only acts to serve his or her own self interest," which means that the premise and the conclusion actually say exactly the same thing. This means that all of the following are in fact completely accurate standardizations of the above argument.

Everybody is really selfish.               People only act to serve themselves.
Everybody is really selfish.               People only act to serve themselves.

              Everyone in society is selfish.               Everybody only acts to serve his or her own self interest.
              Everyone in society is selfish.               Everybody only acts to serve his or her own self interest.

The advantage of standardizing the argument in one of these ways is that it really makes it clear how the premise is related to the conclusion. Of course, doing it this way also makes it clear that you need to be very careful to make sure that the premise of the argument you are standardizing really is the same as the argument's conclusion. If it turns out that there is actually a significant difference between the two, then you should not paraphrase them as saying the same thing.

Here's a more complicated example, which I discussed previously as a relevance fallacy: Steve Fuller, who (amazingly) works as a philosophy professor, appeared in the 2008 film Expelled: No Intelligence Allowed, in which he told interviewer Ben Stein that "Darwinism" leads to abortion and euthanasia. He said "If you take seriously that evolution has to do with the transition of life forms, and that life and death are just natural processes, then one gets to be liberal about abortion and euthanasia. All of those kinds of ideas seem to me follow very naturally from a Darwinian perspective-- a deprivileging of human beings, basically. And I think people who want to endorse Darwinism have to take this kind of viewpoint very seriously."

If we take this as an argument against Evolution Through Natural Selection, then it commits two presumption fallacies.

First, Fuller begs the question when he assumes that acceptance of evolution leads to being liberal about abortion and euthanasia. Saying that X leads to Y is a causal claim and it needs to be supported by a correlation argument, which Fuller does not provide.

Second, he begs the question when he assumes that what he calls a "deprivileging of human beings" is a bad thing. For something to be a bad thing it has to have demonstrably bad consequences, and Fuller has not even begun to demonstrate that "deprivileging" human beings has had any demonstrably bad consequences. It's just something he doesn't like.

Slippery Slope

The fallacy of slippery slope combines a whole string of presumed causal relationships. The difference between a slippery slope fallacy and a legitimate causal chain argument is that the legitimate argument depends upon a series of well-established causal relationships while the slippery slope includes at least one dubious or speculative causal claim.

Censoring hardcore pornography will soon lead to censorship of softcore pornography, which in turn will lead to suppression of harmless erotica like swimsuit photos, and that itself will finally cause censorship of nude pictures in medical textbooks.

If you make marijuana legal then it'll be magic mushrooms. If 'shrooms, then speed, and after that, peyote! Then cocaine won't be far behind. Which means crack! And what about heroin? And acid! Then there's angel dust, and finally those designer drugs that make people's heads explode! So if we make marijuana legal, decent people won't be able to sleep for the sound of all the exploding heads.

Would legalizing marijuana cause 'shrooms to become legal? Would legalizing 'shrooms cause speed to become legal? Would legalizing speed cause peyote to become legal? Would legalizing peyote cause crack to become legal? Would legalizing crack cause heroin to become legal? Would legalizing heroin cause angel dust to become legal? Would legalizing angel dust cause designer drugs to become legal? Is there anything about legalizing one drug that makes it impossible, or extremely difficult to avoid legalizing the next drug in the sequence? If there's any point where we can legalize one (relatively harmless) drug without having to legalize the next (more harmful) drug, the causal chain snaps, and the slippery-slope argument fails.

False Choice

An arguer commits a false choice fallacy when she leaves out a viable alternative. The usual way of doing this is to pretend that there are only two alternatives when there are fact more than two. (There's a name for doing it with exactly two alternatives but it won't be on the test.)

You should stop that protesting and support our president. It's America. Love it or leave it!

Russia has a choice. Stride forward in capitalism or turn back to communism.

Shamu is not a dog, therefore he's a cat.

Candidate principles:
1. You cannot love a country without unconditionally supporting its leaders.
2. Capitalism and communism are the only two possible political systems.
3. All animals are either cats or dogs.

This kind of fallacy can be committed with any number of alternatives, just so long as a reasonable alternative is left out.

Circular Argument

An argument is circular when questioning its dubious premise sooner or later leads right back to the unsupported restatement of the conclusion. (This can happen when someone attempts to save a question-begging argument by coming up another question begging argument for that question-begging premise. Keep doing that over and over, and you'll eventually start to repeat yourself.) An argument can only work if its premises are supported by existing, well-established knowledge, or by premises that themselves are supported by existing, well-established knowledge. An argument that attempts to support itself in mid air will always fall.
I know Jeff is honest because Marie insists that he is. And we can trust Marie because Rudy swears that Marie is absolutely honest. As for Rudy, well, Jeff insists that Rudy is absolutely reliable! (So the claim that Jeff is honest ultimately rests on... the claim that Jeff is honest!)

We know that astrology works because it has been validated by our best psychics. How do we know that validation by these psychics can be trusted? Simply because each of them has an astrological chart that indicates absolutely stunning psychic ability. (So astrology tells us that astrology is reliable.)

Benjamin. You should believe Rush Limbaugh is a political expert because Ben Stein says he is.
Shaylee. But is Ben Stein a good judge of political expertise?
Benjamin. Of course he's a good judge of political expertise! Rush Limbaugh says he's a genius!


The fallacy of accident, a presumption fallacy, occurs when an arguer applies a rule of thumb or general principle to a case that it clearly does not cover. He fails to recognize a valid exception to the rule. It's like equivocation because it stems from confusion (or dishonesty) about the meaning of a rule or saying, whereas equivocation stems from confusion (or dishonesty) about the meaning of a word.

Discrimination on the basis of race is wrong, so minority scholarship funds should be open to everyone.

Violence is wrong, so the cops shouldn't shoot back at that guy blazing away with an AK47.

Never draw to an inside straight, so I shouldn't draw even though my X-ray vision reveals that the cards I'd draw would fill my straight and win me that $42,000.000.00 pot.

Candidate principles:
1. You should never, never, never follow any policy that discriminates on the basis of race, no matter how morally necessary a particular such policy might be.
2. You should never use violence, even when you are being unjustly attacked in the performance of your morally necessary duties.
3. You should never draw to an inside straight, even when you know absolutely that doing so would make you an awful lot of money.

The reason for this fallacy is that people often forget that most of the rules we live by are rules of thumb rather than laws of nature. They were made up by smart people to cover situations that occur over and over again but they don't necessarily cover all possible situations. (Practice thinking up exceptions to various rules like "never play with matches," "never run with scissors" or "never eat anything bigger than your head.")

Here's another example:

Rocky: I just found out that the Reagan administration killed a unanimous Senate bill that would have punished Saddam Hussein's Iraq for it's use of chemical weapons against Iraqi Kurds starting with their March 1988 nerve gas attack on the civilian population of Halabja. The Senate wanted to cut Iraq off from loans, military and non-military assistance and U.S. imports of Iraqi oil, but the Reagan administration stalled the bill in the House until it died on the last day of that legislative session.
Eliezer: It's the president's job to ensure good relationships with America's trade partners. That assistance meant a lot to the Iraqis, and it would have soured relations with them if the United States had gone back on it's word. You wouldn't want the president to poison relations with other countries, would you? So obviously, stopping that Senate Bill from becoming law was the right thing to do.

Ensuring good trade relations is an important duty of the president, but it's not an absolute rule. He also has a duty to keep the US from doing morally wrong things, and from supporting tyrants and murderers abroad. Clearly, a duty to promote trade cannot override a duty to oppose tyrrany.

A version of this fallacy is committed by people who object to affirmative action on the basis that it is a form of discrimination. (There may be other reasons to criticize various programs of affirmative action, but I'll ignore them.) Segregation was outlawed because that it was a form of racial discrimination that caused great and long-lasting harm to all members of a segment of the American population. But it was the fact that it did unjustified, serious harm that justified banning it, not the mere fact that it was discrimination on the basis of race. Affirmative action, when properly applied, does justified and trivial harm to a few members of an otherwise generally privileged section of our society. We may criticize affirmative action for other reasons, but the mere fact that it is discrimination on the basis of race is not enough reason to ban it.


The fallacy of weaseling, another language fallacy, is sort-of another form of equivocation. Where the usual form of equivocation keeps a word but substitutes in a different meaning for that word, weaseling pretends that something should be called by a different word than the one that is really appropriate. This is done where the right word would reveal something that the speaker does not want revealed. (I suppose that it's possible for someone to weasel unintentionally, but generally speaking people who weasel should properly be referred to as lying bags of scum.)

One of my friends recently came up with an absolutely classic example of weaseling. We were talking about whether or not using the power of the state to create peer pressure on children to reverently utter the words "one nation under God" constituted a state effort to establish religion, and he came up with "Well, you know, the meaning of the word 'God' has changed in our society." This was an effort to imply that the words "one nation under God" in the pledge of allegiance didn't mean "one nation under God" when they were said out loud, or that reverently saying a phrase that clearly implied that his god existed and had authority over Americans was somehow not an affirmation of his god's existance and authority.

In this example, Larissa is not weaseling

7. Uriel. You know there's a moral rule against killing human beings, right?
Larissa. Of course I do! It's a very, very serious thing to violate the rule against killing people.
Uriel. So you must agree that the death penalty is morally wrong, since it involves killing people.
Larissa. Oh, no, I forgot about murderers. I think the rule here is that you shouldn't kill innocent people. Killing murderers might be wrong, but it doesn't violate the rule against killing innocent people, and that's a clearly justified moral rule. A rule against killing anyone at all isn't so clearly justified.
Uriel. Now you're just weaseling. First it's "thou shall not kill people," now it's "thou shall not kill innocent people." Moral rules are universal, you know, and you can't just go changing them about to suit yourself.

There's actually two ways to think about weaseling. The first is to treat it as a form of magical thinking regarding language, with the candidate principle of "if something can be given a positive-sounding or inoffensive name or description, then it has to be a positive thing." The second way is to treat it as another form of suppressed evidence, with the candidate principle of "facts I can ignore don't count." Either way, it's at least irrational, and may even be dishonest. Don't do it, and don't be fooled by it.

Okay, there are other language fallacies, but they occur so rarely I'm not going to mention their names. The only thing you really need to know about them right now is that there are other ways to go wrong with language. People can mess with the definitions of words, either by writing their own definition of the word in an attempt to distort the way someone else uses the word, or by citing a dictionary definition in a case where some other definition was clearly intended by the speaker. You can call these "equivocation" or "weaseling" depending on whether you think the speaker is confusing two legitimate usages of a word (equivication), or trying to distort the single, basic, meaning of a word (weaseling).

Self Contradiction

The fallacy of self-contradiction happens in extended arguments or conversations when the arguer uses a particular rule at one point, and then appeals to the opposite rule at another point in the same extended argument for a single thesis. Thus he simultaneously claims that a particular argument or standard of proof is both good and bad. It's good when he uses it, bad when you use it.

Elron. You should worship the true god Fnorbert, and not the false god Eki-Eki-Eki-Fatang-Fatang because the followers of Eki-Eki-Eki-Fatang-Fatang base their belief on nothing but their faith that Eki-Eki-Eki-Fatang-Fatang exists, and as we all know, faith is just another word for belief, and belief by itself proves nothing.
Princess. Well, that seems to refute Eki-Eki-Eki-Fatang-Fatang, but why should I believe in Fnorbert?
Elron. If you just have faith, then you will know for certain that Fnorbert exists.

Zoomer. We can discount professor Toohey's hypothesis because it's only 92% probable according to our available data. With professor Toohey's hypothesis out of the way, we are left with my hypothesis. My hypothesis is supported to 89% probability by the available data, which means we should accept it, since it's the only hypothesis we have left.

Stinky. The great god Vuntag determines what morality is.
Potch. How ya figure?
Stinky. Well, Vuntag can condemn us to everlasting torment, so obviously what ever she says to do is the morally right thing to do.
Potch. Well, Saddam Hussein can condemn people to years of torment, does that mean that what he says to do is the morally right thing to do?
Stinky. Of course not!
Potch. But if Saddam Hussein could condemn people to everlasting torment, that would mean that what he says to do is the morally right thing to do, wouldn't it?
Stinky. Don't be stupid. Being able to inflict everlasting torment wouldn't make Saddam Hussein determine what morality is.

If faith works for Fnorbert, it works for Eki-Eki-Eki-Fatang-Fatang. If 92% is low enough to reject professor Toohey's hypothesis, 89% is low enough to reject Zoomer's hypothesis. If the ability to inflict everlasting torment wouldn't make Saddam Hussein determine what morality is, then it wouldn't make Vuntag determine what morality is.

Basically, in a presumption fallacy an arguer explicitly or implicitly assumes something logically should not be assumed. In begging the question, the arguer more-or-less assumes the very thing he is supposedly trying to prove, so something that is so close to it that it might as well be the same thing. In other types of presumption fallacy, the arguer illegitimately assumes things that would, if true, imply that his conclusion is true.

Here are some exercises to work on..

29. Jasmyn. You keep telling me that the testimony of believers in Vuntag can be absolutely relied upon as proof of Vuntag's existence. But by that logic, the testimony of believers in Phobodisda can be absolutely relied upon as proof of Phobodisda's existence. So if Vuntag exists, so too does Phobodisda. Since they can't both exist, the rule that testimony of believers constitutes absolute proof can't work for anyone, not even Vuntag.
Efren. The trouble with that reasoning is that you are suppressing a vital piece of evidence. Vuntagian testimony can be relied upon as proof of Vuntag's existence, because it is backed by divine revelation from Vuntag, but Phobodisdan testimony cannot be relied upon as proof of the existence of Phobodisda because it is not backed by divine revelation from Vuntag.

Explain Self Contradiction.
s. If a rule is valid,, does that mean it's valid in every situation to which it can be applied?
t. Are there any logical rules that work for one person but not for someone else?

1. (Paraphrased from an actual column by Ann Coulter) It's ridiculous to say that the US government is engaged in a relentless, single-minded march towards war with Iraq, since it will be two whole years after 9/11 before we attack.

Robert: I really don't see why I should believe in Vuntag, after all, there really isn't any concrete evidence of her existence.
Mary: But you are ignoring the fact that Vuntag condemns all unbelievers to an eternity of being forced to watch Dukes of Hazzard reruns! So you'd better believe in Vuntag or you will find yourself spending all of eternity having to watch Bo and Luke foil Sheriff Lobo.

3. Elizabeth. I want to thank you for this book you gave me on voodoo. And I appreciate your attempt to help me deal with my many enemies, but I really don't see how sticking pins into little wax figurines is going to kill anyone.
David. I understand that you need some reason to believe that voodoo works. I can give you that reason. You can be sure that voodoo works, because it really is an effective way of hurting your enemies.

James. We have good reason to think that the universe is deterministic. After all, all our technology, and in fact all of our attempts to accomplish anything at all always assume that each particular cause will inevitably bring about the same effect it has always done. We couldn't make any plans if we didn't assume that the universe is deterministic. Since we successfully make and carry out all kinds of plans, it follows that the universe is deterministic.
William. You're forgetting one thing. Free will. We know that determinism isn't true because we also know that we have free will.

5. Ruskin. It seems to me that of all the Christian sects, Mormonism is the most misunderstood. I think it is somewhat unfair for the World Council of Churches to exclude the Mormon Church as non-Christian, since all the Mormons I've ever heard of treat the figure of Jesus with exactly the same significance as all the churches that the WCC does consider "Christian."
Dusty. I'm tired of hearing Mormonism described as a Christian religion. It seems that people like you are willfully ignorant about the facts of Christianity. It is easy to see that Mormonism is not a Christian religion. All you have to do is pay attention to the fact that the "Jesus" of Mormonism is not the Jesus of Christianity. Mormonism could only be a Christian religion if their Jesus was the same as Christianity's Jesus. Since he is not, they are not Christians.

6. Reanna. The first thing you have to realize is that The Book of Vuntag is absolutely right about everything, particularly in it's claims about morality. In fact, the Book of Vuntag actually defines what morality is.
Johan. But The Book of Vuntag tells me that it is immoral for someone to be left-handed. It also tells me that everybody should persecute left-handed people until they change their ways, and torture or kill them if they don't. Left-handed people don't hurt anyone else, and they can't help being left-handed, so the Book of Vuntag has to be wrong about that.
Reanna. Much as we might regret the unfortunate necessity of persecuting left-handed people, we know that the Book of Vuntag is right about morality because Vuntag says so! And Vuntag cannot lie.
Johan. But what makes you think that Vuntag even exists? And how can you be certain that Vuntag cannot lie?
Reanna. Oh Johan, Johan, my poor foolish Johan. Don't you know that it's all written in the Book of Vuntag

Isaias. You know, you'd better start believing in Fnorbert.
Joaquin. Not that again! You still haven't given me any credible reason to believe in Fnorbert.
Isaias. Here's your reason. Fnorbert punishes unbelievers very harshly, so you'd better get on the right side now.
Joaquin. So if he exists, and I don't believe, eventually he'll hurt me very badly?
Isaias. Exactly. You've got it now!
Joaquin. But you still haven't given me any reason to believe he exists, so I don't think he does.
Isaias. What are you, stupid? I just gave you a heck of a good reason!
Joaquin. Nope, you didn't give me any reason at all.

Jane. The state should legalize gay marriage, because people in committed homosexual relationships deserve exactly the same legal protections as people in committed heterosexual relationships.
Welsh. You're forgetting the fact that there are only two kinds of relationships, the committed, deeply loving relationships we have between heterosexual couples, and the impoverished, purely sexual relationships that exist between homosexual couples.

Vaughn. I think you are finally going to be convinced about the reality of the god Vuntag. Professor Slobbert's book Footsteps of Divine Vuntag finally has the proof you're looking for.
Anjali. I read that book ten years ago! It's best argument was the claim that Mat Tel, a priest of Vuntag, raised Clay Moore from the dead in the town of Punji Stick. I would have been impressed, but it wasn't documented with any evidence from Punji Stick, and so I had to discount it.
Vaughn. Well, the second edition of Footsteps has the documentation you're looking for. It turns out that the people of Punji Stick put up a monument to the day that Mat Tel raised Clay More. Here's a picture of the monument.
Anjali. Wow, it's a big one! And it even has a picture of Mat Tel raising Clay More. Wait, this picture looks exactly like the sketch of Mat Tel raising Clay More that Prof. Slobbert drew in his book! That's a bit of a weird coincidence, isn't it?
Vaughn. Oh I can explain that. The town council decided to build the monument after they all read Professor Slobbert's book five years ago, so naturally they used the sketch from the book since no-one in the town happened to know anything about the story before they read the book.

Diana: I sympathize with you about Abmiel, but he's entitled to follow his own religious beliefs.
Theresa: Abmiel won't marry me just because I'm a consecrated priestess of the fiery leaping goat-goddess Bloodfang and he is committed to building a christian family as part of creating the Kingdom of God on earth. That's religious discrimination, so he should marry me!

11. Omari. I still don't see why you think that unregulated gun ownership is necessary for the existance of a free society. Great Britain is a very free society, and gun ownership is strictly regulated there.
Daisha. Look, the basic question you have to ask yourself is, Do I want to live under a tryannical government that makes it extremely difficult for law-abiding citizens to own guns, or do I want to live in a free society where gun ownership is recognized as a basic right of law-abiding citizens?

Do the following questions closed book, and then test yourself by looking up the answers in this chapter. Repeat until you can answer every question correctly off the top of your head.

12. In logic, is an arguer allowed to assume controversial claims as premises?

13. Can an argument that relies on ruling out alternatives to the conclusion succeed if it fails to rule out all of the alternatives to that conclusion?

14. Can a group of "authorities" succeed in certifying each other as real authorities if the only reason for thinking that any one of them is a real authority is the fact that one of the others says that he is?

15. What is a rule-of-thumb? Is a rule of thumb the same as a genuine logical (or moral) principle?

16. Is a rule-of-thumb valid in a case where the underlying justification for having the rule clearly doesn't apply?

17. Can I rationally say that some rule is a true logical principle if it's obvious that this rule would be absolutely invalid if applied outside of my argument?


1. Coulter's argument can be summarized as:

It will be two whole years after 9/11 before the United States attacks Iraq.
he US government is not engaged in a relentless, single-minded march towards war with Iraq.    

This argument commits two red herrings . First, there is the introduction of the two-year time period. How could the fact that something takes two years mean that it is not a relentless, single-minded march towards war? When one country deliberately plans to attack another, it generally takes a couple of years to get ready, so the fact that the Iraq war was two years in the making does not by itself mean that the people planning the war have seriously considered any other options. The other red herring is the mention of 9/11. Since Iraq had nothing to do with 9/11, that date has nothing to do with whether or not the American government is relentlessly marching towards war.

Coulter's argument is analogous to:

In 1938, it had been 20 years since Britain and France defeated Germany.
Germany is not engaged in a relentless, single-minded march towards war with Russia.

Any student of history will tell you that this is ridiculous. Since it uses exactly the same candidate principle as Coulter's argument, it follows that Coulter's argument is ridiculous.

2. Robert's argument can be standardized as:

There is no concrete evidence of the existence of Vuntag.
(We should not believe in things for which there is no concrete evidence.)
We should not believe in Vuntag.

Mary's argument can be standardized as:

(Vuntag exists).
Vuntag punishes all unbelievers by forcing them to watch Dukes of Hazzard reruns eternally.
(There is no way for unbelievers to avoid the psychotically small-minded revenge of Vuntag.)
We should believe in Vuntag.

Based on this, Vuntag does not exist, and we should not believe in her. As with any supernatural being, our initial presumption must be that Vuntag does not exist since all the evidence we have strongly supports the position that no supernatural beings exist. Therefore Mary bears an extremely heavy burden of proof. She tries to meet this burden of proof by threatening Robert with dire consequences if he does not believe. (Fallacy of force.) These consequences are only a possibility if Vuntag actually does exist, so she has to prove the Vuntag exists before she can prove that there is any danger to Robert. (Here she commits the fallacy of begging the question.) Since she doesn't provide any evidence for Vuntag's existence, she loses the argument.

3. Elizabeth's argument can be standardized as:

There is no obvious mechanism by which sticking pins into wax figurines can kill anyone.
Voodoo doesn't work.

David's argument can be standardized as:

Voodoo is an effective way of hurting your enemies.
Voodoo does work.

Well, if it's true that voodoo is an effective way of hurting your enemies,then it absolutely follows that voodoo does work. But that's mainly because the sentences "voodoo does work" and "voodoo is an effective way of hurting your enemies" mean basically the same thing. David's argument begs the question. Given that the burden of proof lies on David to prove that such a contrascientific practice as voodoo can have any effect at all, this means that the only reasonable conclusion here is that voodoo does not work.

4. James's argument can be standardized as:

Our technology would only work if determinism is true.
Our attempts to accomplish our goals would only work if determinism is true.
(Our technology works.)
Determinism is true.

William's argument can be standardized as:

Free will exists.
(If free will exists, determinism isn't true.)
Determinism isn't true.

William's argument is analogous to

We know that Christianity is not true because cheese exists.


Cheese exists.
Christianity is false.

It's possible that William believes that free will and determinism are mutually exclusive. But this is not something he can just assume. It is something that he has to prove. Since he doesn't bother to give a reason why anyone should think these two things are mutually exclusive, he is begging the question. Based on the arguments given above, determinism is true. Although it is a fact that science and technology would not work if determinism wasn't true, it's sometimes hard to see why this is true, and most people could be forgiven for thinking that our initial presumption would be that we don't know whether or not determinism is true. James's argument gives us the basic reasons to think that determinism is true, and I don't see anything wrong with his logic. William offers a claim of fact that he believes contradicts James's conclusion. However, there are two problems with his logic. First, because he doesn't give us any reason to think that free will exists, the most he could prove by holding that free will and determinism are mutually contradictory would be that free will does not exist. Second, however, he only presumes that freewill contradicts determinism. He doesn't prove that either. Since our initial presumption about free will is that it exists, (since we perceive ourselves acting freely), it follows that William is begging the question on the issue of whether or not free will contradicts determinism.

5. Dusty begs the question of "what makes you think that the Church of Jesus Christ and the Latter Day Saints is talking about a different Jesus?"

6.  I'll do Johan's argument first.

The Book of Vuntag makes at least one false claim about morality.
The Book of Vuntag is not absolutely right in all it's claims about morality.

Here's Reanna's arguments.

Vuntag says that the Book of Vuntag is absolutely right in all it's claims about morality.
Vuntag cannot lie.
The Book of Vuntag is absolutely right in all it's claims about morality.

This is supported by.

The Book of Vuntag says that Vuntag cannot lie.
The Book of Vuntag is absolutely right about everything
Vuntag cannot lie.

This is basically a circular argument. The Book of Vuntag is cited as an authority about morality. This claim of authority is backed up by citing Vuntag himself as another authority. But then the claim that Vuntag exists and is an infallible authority is backed up by citing the Book of Vuntag, which puts us right back where we started. Based on the information presented above, the book of Vuntag is not completely accurate about morality. Johan proves this by giving one instance of a false moral claim found in the book of Vuntag. Reanna tries to defeat this argument by claiming that the moral claim Johan cites is in fact true. She justifies this by claiming Vuntag as an authority for the veracity of the book of Vuntag. Then he tries to support the authority of Vuntag by claiming the book of Vuntag as an authority. This is the fallacy of circular argument, so it obviously does not defeat Johan's argument.

7. Isaias uses scare tactics when he threatens Joaquin. He also commits begging the question when he assumes that Fnorbert's assumed psychotic cruelty is a reason to believ that Fnorbert exists.

8. Welsh commits false choice.

9. Vaughn commits circular argument.

10. Theresa commits accident

11. Daisha commits false choice.

12. In logic, an arguer is not allowed to assume controversial claims as premises.

13. An argument that relies on ruling out alternatives to the conclusion cannot succeed if it fails to rule out all of the alternatives to that conclusion.

14. A group of "authorities" cannot succeed in certifying each other as real authorities if the only reason for thinking that any one of them is a real authority is the fact that one of the others says that he is.

15. A rule of thumb is a simple rule that stands in for a more complicated rule in most circumstances. A rule of thumb is not the same as a genuine logical (or moral) principle.

16. A rule of thumb is not alid in a case where the underlying justification for having the rule clearly doesn't apply.

17. If it's obvious that a rule would be absolutely invalid if applied outside of a particular argument, then it's clearly not a real logical principle, and it doesn't count anywhere.