Logical Fallacies

Written: 1999.07.27
Last revised: 2002-02-19

Ad Hominem Attack
Appeal to Authority
Begging the Question / Circular Logic
False Cause
False Dilemma
Burden of Proof
Golden Mean
Style over Substance
Red Herring
Slippery Slope
Hasty Generalization
Leap in Logic
Stolen Concept

The Ad Hominem Attack

The Ad Hominem attack focuses on the man, not the argument. For example:

"Mike Wong has a very insulting manner. His attitude toward creationists is a perfect example of this mentality; he's always calling them ignorant, or stupid, or irrational, etc. You can't take someone's opinions too seriously when he exhibits that kind of behaviour."

"I found a nitpick error somewhere in Mike Wong's huge site, thus destroying his credibility. His arguments can be discounted, as he is clearly incompetent."

"Mike Wong is biased towards Star Wars. Everything he says is based on that bias, so you really shouldn't listen to what he says."

"Mike Wong is just a mechanical engineer, not a world renowned scientist. His arguments do not carry the weight of authority behind them."

The problem with this reasoning can be identified most easily by applying it to famous historical figures.

"Isaac Newton was a prick. If you ever read about the way he behaved, you'll see that. Therefore, force does not equal mass times acceleration."

"Albert Einstein was wrong about quantum mechanics, thus destroying his credibility. Therefore, E does not equal mc squared, since he was clearly incompetent."

"Nikolai Tesla was biased against Thomas Edison because of their public feud. Everything he said was based on that bias, including his push for AC power. Therefore, AC power is not better than DC power."

"At the time he wrote his theories of relativity, Albert Einstein is just a lowly patent clerk, not a world renowned scientist. Therefore, those theories should be ignored."

I'm not going to debate about whether I'm the world's greatest guy, or whether I'm justified when I start insulting certain people (I feel that I am, but that's neither here nor there). I'm certainly not going to pretend that I'm incapable of making mistakes, or that I'm the only person in this whole debate who has no bias whatsoever. But an argument stands or falls based on the accuracy of its data and its logical consistency, not the character of its author.

The Appeal to Authority

The Appeal to Authority is the idea that you can prove something by simply quoting a "higher up". For example:

"Mike Wong uses a lot of mumbo jumbo to show that transporters can't perform matter to energy conversion, but Lawrence Krauss says they do. Since Lawrence Krauss is a world-famous physicist and Mike Wong is just a lowly engineer, I trust Krauss more than Wong. Besides, I've talked to my physics professor and he says Mike Wong is full of shit."

This particular example illustrated all of the problems with the appeal to authority in one fell swoop. Let's see a real-life analogue:

"Where do you get off saying there's no scientific evidence for the existence of God? Stephen Hawking is a world-famous physicist and one of the world's top scientist, and he believes in God. So did Albert Einstein! If they think there's scientific evidence for God, then why don't you? Besides, I found a book written by a scientist, listing all kinds of scientific evidence for the existence of God."

In both cases, by simply using names and/or qualifications as "proof" without any other supporting logic or evidence, the argument relies upon several key assumptions:

  1. The "authority" is not just knowledgeable or smart; he is actually perfect, ie- infallible. Therefore, if he says something, it must be true.

  2. The "authority" is actually saying what this person thinks he is saying.

  3. The "authority" is real, is not lying, etc.

These assumptions are logically indefensible, as we look at them individually:

  1. Nobody is perfect and omniscient, therefore nothing can be "proven" by simply showing that any given person thinks it's true. You still need logic and evidence. All of these world-renowned experts used logic and evidence to support their own ideas. None of them could have simply said "I'm a genius, so I'm right". So why should anyone else be able to appeal to their authority, if they won't do it themselves?

  2. People's opinions are taken out of context all the time, and it's all too easy to make it appear that someone thinks the opposite of what he actually thinks. For example, Lawrence Krauss says that transporters won't work, and he cites the inherent unworkability of the "matter/energy conversion" idea as proof. In other words, in his own way, he is actually saying the same thing I'm saying: they can't possibly perform matter/energy conversion. Similarly, neither Stephen Hawking or Albert Einstein are Christians, but their words have been obscenely twisted to make it appear as if they are.

  3. When people don't even bother to name an authority, one must wonder whether that authority even exists at all. Did someone really have this conversation with his anonymous physics prof? How are we to know? Does this unnamed book of scientific evidence for God exist? How are we to know? And even if the "authority" is a real person, what if he's simply lying? What if he's lying about his credentials (very common among creationist "scientists") or worse yet, lying about his data?

Given its many flaws, it's amazing how popular the appeal to authority is. However, I have noticed that some people go too far the other way, and attack any attempt to reference someone else's work as an appeal to authority. This is almost as bad; people often reference the work of others (eg- "as Stephen Hawking showed, it is theoretically possible for energy to escape a black hole"), and this time-saving practice is distinguished from the fallacious appeal to authority for several reasons:

  1. The statement as written is true: Stephen Hawking did show that it is theoretically possible for energy to escape a black hole. Stephen Hawking's opinion is not being misrepresented as proof. If someone said "Stephen Hawking said so, therefore it is proven that energy really does escape black holes", then it would be an appeal to authority, but there is nothing wrong with simply referencing someone else's activities.

  2. It is the author's own paraphrase of Stephen Hawking's conclusion. If challenged, the author must be able to explain the concept himself, not simply refer people to semantic interpretations of a quote taken out of context.

  3. Stephen Hawking's background is relevant to the subject (which distinguishes it from the appeal to irrelevant authority, ie- a world-renowned mathematician speaking on matters of molecular evolution). This still doesn't constitute proof, but it does mean that his theories incorporate far more knowledge and study than something that a layperson might generate. Therefore, while it might be wrong, you would need a correspondingly rigorous alternative theory to dethrone it. Something that your cousin Eddie thought up while sitting on the toilet would not qualify.

Begging the Question/Circular Logic

This is the trick of stating the conclusion as a premise. For example:

"Mike Wong says that Borg drones can't adapt to SW blasters or modern firearms. However, it is a known fact that Borg drones have the ability to adapt to any weapon. Therefore, sooner or later, they will adapt."

A popular real-life example:

"Blacks and whites were never meant to live together. They're fundamentally different on too many levels. Therefore, any attempt to promote racial harmony would only upset the laws of nature, and cause more trouble. The only solution is racial segregation."

In both cases, the logic is circular because the premise includes the conclusion, and vice versa. In the first case, he starts from the premise that Borg drones can adapt to any weapon, in order to prove that they can adapt to any weapon. In the second case, he starts from the premise that blacks and whites are too different to live together, in order to prove that blacks and whites are too different to live together.

False Cause

This is actually a whole family of fallacies, in which A is incorrectly assumed to cause B. For example:

"We saw the Executor lose its bridge shields after a hit to the globes on top of the bridge tower. Therefore, you can take out any Star Destroyer's shields by shooting the globes."

"An asteroid took out an ISD bridge tower in TESB. Therefore, the KE of that asteroid must be the upper limit of Star Destroyer shielding."

And some real-life analogues:

"Within ten years after the widespread appearance of TV in any country, the murder rate doubles. This proves that television causes violence, not firearms proliferation or socio-economic disparities."

"The USS Arizona was destroyed by an 800 kg bomb. Therefore, you need less than 4 GJ of chemical energy to destroy a WW2-era US battleship."

In order, these are "post hoc" (if event A precedes event B, event A must have caused event B), "complex cause" (if event A can be shown to have contributed to event B, assume that it is the only cause of event B), "joint effect" (if A and B both change, assume that A caused B even if both might have been caused by a third factor), and "complex cause" again.

In the first case from Star Wars, the globes are shielded themselves (as we can see earlier in the same battle, when an object explodes against a clearly visible forcefield before crashing into one of the globes). Therefore, the shields must be taken down before you can destroy them. This means that event B actually preceded event A, so event A obviously did not cause event B. In the second case, an asteroid took out an ISD bridge tower but that ISD had been continuously taking damage for an extended period of time in the asteroid field, and it had engaged Rebel defenses in the Battle of Hoth before that, so it's preposterous to assume that nothing but that asteroid could have contributed to its bridge shield failure.

In the first case from real life, the introduction of TV is actually a symptom of wide-ranging social changes. Widespread TV proliferation never happens in a given country until after electrical infrastructure has been added, not to mention a populous middle class which can afford them. It does not take a genius to see that it cannot be regarded as a completely independent variable. In the second case, he assumes that it was the chemical energy of the bomb which destroyed the Arizona, even though it would not have done so if it had not hit the Arizona in precisely the right spot.

As an aside, real-life scientists use controlled experimentation precisely because they are aware of the complex cause fallacy. They know that you cannot assume a causal connection between factor A and event B when multiple independent factors are changing, so it is necessary to tightly control every factor except for factor A. If those other factors are not controlled, then the experiment is considered a waste of time.

False Dilemma

This is the trick of artificially limiting choices in order to create the appearance of an intractable dilemma. For example:

"If phasers work on a chain reaction, then why doesn't it spread through an entire planet?"

"In The Wounded, we heard dialogue stating that the Phoenix destroyed a Cardassian warship at a range of 300,000 km. However, in episodes such as A Call to Arms or Redemption, combat appears to happen at ranges of 5 km or less. This is a serious inconsistency in Star Trek, so we have to decide what to go with: the visuals or the dialogue. I choose dialogue."

And in real life:

"Half an eyeball is useless, so there's no reason to have an eyeball unless it's complete. But evolution theory says that all biological change is gradual, so it can't explain how the eyeball suddenly appeared!"

"If we allow frivolous lawsuits, then we encourage a lottery mentality, and unscrupulous people use lawsuits to get rich. But if we outlaw them, then we eliminate the only way individuals can seek legal redress against negligent corporations. Of the two, the former is the lesser evil. Therefore, we must continue to allow frivolous lawsuits.

In all cases, the person makes no serious effort to resolve the dilemma because he wants it to appear unsolvable.

In the first Star Wars example, the person makes you choose between "unstoppable chain reaction" and "not a chain reaction at all", even though the there are countless boundary conditions which might limit a chain reaction (and do, in real life). In the second example, the person makes you choose between visuals and dialogue, even though there is no conflict in the examples he gives. The Phoenix fired torpedoes at very long range against a lone Cardassian ship in "The Wounded", while much shorter ranges were used in the fleet melees of "A Call to Arms" and "Redemption". However, if heavy ECM is present in fleet engagements, long-range targeting accuracy may drop precipitously, and it would make sense that they don't waste missiles by firing them at long range, so the two incidents can be reconciled. Moreover, he artificially crystallizes Star Trek combat into two camps: "dialogue = long range" and "visual = short range", even though there are numerous pieces of dialogue which indicate short range (Picard says cloaked vessels usually attack from just three km range in "Hero Worship", and Worf uses manual targeting to kill a BOP in "Redemption"), and numerous visuals which suggest long range (TOS combat, in which enemy ships are never seen in-frame with the Enterprise). He is deliberately oversimplifying in order to force you to choose either A or B, even though it is possible to take both A and B in this case.

In the first real-life example, the creationist assumes that given a gradual evolutionary process, there must have been a sudden leap to an incomplete eyeball (which doesn't work) or no eyeball at all. He ignores the third choice: primitive light-sensitive organ. A single light sensitive cell could evolve into a pile of light sensitive cells, which eventually form a surface depression. The depression might become larger over time until it was a pit, and then at some point, fluids might fill that pit, thus protecting the cells at the base. It could have evolved a surface membrane at that point, which would eventually become the outer surface of the eyeball, someday evolving into a lens. Voila! Eyeball, with no stupid leap from nothing to "half-formed eyeball". In the second real-life example, the lawyer asks us to choose between "unrestricted frivolous lawsuits" and "no liability lawsuits at all", which is ridiculous. There are lots of ways one might restrict frivolous lawsuits without outlawing liability lawsuits entirely. For example, "loser pays" legislation would discourage lawsuits with little chance of winning, limiting the number of parties who can be sued for a single event would eliminate farces such as the woman who sued every single store in an entire shopping mall when she slipped and hurt herself, increasing the importance of the "duty to mitigate" (so that the plaintiff's own stupidity is taken into account) would reverse many frivolous lawsuit decisions entirely, and stipulating that all punitive damages (as opposed to tort damages) go to government social programs rather than the plaintiff would reduce the prevalence of the lottery mentality (the company is still punished, but the plaintiff doesn't become rich). There are countless possibilities, all of which he deliberately ignores in favour of the false dilemma.

Burden of Proof

This is the tactic of shifting the burden of proof onto the wrong party. Another version is the assumption that a lack of evidence for side A constituted de facto evidence for side B, even though it was side B that actually bore the burden of proof. For example:

"You can't prove that Earth in Star Trek is not protected by massive shield grids which can withstand orbital bombardment, huge surface weapon emplacements, and orbiting weapon platforms. The fact that we haven't seen them doesn't prove that they don't exist."

"Since you've never actually seen Borg cubes destroyed by a Death Star superlaser, you have no evidence for your claim that they wouldn't be able to adapt to it."

In real life:

"It takes just as much faith to disbelieve in God as to believe in Him, because you can't disprove God's existence any more than I can prove it."

"How can you deny all of the alien abduction stories? You can't seriously tell me that all of the witnesses are lying or delusional. You can't seriously tell me that all of the pictures are faked or inconclusive. You're buying into the Big Lie, and you won't admit that you can't disprove these theories."

In general, the logical principle of parsimony (also referred to as Occam's Razor when discussing the philosophy of science) means that the default condition for a phenomenon is not to believe in its existence. This is a logical and practical policy; if we automatically believe in everything until it is disproven, then we immediately paralyze ourselves because there is quite literally an infinity of ideas which we could invent out of thin air (for example, try to prove that there is no invisible pink unicorn).

In other words, belief in any phenomenon is a positive condition which must be justified, ie- the burden of proof falls upon the person claiming the existence of a phenomenon, not the person denying it. Let's apply that principle to the above examples:

The first Star Wars example is pretty straight-forward; it is unreasonable to demand that someone prove that things we've never seen do not exist. It's true that we have no absolute proof of their nonexistence, but we must choose the most logical conclusion in this situation, and that is "no massive planetary defenses". We cannot assume their existence without some kind of positive evidence. The second Star Wars example is a bit more convoluted: he tries to turn the situation upside down. Borg adaptation technology with limitless capabilities is an absurd idea, yet he expects us to accept it as a default condition, thus demanding that we accept the burden of proof to show that it is not limitless!

The first real-life example is a classic religionist ploy. However, the logical principle of parsimony means that when faced a lack of evidence either way, the most logical conclusion is that it does not exist. In other words, the burden of proof is on anyone who would claim that God does exist (that's why honest Christians admit that they have nothing but their faith, while the idiots and liars try to pretend that their belief system is no less logical than an atheist's conclusions). The second real-life example is another unfortunate but common ploy: he acts as though we should assume the existence of a patently absurd phenomenon: interstellar travellers who would travel dozens, perhaps thousands of light years (an act which might not even be physically possible), only to mutilate cows and abduct people from trailer parks! As the old saying goes, extraordinary claims require extraordinary evidence (certainly much more than appeals to popularity or laughably grainy pictures), yet he puts the onus on us to disprove them.


A tautology is a statement which is technically true, but which says nothing of substance. It is redundant, useless, and often repeated ad nauseum, like a mantra. Technically speaking, this is a dishonest rhetorical technique rather than a logical fallacy, but I include it here simply because, well, I don't want to make a whole separate page for dishonest rhetorical techniques. For example:

"It is impossible to know for sure what would happen in a Star Wars versus Star Trek matchup, unless Lucasfilm and Paramount get together to make one."

"Star Wars and Star Trek aren't real."

And in real life:

"Unless you go back in time four billion years, it's impossible to know exactly what happened at the birth of life on this planet. All you have is theories."

"Guns don't kill people, people kill people."

In the first Star Wars example, the person states the obvious: we will never know for sure. However, that doesn't matter. Real scientists don't know for sure; they have only logic and observations, and that's good enough. While philosophers waste time seeking the impossible (absolute knowledge of truth), scientists are busy cataloguing their observations and the logical conclusions which flow from them. Similarly, we have no way of knowing "for sure" what would happen in a Star Wars versus Star Trek matchup, but we can derive logical theories from the evidence at hand. The person who participates in the debate and then complains about the lack of absolute knowledge is merely crying sour grapes; the logic and evidence don't add up to what he would like, so like a petulant child, he stomps out of the game and whines that it's a dumb game anyway. In the second Star Wars example, the person makes a statement which is utterly useless. OK, so they aren't real; so what? How do we know the real universe is real? Maybe you're hooked up to an elaborate virtual reality simulation, and the entire world is just a figment of your imagination! The point is not whether they are real, but whether it is possible to treat them as if they are.

In the first real-life example, the creationist complains that no matter how much evidence we dredge up, no matter how logical our conclusions are, we cannot know for sure. And that's true; we cannot know for sure. However, we can easily determine which of the two theories (evolution or creation) is better. And that's the real question: which one is most logical? Which one most closely fits the evidence? Creationists try to distract you from the inferiority of their "theory" by simply pointing out that their competitor isn't perfect, even though their own theory is far, far worse. In the second real-life example, we hear another statement which is technically true; without a human operator, a gun is harmless. However, that has nothing to do with the gun control debate, because the guns in question do have human operators. The debate is over human behaviour (does the criminal deterrent effect of private firearms outweigh the increased lethality that cheap, available handguns bring to stupid, random acts of drug-induced, alcohol-induced, or rage-induced violence?), not the silly question of whether a gun can kill someone without a human to pull the trigger. If someone opposed nuclear arms treaties by saying "nuclear weapons don't kill people, governments kill people", it would be considered absolutely preposterous, but for some reason, the same tautology scaled down to the individual level strikes many people as perfectly sound.

Golden Mean

The Golden Mean fallacy assumes that given two opposing viewpoints, the correct solution is invariably the middle, or "golden mean".

"You always have Star Wars crunching Star Trek in every matchup, every scenario, every conceivable way. How realistic is that? Your position is ridiculously extreme and can't be taken seriously. A more reasonable person would recognize some of Trek's advantages. Both sides have their advantages and disadvantages, so it evens out."

In real life:

"Creationists and evolutionists are the two extremes, and both sides are equally dogmatic and close-minded. I think that if each side were to step back and look at this objectively, they would realize that. I think there's too much evidence to deny evolution, but at the same time, the creationists make a lot of good points in favour of intelligent design."

The Golden Mean fallacy is based upon the common belief that neither of two diametrically opposed viewpoints can possibly be correct (possibly an offshoot of the political correctness movement, in which people are no longer permitted to make unambiguous statements). But why? Why can't one of two opposing viewpoints be correct? No one can ever say; the Golden Mean fallacy is a rhetorical technique, not a legitimate logical argument. In fact, the Golden Mean is one of the most popular rhetorical techniques: a particularly infuriating political technique is to exaggerate one's position beyond all reason, which effectively pulls the "golden mean" towards your side. For example, the creationist movement needs its wacko young-Earth Southern idiot contingent, because it makes their "intelligent designer" position suddenly seem quite reasonable by comparison.

In the Star Wars example, he tries to portray my position as "extreme", and compares it to the ridiculous Trekkie position that their tiny organization could stand up to an Empire with thousands of times their numbers, speed, and firepower. Since their position is so far away from mine, the most "reasonable" answer must be somewhere in the middle, right? And in the creationist example, he tries to portray both sides as equally "dogmatic" without a shred of evidence (indeed, one can easily show that creationism is dogmatic while science is not, since creationism relies upon an unchanging doctrine while science continually improves and changes as we learn more about the natural universe). In any case, he uses the sheer distance between the two camps as proof that both are wrong, without bothering to produce any real evidence or argument.

Style over Substance

The Style over Substance fallacy is based upon the sadly common belief that the manner in which one makes his argument somehow affects the truth of that argument. For example:

"Your use of foul language is all the indication I need of your personality type. I don't see how you can expect anyone to take any of your arguments seriously when you express them in such a manner."

I hope you understand what's wrong with this argument, but in case you need clarification, imagine the following hypothetical exchange:

Dave: "Hey John, I saw your baby crawling around in the back of your car. Where's your child seat?"

John: "I don't have one, and I don't plan on getting one. Mind your own business."

Dave: "What the fuck is wrong with you, asshole? Don't you realize that a baby who's not in a car seat will be launched like a fucking missile if you have an accident? Jesus H Christ, don't you care if your kid lives or dies?"

John: "How dare you use such language in front of my child?"

Dave: "How dare you risk your kid's life, shithead? Is it really so goddamned important to save fifty fucking bucks on a child seat? Would it kill you to spend five seconds strapping him in?"

John: "I don't have to take this kind of abuse. You need to learn some manners."

Now, here's the big question: does Dave have a point? Is his argument wrong because of his rude and confrontational manner? In a word, no. The use or disuse of "foul language" has no bearing whatsoever on the validity of his argument.

Is it bad for Dave to be so confrontational? Maybe, and maybe not. After all, John has already ignored all manner of politely worded public service announcements, and he may have also ignored numerous polite suggestions from other relatives and acquaintances, so at this point, what's to lose? But regardless of whether you agree with Dave's choice of words, the fact remains that he is right, and John is wrong.

Red Herring

The red herring is an irrelevant subject, usually introduced in an attempt to drive the argument away from its original subject.

"You say that the Empire would win because of its speed, firepower, and numbers. I'll grant that those are impressive strengths, but you forgot about one thing: Q."

"You claim that the Death Star pumps some godawful huge amount of energy into Alderaan, but if so, how did it generate this power? Where's all the fuel storage? How does the beam work? You have no answers, do you? And if you don't know the answers to these simple questions, then how can you say how much energy it produces?"

And in real life:

"You say that the Second Law of Thermodynamics doesn't disprove evolution because of that open/closed system thing, but you forgot about one thing: the universe is a closed system. With all your hot air about scientific accuracy, I find it amazing that you let that slip by you."

"How can you say that it's a freedom of speech issue to lift the publication ban on DVD encryption information? You seem to have forgotten the issue of intellectual property, and the rights of copyright holders. How are movie studios supposed to make any money if they can't stop rampant piracy?"

The Red Herring fallacy is an evasion tactic. Its most common form is the much-reviled "nitpick", in which someone tries to look for imperfections in the minutae, the wording, or perhaps even the spelling of an opponent's argument in the hopes of making the debate revolve around those imperfections rather than his opponent's main point. It's OK to mention such minutae in passing, but only if one keeps the focus squarely on the original point.

In the first Star Wars example, Q is a red herring. The Empire's strategic and tactical superiority is not affected by the presence of Q. Of course, if we make the point that Q is a red herring, our opponent will swiftly switch into red-herring justification mode. He will try to claim that Q is actually beholden to the Federation somehow and so he will ride to the rescue. But this is merely the second part of the red herring fallacy: first you introduce the red herring, and then you use it to distract people from the original debate. In the second Star Wars example, the power of the Death Star is established by a simple thermodynamic "state comparison". The energy state of Alderaan after the blast is compared to its state before the blast, and we simply take the difference. It is irrelevant how the Death Star accomplishes this feat, just as nuclear fusion was irrelevant when scientists first began to quantify the Sun's radiation output; even though they didn't know how it worked, they could still figure out how much power it made.

In the first real-life example, the fact that the entire universe is a closed system does not mean that an individual life form is a closed system, nor does it have any bearing whatsoever on the fact that the Second Law of Thermodynamics is not violated if the entropy level drops in a particular life form (note that this is just one of a huge list of problems with the idiotic creationist Second Law of Thermodynamics argument). In the second real-life example, the question of copyright holder's intellectual property rights is completely irrelevant to the question of whether a publication ban on information relating to DVD encryption violates freedom of speech. If Big Brother decides that freedom of speech is less important than intellectual property rights and that there is no way to reduce piracy other than trampling on constitutional rights, then that might empower the jack-booted thu- er, lawmakers to enforce the ban anyway, but that decision has no bearing on the question of whether freedom of speech has, in fact, been violated.

Slippery Slope

The slippery slope fallacy is based on the idea that once you take the first step down a path, you will be inexorably drawn down that path until you reach an inevitable and very bad end.

"You shouldn't criticize Picard's defense of the Ba'ku in STI. If the Ba'ku were forcibly moved and their property rights violated, no matter how many billions it would have saved, it would have been immoral. Once you let the government take away property rights, what's next? Freedom of speech? Civil rights? That way lies totalitarianism, human experimentation, ethnic cleansing, and barbarism."

"You shouldn't criticize the Prime Directive. Yes, it may seem immoral to stand idly by while an entire civilization is destroyed. But if we intervene to stop a natural disaster, what's next? Will we step in to stop disease? Will we step in to stop a war? Will we step in to 'bring civilization to the savages', the way the Europeans did in their bloody expansion phase? Where do you draw the line? You know where this road leads, don't you? Ruthless imperialism!"

And in real life:

"If you take away federal funding for this artist's sculptures of pedophiles molesting children, then you are using government money to reward a preference for certain types of art. This is social engineering, and it starts us down the path to an Orwellian nightmare where thought police control our lives. Therefore, you must give this artist federal money to make his pedophile sculptures."

"If the government wants to license firearms, then we all know what the next step is: the police will be knocking on your door to take your handguns away. If they take away your handguns, then the next step is to take away long guns too. Once they've taken away long guns, the next step is a police state, and a totalitarian dictatorship. Therefore, there should be no firearms licensing."

Whenever someone says "where do you draw the line", you're probably dealing with a slippery slope artist. There's nothing wrong with picking a spot and drawing the line there, rather than creating a false dilemma and forcing us to choose between two extremes. If you're still unsure about the slippery slope, click here for more detail.


The Strawman fallacy is to attack a distorted, weaker version of your opponent's argument. In the more egregious cases, a strawman is a complete fabrication which bears no resemblance whatsoever to the argument in question. For example:

"You seem to feel Imperial ships would be completely invincible. That just demonstrates the extremist, and illogical nature of your arguments. No ship is ever invincible, and the fact that you would even suggest such a thing tells me that you are a fanatic."

[In response to a logical rebuttal written in an insulting tone] "You're pretty good at insults, but it's a lot harder to debate logically. By insulting me rather than dealing with my argument, you have essentially admtted defeat."

In real life:

"If species come from evolution, then why don't we ever see one species turn into another? Why don't birds turn into cats, for example? And if life came from random chemical reactions, then how do you explain the complexity of the simplest bacteria? The odds of even the simplest bacteria forming from inanimate material are astronomical!"

"Senator Jones would have us reduce the proposed Medicare spending increase by twenty percent. Ladies and gentlemen, we can hardly afford to slash twenty percent from Medicare! What would be left? What will Senator Jones say to the disadvantaged children of America when they can't get their vaccinations?"

In the first Star Wars example, our opponent tries to distort "more powerful than Federation ships" into "invincibie", thus generating a nice strawman for his convenience. In the second example, our opponent ignores a logical rebuttal because it was written in an insulting manner, and pretends that we are committing an ad hominem fallacy (note that an insulting but logical rebuttal is not an ad hominem fallacy, because it still addresses the point rather than ignoring the point in favour of the man).

In the first real-life example, the creationist claims that evolution describes one species magically transforming into another, even though it does not. He goes on to claim that abiogenesis involved the sudden appearance of a fully formed bacterium, when the first organic self-replicator is theorized to have been a small piece of RNA molecule, not a full-blown bacterium. In the second real-life example, a reduction in the size of an increase is described as "slashing" the budget, which is a gross misrepresentation of the facts. A 20% smaller increase is still an increase! This kind of rhetoric is very common in the political arena; here in Canada, we have repeatedly witnessed the absurd spectacle of civil servants screaming that the government is "stealing" from them by giving them a smaller pay raise than they demanded.

Hasty Generalization

The hasty generalization is the use of an unacceptably small sample as the basis of a conclusion about the larger population.

"Stormtroopers can't aim! The stormtroopers in the ANH docking bay missed Luke Skywalker by a mile, and they were assigned to the Death Star so they must have been elite troops."

"The Federation found a way to overcome the numerical and technological superiority of the Dominion, and even the Borg. Therefore, they are very good at overcoming older, bigger, more advanced enemies, so they'll be able to destroy the Empire."

And some real life examples:

"Whenever I watch COPS, I see a lot of black people getting arrested. Therefore, black people are inherently prone to criminal behaviour."

"I don't know why you make such a big fuss about stop signs. I've been driving through stop signs for years, and I haven't had an accident yet."

In the first Star Wars example, the person tries to generalize about millions of stormtroopers based on a dozen. The sample size is totally inadequate, and the resulting conclusion is invalidated by the fact that stormtroopers have good accuracy in other parts of the trilogy (the boarding of the blockade runner in the beginning of ANH, the blast points on the Jawa sandcrawler, the hits to Leia and R2D2 in the Endor forest battle. It also ignores the possibility (probability?) that the stormtroopers in ANH (and perhaps also TESB) were under orders to herd and harass the Rebels without killing them (Vader wanted them to escape in ANH with the planted homing beacon, and he wanted them to rescue Luke in TESB). The "elite troops" bit is another fallacy (leap in logic, see below), because the Death Star assignment doesn't necessarily indicate elite status. In fact, since the Death Star has millions of troopers and was not expected to ever be boarded, it seems more likely that the reverse is true: the Death Star troopers were probably not elite troops. In the second Star Wars example, the person makes the utterly absurd argument that since the Federation defeated two superior enemies (the Dominion with a lot of help, the Borg thanks to their staggering stupidity), they must be capable of defeating all superior enemies.

In the first real-life example, the person assumes that the criminals he sees on COPS are representative of the entire black race and must therefore indicate some kind of intrinsic criminal tendency (the hasty generalization is the underpinning of most racist attitudes). In the second real-life example (which unfortunately comes from an actual person I've met), the person assumes that a number of successful stop-sign violations over a period of several years constitutes proof that stop signs can always be ignored, even though it was undoubtedly simple odds and the awareness of other drivers which kept him out of the accident he so richly deserved.

Leap in Logic

The leap in logic jumps from A to B even though there is no connecting linkage between the two. Also known as "non sequitur", ie- "does not follow".

"We have seen that the Federation can build hundreds of starships, so they can obviously build moon-sized planet-destroying battlestations. They just choose not to, because they're not as warlike as the Empire."

"The Borg are undoubtedly capable of building massive superweapons beyond anything the Empire has ever constructed, because of their rapid-replicating technology. Look at how quickly they can assimilate a starship!"

"The Borg can adapt to a Death Star superlaser because we've seen cubes adapt to the weaponry of the Enterprise, and we've seen drones adapt to hand phasers."

And some real-life examples:

"During the last hundred years, we've made some amazing advances in technology. Therefore, nothing is impossible."

"The latest astronomical observations indicate that the universe is expanding too quickly to slow down and contract from gravitational attraction. Therefore, the universe is not in an endless cycle of expansion and contraction. Therefore, it had a beginning. Therefore, it must have been created. Therefore, there is a God."

"McDonald's is the most popular restaurant in the world. Therefore, it is the best."

The leap in logic is amazingly common, although to be fair, it is sometimes the case that there is a connecting link, but it is so obvious to the debater that he didn't think it required explanation. For example, one who is familiar with grade-school science may consider the link between mechanical stress and mechanical failure to be self-evident (although some do not find it obvious- see IXJac on my Hate Mail page). However, whenever the cause and effect relationship is not obvious, one must explain it. At the very least, one must be prepared to do so if challenged, but it is surprising how many people will refuse to do so.

Let's look at the Star Wars examples first:

  1. Our opponent leaps from "build hundreds of small starships" to "build giant moon-sized planet-destroying battle station". However, the ability to construct a small object does not necessarily denote the ability to construct an arbitrarily large object! There are serious structural problems inherent to large structures, and a moon-sized structure would present incredibly difficult engineering problems long before the first girders are welded into place. Worse yet, the sheer quantity of material would be overwhelming, and the power output would be well beyond their capabilities; the Federation would have to be able to increase its industrial output and volume-specific power output by millions of times!

  2. Our opponent leaps from "rapidly assimilate a small starship" to "construct vast superweapons of apocalyptic power". It's almost as if he's saying "they work fast, so they can do anything". What's the connection? It isn't enough to simply describe A and B and then assume that one leads to the other; why should we make that connection?

  3. Our opponent leaps from "adapt to a single ship's weapons" and "adapt to hand phaser" all the way to "adapt to planet-destroying superlaser with millions of times the power output of the Sun". This is tantamount to claiming that since a tank's armour can survive small-arms fire and shells from certain types of artillery, then it should be able to withstand a direct hit from a huge, falling asteroid.

Now, let's look at the real-life examples:

  1. Our opponent leaps from "achieve technological advancements" to "omnipotence is within our grasp", which is so absurd that it borders on megalomania.

  2. Our opponent makes an absurd leap from "the universe had a beginning" to "it must have been created by God". Why couldn't it always have existed, since time would not have passed before the Big Bang? Why couldn't it have been produced by natural processes in some other universe? Why must we leap to the conclusion that some sentient, omnipotent being created it out of his thoughts?

  3. Our opponent leaps from the popularity of McDonald's to quality, even though the popularity of McDonald's could very well be due to any number of other factors (convenience being chief among them).

Typically, when faced with arguments like this, we are expected to painstakingly disprove them (this is the basis of the O.J. Simpson defense; pepper your opponent with a horde of unsupported arguments in order to bewilder, overwhelm, and generate confusion and doubt). However, we should not have to disprove a connection between A and B when our opponent has failed to establish the connection in the first place!

Stolen Concept

The stolen concept fallacy is the use of concepts while rejecting their supporting logic. In effect, the debater attempts to "have his cake and eat it too", by simultaneously using and rejecting an argument.

"According to Mike Wong's website, Deja Q proves that a Federation warp core can generate at least 30,000 TW. I agree with his reasoning in that case, but when it comes to Death Star firepower, he's completely out to lunch. You can't apply scientific methods to visual effects."

<Any and all pseudoscientific arguments from Gothmog, Graham Kennedy, or the rest of the "science doesn't apply to sci-fi" crowd>

And some real-life examples:

"We have found samples of granite in which polonium halos are visible1. Since halos can only form in solid rock, and the half-lives of Po-218 and Po-214 are less than four minutes combined, the rock must have solidified almost instantly, rather than cooling from magma over millions of years as the evolutionists claim. The only possible explanation is that it was created through supernatural means by a Supreme Being. He must have created the rock with polonium inclusions in place, in order to create the halos. This conclusively disproves uranium/lead radiometric dating techniques that show a geologic timescale of billions of years."

"The latest research in zero-point field quantum physics shows that it is possible to make a perpetual motion machine, and that the first law of thermodynamics does not apply in the quantum domain."

The stolen concept fallacy is particularly annoying because it betrays a fundamentally dishonest mindset. The person who uses this kind of argument is not interested in constructing logically self-consistent arguments or conducting serious investigations; he simply picks and chooses bits and pieces of various contradictory arguments and assembles them like mismatched bricks, with nothing but rhetorical flourishes and quasi-religious fervour to hold them together.

Let's look at the Star Wars examples first:

  1. My analysis of Deja Q is based on the application of scientific principles to the visual effects of that particular episode. He accepts the conclusion, yet he turns around and categorically rejects the underlying method because it produces results which annoy him when it is applied to the Death Star.

  2. Over the course of several years, I have never once encountered a member of the "science doesn't apply to sci-fi" Trekkie crowd who consistently applied that philosophy (or provided a valid justification for it, since their arguments against science in sci-fi are identical to fallacious creationist arguments against science in real life). They're perfectly happy to apply E=mc² to the yield of an antimatter blast, the effects of heat and stress to structural failures, the principles of specific heat and mass/energy conservation to the work requirement for melting metal, etc., but they turn around and deny all these concepts when they produce results which annoy them.

Now, let's look at the real-life examples:

  1. One could go blue in the face listing the errors in the "polonium halo" argument. It fails to state its hidden assumption (that all of the granites on the Earth formed at the same time as the Earth), it employs a fallacious leap in logic from "unsolved mystery" to "supernatural creation", it treats geology and evolution theory as one conjoined concept, and it contains not one, but two exampes of the stolen concept fallacy. The first instance of the stolen concept fallacy comes when it employs several nuclear physics principles while rejecting the scientific method which was used to derive those principles2 (by proposing a hypothesis without genuine predictive capabilities). The second instance of the stolen concept fallacy comes when it employs a subset of the methods of uranium/lead radiometric dating (even going so far as to use the same decay chain!) in order to "prove" that the Earth is young and that the methods of uranium/lead radiometric dating are wrong. The person who makes this argument makes no effort to be consistent; if uranium/lead radiometric dating is conceptually wrong, then he can't use it to "prove" that the Earth is young. If, on the other hand, it is conceptually valid, then he must find a way to rationalize the polonium halos with the geologic timescale. This is hardly difficult to do, since the polonium halos are only found in very specific regions (coincidentally near uranium deposits), there are a variety of subterranean geological processes which can form young rocks on an old planet, and granite can form through composition rather than solidification from magma. However, he can not simultaneously argue that the method does not work and then shamelessly use it in order to generate his own "proofs"!

  2. Zero-point field theories incorporate conservation of mass/energy as an assumption. Therefore, it is impossible to use those theories in order to disprove conservation of mass/energy since they would disprove themselves in the process! If it could be shown that zero-point theories allow violations of thermodynamics, this would only mean that zero-point theories are logically inconsistent, or that they have been misinterpreted.

The stolen concept fallacy is beloved by pseudoscientists around the world, since it basically sums up their entire mentality. The fact that it is a fallacy is completely lost on them, but anyone who would shamelessly use a concept while rejecting its basis is obviously not interested in avoiding fallacies.


1U-238 decays to Pb-206 over 8 stages, three of which are Po-218, Po-214, and Po-210. Dr. Robert Gentry (whose doctorate is actually not in physics, but who nonetheless seems reasonably competent in initial method, if not in conclusion and hypothesis) found alpha decay rings indicative of polonium in granites from a few selected sites in which the decay rings indicative of its precursors were not present. Alpha radiation leaves characteristic halo patterns as it damages surrounding rock, but the rock must obviously be solid in order for this damage to be preserved over time.

2By way of explanation, the scientific method demands that rational hypotheses be made, and that a valid theory have predictive capabilities. The idea of a Supreme Being is not a rational hypothesis (rather than explain the phenomenon, it simply gives up and claims that rational explanation is impossible), and it has no predictive capabilities. Some might argue that it predicts the polonium halos, but that is blatantly untrue. If one starts from the idea that a supernatural, inscrutable Supreme Being created the Earth, there is no logical means through which one can possibly arrive at the prediction that he would choose to put short-lived polonium inclusions within primordial granite. Indeed, a supernatural being could have created these "halos" without using natural mechanisms such as polonium decay. In the end, Gentry has only shown that at one time, there were polonium deposits in solid granite. He has not proven that the Earth is young or that its formation required supernatural intervention.

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