How to make online debates interesting – for everyone

'Hollow' arguments made in favour of whaling on our forum

Have you ever noticed how on some forums the debate always ends up as a personal slanging match? This can kill a forum as it puts off newcomers. Eventually, even those who are interested give up trying to have a serious debate. The bottom line is, no-one really cares about your personal vendettas or the outcome of your epic battles. At best, they just find it amusing to watch people wind themselves up.

There are two main causes of this. If the moderators fail to enforce a reasonable code of conduct, or they show bias in the enforcement of it, then heated arguments will be inevitable. However, even if members mean well they can still end up in pointless battles because they are unfamiliar with a few common ‘logical fallacies.’ These are common lines of argument that appear to make sense on the surface, but are based on false assumptions and ignorance. I will outline the more common ones below.

If people do not realise that an opponent is using a logical fallacy, they tend to use the same argument to back up their point of view, then put considerable effort into finding ‘evidence’ to back up this argument, even though it doesn’t make sense. Either that, or they put considerable mental effort into countering an argument. This effort can make the argument appear even stronger by suggesting that it has some merit and is difficult to counter. Trolls take advantage of these situations – effectively taking advantage of people’s ignorance – because they are a shortcut to a heated debate.

Logical fallacies are often referred to by their latin name. Not only does this make you appear smarter than everyone else, it also saves a lot of time. For example, by simply passing of your opponents argument as an ad hominem, you are in effect saying that your opponent has failed to make a rational argument that is worth responding to. When people use these fallacies persistently, it can save a lot of effort to just drop the term, as you can avoid a lengthy argument with a fool. It also helps avoid the impression that you are just complaining about being called names and that you can’t stand the heat. Unfortunately, not everyone is familiar with these terms, so to avoid confusion (and sounding like a pratt), please refer people to this article if you are not familiar with them and think they may not understand you.

If an argument seems to go on forever even though it doesn't get personal, it is probably a result of failure to consider the assumptions (premises) behind each argument. People usually realise when a discussion has become pointless as it tends to get repetitive. At this point they often 'agree to disagree.' If the different sets of assumptions have been acknowledged and both are valid (ie, neither can be shown to be flawed) there is little point continuing. If the debate comes up again the participants can simply acknowledge the different assumptions rather than entering into another lengthy argument. Alternatively, people often 'agree to disagree' because they can't be bothered getting to the root of the disagreement. Many people fear this sort of scrutiny of their beliefs. If this is the case, the debate is likely to reappear and continue at a later date. Either that, or it can lead to the establishment of 'taboo' subjects, which are an interesting trap for newcomers. This outcome is more likely if the subject is not the main focus of the forum. Religion is a common taboo.

ad hominem

"You are an idiot, therefore you are wrong."

An ad hominem (short for argumentum ad hominem) is a personal attack. It is by far the most common logical fallacy encountered in online forums. It carries the assumption that by discrediting your opponent, you are also discrediting their argument. However, this would lead to the absurd situation that an argument is correct if one person uses it, and false if another uses it. Inexperienced debaters often fall for this and feel the need to defend their reputation against a troll, otherwise it will invalidate the point they are trying to make in the eyes of others.

An ad hominem is not always a logical fallacy. For example, if someone claims that their point of view on a technical issue carries more weight because they are a scientist then it would be reasonable to point out that they did not complete their PhD. It would not be reasonable to point out that they are divorced, or a socialist.

Merely insulting someone is not technically an ad hominem unless it is done in a way that discredits their argument – however, it is still inappropriate.

The opposite fallacy to ad hominem is ‘appeal to authority,’ claiming that the good qualities of a person making an argument support that argument.

argumentum ad populum

“Everyone agrees with me, therefore I am right.”

This is frequently encountered by newcomers to a community of like minded people. Lots of members agree with their opponent, and their opponent claims that this is evidence that he is right. Alternatively, people can create ‘sock puppets,’ which are multiple accounts used to create the impression that others agree with them. Large corporations often create ‘dummy’ activist groups to make it look like there is grassroots support for their actions (also known as shilling or astro-turfing).

This argument is often used implicitly when people quote poll results on an issue. It can be extended to claim that because a person lives in a democracy (or even the ‘best democracy in the world’) that the policies of its government are correct.

This is also a ‘non-sequitor.’ that is, it just doesn’t follow. Living in a democracy does not mean that government policy is ‘correct.’ It is also the ‘fallacy of the single cause.’


This term is probably a reference to the middle ages, when people would build scarecrows stuffed with straw to use for military training. Strawmen are easy to defeat. In debates, people will often misrepresent the argument of their opposition, then gleefully shoot it down. Rather than explaining yourself again, just call it for what it is (provided of course you explained yourself clearly the first time).

People can set up sock puppets to pose as straw men. That is, creating a profile that disagrees with you, but makes such a poor argument that you ‘win’ the debate. Then you can point out to your detractors that you have already shown their argument to be lacking. You can even let someone else do the refuting, and just pass yourself of as ‘the enemy’ – a particularly stupid one.

McDonalds has made very good use of straw men in its recent advertising campaign where it 'debunks' a lot of the criticism made against its 'food'. For example, they debunk the myth that they're burgers are not 100% beef (ie, no car parts or fertiliser), without addressing in any meaningful way the real issue of the fat content and quality of that beef.

false dichotomy

"If you don't agree with me, then you obviously believe this..."

This is similar to a strawman, but relies on a false assumption that there are only two choices on an issue. Those two choices can be general descriptions for the extremes of a continuum of views, or a simplification of a multidimensional issue (eg left vs right wing). A false dichotomy is often implicit in an argument that attempts to support a view by attacking an alternate view or comparing it with an alternate view. Other examples: "you are either with us or against us," "you don't support unregulated free market capitalism so you must be a communist," "you don't believe in evolution so you are a creationist."

appeal to emotion

This fallacy often crops up when discussing the cause of a disease or some other unfortunate situation. People will try to argue that those suffering are not responsible for the situation, or that something else (a company, a government, a chemical) is, by appealing to sympathy for the victims. They try to get you to agree with them by laying a guilt trip on you, with the implicit assumption being that you are 'adding salt to the wound' by disagreeing. Even if you are 'adding salt to the wound' that doesn't mean you are wrong or that you should capitulate out of sympathy. Effectively you would be agreeing to lie to people about the cause of their problem, thereby leading others into the same problem.

Appeals to emotion don't always rely on guilt or sympathy. For example someone can try to flatter you by telling you that you are smart or gifted because you are going along with them.

As an example, the peculiar fondness for 'battlers' that is so strong in Australian culture is getting in the way of progress towards sustainability by stigmatising those who point out the damage done by European farming practices to our environment or who suggest that farmers should be the first to cut back on water consumption during a drought merely because they use most of it and pay the least for it. It has led our society to prop up unsustainable farming practices rather than allowing farmers to be forced to adapt to changing conditions.

argumentum ad consequentiam

If you are correct we are doomed, therefore you must be wrong.

An appeal to consequences is a form of appeal to emotion. It is an appeal to fear of the negative consequences of being correct. This one crops in most often in arguments about religion, with the implication being that because of the positive outcomes of religion, it must be true. The argument usually takes the form of the corollary - that an alternate world view must be wrong because its consequences could be bad (eg leading inevitably to nihilism). From a logical perspective, this can be a valid reason not to discuss the matter if communal self delusion can avoid the negative consequences, though it is not a valid criticism of the argument itself. In more mundane situations the negative consequences are usually inevitable regardless of whether people believe it is coming. That is, they are the result of external factors rather than the result of a change in belief. In this situation self delusion is likely to worsen the consequences. For example, I have seen this argument used by fishermen to discourage discussion of the threats to a fishery and even to argue that someone promoting awareness of those threats must be wrong, because they do not like the solutions that are being offered.

reversing or misusing a correlation

90% of white people fall for this, so if you are white you should read this. I have pointed this fallacy out to some people repeatedly, but it rarely sinks in. As a simple example, imagine a man discovers that his daughter’s new boyfriend has a tattoo. He could point out that 95% percent of prison inmates have tattoos, which is technically correct. However, he would be hoping that his daughter would misinterpret this to mean that 95% of people with tattoos have been to prison.

correlation equals causation

This is a difficult one to counter because so many people are ignorant of the meaning of statistics. Even most scientists can have trouble with it. This is the root of the phrase “lies, damned lies and statistics” and is the reason why so many advertisements quote statistics.

Even if 95% of people with tattoos had been to prison, this may not be a reasonable grounds for suspicion, especially in a community where 95% of the population have tattoos. Furthermore, many people misinterpret a correlation whose ‘direction’ is understood correctly, to mean that one thing causes the other, ie that getting a tattoo causes someone to end up in prison, rather than prison life causing many inmates to end up with tattoos. This fallacy causes many problems in science.

This sort of argument is often used by animal liberationists to equate their cause with the fight against domestic violence or high homicide rates. They argue that domestic violence, or ending up in prison, is correlated with pet abuse, with the assumption being that abusing pets causes violence later in life. Taking it even further, they imply that that failing to prevent your child from pulling the wings of flies will cause your child to become a mass murderer, and it will be your fault. Not only is the correlation itself on shaky ground, but there are obvious 'confounding' factors that can cause both. It should come as no surprise that violent men will harm both pets and people, but this does not mean that the violence towards pets causes anything, or that successful animal liberation will prevent violence towards people.

This misinterpretation of statistics adds false weight to the cause of animal liberation. It is so deceptive because it is something that people want to believe. However, it is a double edged sword because it relies on and encourages ignorance – the same ignorance that is partly to blame for sexism, racism and many other ‘isms’. For example, it can often be shown that there is a difference in the average ability of different groups of people. However, this difference is very small compared to the variation within each group and it is foolish to place any weight on it – though it can be a valid explanation for why one group is over-represented at one extreme. However, it is usually a result of historical or cultural factors rather than innate ability or genetic factors.

enemy of your enemy is your friend

This can be a powerful, if dangerous, political tool. However, people often make the mistake of talking up the reputation of a particularly nasty historical figure because they have a common enemy. For example, people may try to argue that Saddam Hussein isn’t really such a bad guy because they vehemently oppose US foreign policy. They attribute the charges against him to some kind of conspiracy by the US, despite all the independent evidence behind it.

association fallacy

eg Some charities have been fraudulent. Therefore charities must be frauds.

absence of evidence is not evidence of absence

The absence of evidence in support of a claim is not necessarily evidence that the claim is wrong. Often it is just that the person you are arguing with does not have the evidence. This can be for a variety of reasons, such as laziness, ignorance, lack of access etc. However, the onus to find evidence should usually fall to the person making the claim.

best available explanation

This is most commonly used by supporters of the theory of evolution against a variety of claims. The fact that it is the 'best available' explanation is subjective to start with. Furthermore, it does not mean that the theory has scientific merit. Given the complete absence of scientific explanations for our origins it is a valueless claim in that context. This line of reasoning could for example be used by UFO enthusiasts to claim that any light in the sky is evidence of UFO's unless their opponent can give a full and immediate account of its cause, much as evolutionists tend to use their ability to explain observations from an evolutionary perspective as evidence for evolution.

reductio ad hitlerum

The reductio ad Hitlerum fallacy is of the form "Adolf Hitler (or the Nazi party) supported X; therefore X must be evil". This fallacy is often effective due to the near-instant condemnation of anything to do with Hitler or the Nazis.

by freediver, 18,20/12/06