When a fallacy isn’t
Last weekend I saw a set of pictures on Instagram with the lead picture containing the headline “The Ten Most Dangerous Logical Fallacies”. The author, Sahil Bloom (author of a book called The Five Types of Wealth), does not explain why they are more dangerous than any other; these are just ten of the best-known or perhaps most common. They include ad hominem, straw man, appeal to authority, false dilemmas, hasty generalisations and the “fallacy fallacy”, i.e. thinking you’ve disproved someone’s argument because you’ve identified a fallacy. He also includes the “sunk cost fallacy”, continuing to expend money or effort on something because of the money or effort already expended, when “smart people” cut their losses; this is a major reason why scam victims continue to engage at their own loss after they start to suspect that they are being scammed, but it’s not relevant to the context in which the other fallacies listed are commonly used. However, the fallacy I want to discuss is “tu quoque” (“and you too”), also known as the “appeal to hypocrisy”, because it is often invoked in contexts in which the argument is in fact quite valid.
Tu quoque is illustrated by a man holding a bottle of beer, telling another man “you are not morally correct because you smoke”. The other man starts to reply “but …”. It’s a trivial example that illustrates how the fallacy works, but it also illustrates why it can sometimes be used validly. Smoking is something people often get addicted to when they are young, because their friends do it and they do it to fit in; tobacco smoke also smells bad to anyone not used to it and both the plant and the smoke contain chemicals which cause a number of diseases, mostly but not exclusively to the smoker. Many smokers nowadays do things to mitigate the effects to others, such as only smoking outside (it is banned in enclosed public spaces in the UK nowadays). Alcohol can also be harmful: it makes people drunk after a glass or two, often too drunk to drive safely, and affects their behaviour, making them uninhibited or violent. Western society considers a moderate drinker to be more “morally correct” than a smoker, but a hard drinker (including someone who might be found drinking at work, as that picture suggests) more of a danger. Someone applying for a sensitive job, such as a teacher, who was a smoker who only smoked outdoors would stand a better chance than a problem drinker, even though the drinker didn’t smell of smoke. (If drinking at all is a sin in your religion, as it is in mine, someone who is known to drink will be excluded from consideration altogether, and may be ostracised.)
And this last point illustrates why this line of argument often is no fallacy. It is a fallacy in a pure, academic moral exercise, but the world is not like that. In the real world, the accuser’s flaws might well be relevant. In an election campaign, for example, a candidate might be making loud criticisms of his opponent’s character but be just as guilty of some of them himself, or of others, and this would directly affect his competence or suitability for the job, so it is entirely valid for the opponent or his supporters to point it out. It might not make the thing he is accused of right, but if the accuser is worse, it might not make him a worse candidate. If a country is gearing up for war, criticisms of their enemy might include that he rigs elections, is corrupt, or is repressive and has people summarily executed or tortured, and the fact that other countries do the same does not make any of those things right either, but if some of those countries are our allies and we are not making any threats towards them, it clearly shows that human rights are not the reason for the war. Whether the war is justified or not, the debate needs to be had, and to be had honestly.
In other contexts, “tu quoque” fails as an argument. When someone is apprehended for a crime, it is no defence to argue that someone else has done the same, or worse, and is not being prosecuted. Sometimes this is fair, sometimes not; if the offence is drug possession, and the person arrested was arrested as a result of a racially-motivated stop and search while people with another skin colour use the same drugs freely, that is obviously unjust and racist, but if the offence is something that causes great harm, like rape, the unfairness is of no importance; taking one rapist off the streets is vital, even if it is in no way preferable to taking off two. It has sometimes been used as a defence in war crimes trials, where officials from the defeated power are tried at the behest of victors who have perpetrated other crimes in other wars, or in their colonial empires, but invariably rejected because the crimes in question were heinous and they were arrested when their attempt to seize their neighbours’ countries failed.
The same set of pictures includes a slide on the “appeal to authority” fallacy and this, too, sometimes has valid uses:
The person uses an expert’s opinion as proof, without any supporting evidence. Experts can inform your thinking, but they generally shouldn’t replace it. People often hide behind credentials when logic runs out.
The problem here is that expert opinion is all that the average person has to go on when talking about things that are beyond their expertise. The average person might assume that one summer is the direct result of man-climate change, or that a cold winter disproves it; they often do not even know what constitutes ‘evidence’ and what is irrelevant. The fact is that the majority of the world’s climate scientists are of the opinion that man-made climate change, caused by burning too much fossil fuel too quickly while destroying the rainforests for logging and farming, is real; to state that is not a fallacy because the authority is real. What is a fallacy is when people cite dissenting studies to explain away a scientific consensus that is inconvenient to them, because it would require them to change their behaviour or might affect their business or other personal circumstances. They will often say “this scientist says …” or “this expert says …” without considering that he is the wrong type of scientist or expert, and is at variance with sometimes an overwhelming majority of qualified scholarly opinion.
In short, there are sometimes good reasons to use arguments that, in an academic context, are fallacies. Sometimes the character of one’s opponent is relevant, sometimes it matters that the accuser is just as guilty as the accused, sometimes it matters that the ‘offending’ behaviour is normal (though sometimes it does not), and sometimes we need to rely on experts rather than our own perceptions; even when the argument is not valid in itself, it does open a window on another injustice. We use arguments not for their own sake, but to advance a cause or to prevent harm being done. The world is not an academic exercise in moral philosophy, and we cannot and should not always behave as if it is.
Image source: Sahil Bloom, via Instagram.


, the Prophet
said:

Tanni Grey-Thompson testing out accessible rail travel in Liverpool