Memories of the 28th Century

Or
Logical fallacies for humor and for destroying arguments



For the last couple of decades I have wasted a huge amount of time on online forums and such. I have found myself in illogical discussions frequently, because people often use logical fallacies. I can accept that now and then; most people use fallacious reasoning on occasion, sometimes deliberately and sometimes in ignorance; but many people don't even notice their fallacies when the fallacies are pointed out. I will admit that some logical fallacies are not obvious, but the most common fallacies are quite clear.

An excellent example of a non-obvious fallacy is argumentum ab auctoritate, argument from authority. This is a claim that some authority says such and such, so it must be true. It is valid to cite sources for one's conclusions, but a citation is not proof. Several citations might be telling, but there are many sources that could be put up that are not truly authoritative. I recently broke off a discussion of nutritional claims for this reason. There are many people who make false claims about foods. Fundamentally, appealing to an authority is a red herring; the argument should stand on its own, but here should be authoritative evidence.

Another variety of argumentum ab auctoritate is using a false authority. This is often used in religious arguments, where the Bible, Koran, or another religious text is put forth as authoritative. Religious arguments also typically beg the question; assume that the matter being debated is true.

This is close kin to false attribution and quoting out of context. Claiming that a mutually agreed upon authority said something that he did not is rare, but it can be relatively clever. I recall that Mark Twain recounted the use of this to shut up a boor on a voyage to Hawaii. Quoting out of context is all too common, and it isn't always immediately obvious, but the authority has to be agreed upon for this to be effective.

One class of fallacy is the red herring, and there are several different fallacies within this class, from simply changing the subject to argumentum ad hominem, argument at the man; this is an attack on the other person, rather than at the person's argument. This can be quite impersonal in aspect, simply a comment that the person has not done his research, or it can be an assertion like: "You don't even have the vaguest clue about ..." It is valid to point out that specific items are in error, but an assertion that someone does not "have the vaguest clue about" anything is an attack on the person, and it is almost certainly incorrect. There are valid and reasonable ways to point out someone's ignorance, but it can look like argumentum ab auctoritate, so care should be taken. When I encounter anything that smacks of ad hominem, I try to drop the discussion, because it can lead to more nastiness. When someone has no argument in fact or logic, the illogical person will change that subject.

There are other ways to change the subject including argumentum ad baculum, appeal to the stick, a threat of force. Argumentum ad populum, appeal to the people, is an appeal to widespread belief. And there are many other types. The funniest version of red herring in argument is to simply start discussing something else. That sounds ridiculous, but it happens frequently, and sometimes it is a good idea; it certainly is better than having someone take a swing at you.

Another popular fallacy is Argumentum verbosium, argument by verbosity, which is trying to overwhelm an opponent by throwing lots of words out. I usually avoid these by not reading exceptionally long posts.

Post hoc ergo propter hoc, after this therefore because of this, is very popular, but it is frequently not noticed, because many people think it is a scientific principle. Similarly, ignoring cause and effect entirely is a common fallacy.

A related fallacy is the Gambler's Fallacy, the incorrect belief that separate, independent events can affect the likelihood of another random event. If a flipped lands on heads 10 times in a row, the belief that it is "due to the number of times it had previously landed on tails" is incorrect. I remember having someone who was taking a course in probability who made this mistake. On the other hand, there are no completely random events, but there are events that are not related in ways that are likely to affect another event, and serial flipping of a coin is one.

Then there's the matter of assigning causes to one event that are not related to that event, but I will confess that it is difficult to tell whether a cause is related to a specific events, and perceptions do vary.

Another favorite fallacy is thinking that the absence of evidence for something proves the thing does not exist. If there are no people in a certain room, that is good evidence that there are no people in that room, but it is not evidence that there are no people in a different room.

If you spend any great amount of time online, then I am sure that you have seen these and other logical fallacies. There are many fallacies, and I don't want to list every fallacy here. There are links to two lists of fallacies at the bottom of this page. It is a good idea to avoid logical fallacies; not only will they ruin your argument, but they may lead you to believe things that are simply not true. Then there's the matter of the logic of advertising, but that's the subject for another post.



Two sites the list common logical fallacies. There are many more sites that have instructions in logic, just search.
https://owl.english.purdue.edu/owl/resource/659/03/
http://www.nobeliefs.com/fallacies.htm