Wishing you all ‘clear thinking’ for the new year
View(s):By Prof. Raveen Hanwella
“Poirot,” I said. “I have been thinking.”
“An admirable exercise my friend. Continue it.”
― -Agatha Christie, Peril at End House
Thus Hercule Poirot, the inimitable detective in Agatha Christie’s stories. advises his friend, the loyal but not so bright Hastings. Our biological name Homo sapiens in Latin means man the thinker. With our superior brain power, man has indeed conquered the world and reigns supreme over all other animals on this planet. But do we think clearly all the time? The appalling mistakes people have made over the centuries would tell us otherwise.
Today I would like to discuss a class of faulty thinking called logical fallacies. The term fallacy is derived from the Latin term fallere meaning ‘deceive.’ A logical fallacy is a flaw in reasoning and in a way are tricks or illusions of thought. They are often used rather sneakily by politicians and media to deceive people.
The first known systematic study of fallacies was done by the Greek philosopher Aristotle. In his book De Sophisticis Elenchis (Sophistical Refutations), an appendix to the Topics, he describes thirteen types. Current classifications describe several hundreds. In this article I will describe a few commonly used types.
The purpose of learning about logical fallacies is not to use them but to learn to spot them. Before going on to describe some fallacies it is important to know what are not fallacies. Factual errors are not fallacies. Some people use the term “fallacy” when they are actually referring to a factual error. For example if someone were to say “some people think that humans are descended from monkeys, but that is a fallacy”, then this would be an error of fact not a fallacy. If a person were to say “Creationism is true because a lot of intelligent people believe in it”, this would be a fallacy. The fact that intelligent people believe in something does not make something necessarily true. Intelligent people can be mistaken. Sometimes things that look like fallacies are not fallacies because they are not arguments (in the technical sense).
Post Hoc, Ergo Propter Hoc
In Latin it means, ‘after this, therefore on account of this.’ It is the fallacy of supposing that if an event follows another the first event caused the second.
In country X after the death penalty was implemented the murder rate has come down. The death penalty is an effective means of reducing murders.
Association does not necessarily mean causation. The murder rate could have reduced due to other reasons such as better law enforcement and improvement in social conditions. This fallacy is often the basis for many superstitions – “when I left the house, a gecko cried and then I had this accident”. The cry of a gecko is considered a bad omen. Ancient historians (and some modern ones as well) such as Herodotus often attributed natural disasters to evil human actions. Sometimes events are just coincidental there has to be more evidence than simply association to say with certainty that one event caused the other.
Hasty generalisation
A visitor on arriving in Colombo, Sri Lanka for the first time says, “It is really warm here, it must be warm in the rest of the country as well.” In reality it is rather cold in the hill country especially in December, and is very hot in the North of the country. This is the fallacy of jumping to conclusions. People commit this fallacy for two reasons. Either the sample is too small or even if the sample is large it is not representative of the entire class. If you toss a coin there is a 50 percent chance it will land ‘tails’ and a 50 percent chance it will land ‘heads’. But this would be true only if we toss the coin hundreds or even thousands of times. Even then it might not be exactly equal.
Appeal to ignorance:"You can't prove that there aren't Martians living under the surface of Mars, so it is reasonable for me to believe there are. It does not however mean that one cannot have good reasons for thinking that something does not exist." Pic courtesy Reuters
Ad Hominem
An ad hominem argument (Latin for “to the man”) attacks the person rather than his or her argument. The intention is to discredit the argument by diversion. For example a patient might say, “This doctor is rude; how he can advise me to take my medicines regularly.” Maybe true but the advice is still sound. Of course patients are more likely to follow a doctor’s advice if he is polite. This is an example of an abusive ad hominem.
Another type is the circumstantial ad hominem. An example would be if I recommend a book written by me as an excellent book for my students and somebody says, “Well you would, you get a percentage from the sales.” True, but it still may be an excellent book.
Another variation of the ad hominem is the tuquoque (Latin for “you too” and pronounced “two kwohkwey”). An example would be if a patient says, “How can this doctor advise me to lose weight. He is obese.” Yes, but then the advice is still sound. This fallacy occurs when it is assumed that an argument is wrong if the person making the claim has acted in a manner inconsistent with the claim. Still a patient is more likely to follow a doctor’s health advice if they lead by example.
Appeal to authority
(argumentum
ab auctoritate)
In this fallacy an authority is used in an argument where the authority is not really an expert on the subject matter of the argument. This type of argument is commonly used in advertising when for example a famous cricketer advocates a certain brand of milk powder. The person may know his cricket but cannot claim to be an expert in nutrition. Remember this argument is fallacious only if the authority in question is not a legitimate authority.
Appeal to ignorance
(Latin: argumentum
ad ignorantiam)
It is the proposition that something is true because it has not been proven false. For example: “You can’t prove that there aren’t Martians living under the surface of Mars, so it is reasonable for me to believe there are.” It does not however mean that one cannot have good reasons for thinking that something does not exist.
If a person were to say, “In the Bermuda Triangle many planes and ships have vanished without a trace. There must be some supernatural force acting in this region,” the person would be using ignorance as evidence for a mysterious force. Believing something does not make it so. Ignorance is just ignorance.
The appeal to ignorance fails to appreciate the fact that the limits of our understanding do not change what is true. Reality exists independently of what we believe. It is the task of science and rational thinking to discover this reality.
I wish all my readers a Happy New Year and may you all be blessed with clear thinking.