Did you figure out how I was able to convince you that two dollars were missing? The trick is something you learn about in your very first algebra class. It has the boring name “order of operations.” Here is a page that explains it much better than I can – I am not a math teacher. https://www.vedantu.com/maths/order-of-operations
High school algebra teachers immediately know what I’ve done wrong. Still, often people who use mathematics every day, like engineers and physicists, are stumped. They know the rules of order of operations, but the little word puzzle seems far removed from algebra.
I once saw a used car ad with a similar trick to convince people they would save money on their used car purchase. People who want your money or to convince you of something use tricks like this, and they are damn hard to figure out.
I taught a college writing course designed to teach students how to write college papers. Part of it was how to do research. Part of it was how to detect fallacies in something you find in your research. A definition of fallacies is “incorrectness in reasoning.” You may have heard the term “peer-reviewed journal.” A person will submit a paper for publication, and it will go out to other experts in that field for checking. This is to prevent incorrect reasoning from creeping into a published article.
However, not everything in a peer-reviewed journal can be believed. Dr. Andrew Wakefield, who practiced in Great Britain, wrote a letter to a peer-reviewed journal, and they published it. Back in 1998, Dr. Wakefield took blood samples from children at his own child’s birthday party and paid them five British pounds for their trouble. Dr. Wakefield came up with the conclusion that the measles-mumps-rubella, MMR vaccine could cause autism. Dr. Wakefield lost his medical license because that letter caused many parents in Britain and United States to avoid vaccines in general. This is a case where incorrect reasoning led to health problems.
Even after looking at this case, some students still didn’t believe that the MMR vaccine wasn’t dangerous. I would ask the class if anyone would like to take up a little bet with me. I would prove to them that the color of their shirt or blouse they were wearing was precisely the opposite color; i.e., red would be green. One student would volunteer. I would tell them that I would lead them through a series of statements and asked if each one was correct. The last statement would be – thus, your red shirt is logically green. I would offer the student an A in the course if they could tell me how I did it. This little exercise clearly frustrated the students.
This would let me start to explain logical fallacies. The study of logical fallacies goes back at least to the time of Plato, three centuries before Christ. I would give each member of the class a list of logical fallacies and an exclamation for each. I would then go back to the argument about the color change in someone’s shirt or blouse and would not take them long to find out what I had done wrong. Be suspicious of everything you read. It is probably best to believe only half of what you see.
Remember, there are people out there who want to take your money. Worse yet, there are people out there trying to tell you that the sky is bright red.
