By Andrew Dart, author of 'Building Your Skeptical Toolkit'.
A logical fallacy is an error or flaw in a logical argument that causes the logic to become invalid. The best way to understand this is to look at them in light of how logical arguments should work. All arguments or debates contain the same basic structure: A therefore B. The person arguing starts by putting forward a premise or two (A), which is usually the fact or assumption upon which their argument is based. They then use a logical principle (therefore) to get to their conclusion (B). A good example of this is a logical principle known as equivalence. Here you would start with the premise that A=B and B=C. From this you can apply the logical principle of equivalence to arrive at the conclusion that therefore A=C. This is a logical argument. A logical fallacy on the other hand is a false or incorrect logical principle and as such any argument based upon a logical fallacy is not valid.
It is important to note that just because a conclusion is reached via a logical fallacy it doesn’t necessarily mean that the conclusion itself is wrong; just that the specific argument used to get there is a bad one. In fact, there is a logical fallacy, the fallacy fallacy, which actually deals with the idea that just because the argument contains a fallacy the conclusion must therefore be wrong. This is not always the case. Saying that England is a country because grass is green is a fallacious and illogical argument; however, the conclusion that England is a country is still correct. Ok, so let’s take a look at some of the more common logical fallacies you should keep an eye out for:
If you notice anything that could be changed, improved or updated? Or do you know of a logical fallacy missing from this list? Let us know you by emailling us at firstname.lastname@example.org
Test Your Skills
Being able to spot logical fallacies is a good skill to have as a skeptic. It can help you identify flaws in arguments about topics with which you are not that familiar, and it can also help you to correct mistakes in your own reasoning and assist you in seeing where you may be accepting things for bad reasons. There are many more logical fallacies out there and during your skeptical life you will encounter far more of them than you could ever wish for, you have been warned. So, as we did with syllogistic reasoning let’s put these new skills to the test, shall we? I’ll end this article with a few statements and all you need to do is identify the logical fallacy in each one. Good luck.
Barry: I don’t see why my tax payer money should go towards funding religious based schools.
Steve: So, you don’t want to see children get a good education then?
“If we make gay marriage legal then it won’t be long until people want to marry children and animals.”
“Well I’ve never seen a boat or fish produce a wake like that in the water, so it must have been something else.”
“We need to have the death penalty in order to discourage violent crime.”
“I don’t know why you bother having a diet coke with your Big Mac; it is hardly going to make you a super model.”