Michael LaBossiere - 76 Fallacies

In addition to combining the content of 42 Fallacies and 30 More Fallacies , this book features some revisions as well as a new section on common formal fallacies.

As the title indicates, this book presents seventy six fallacies. The focus is on providing the reader with definitions and examples of these common fallacies rather than being a handbook on winning arguments or general logic.

Understanding what a fallacy is requires that you first have at least a basic understanding of arguments in the philosophical sense. In philosophy, an argument is not a fight or even a dispute. Rather, an argument is as set of claims (statements that can be true or false) that are related in a way that one of them is supported by the others. Another way to look at it is that one claim is presented to be proven and the other claims are presented as evidence or reasons for that claim,

In technical terms, the claim being argued for is known as the conclusion. A single argument has one (and only one) conclusion. One way to spot a conclusion is to ask what is the point that is supposed to be proven here? If there is no point, then there is no argument. Of course, a person can make a point without offering proof, so what is also needed is evidence or reasons. The evidence or reasons being presented in support of the conclusion are known as premises. An argument will always have at least one premise, but there is no limit on the number allowed. One way to find premises is to ask what reasons, if any, are being given in support of the conclusion? If no reasons are given, then there is no argument present.

In general, philosophers take arguments to be of two main types: deductive and inductive. A deductive argument is an argument such that the premises provide (or are supposed to provide) complete support for the conclusion. An inductive argument is an argument such that the premises provide (or are supposed to provide) some degree of support (but less than complete support) for the conclusion. The support given by the premises to the conclusion is a matter of logic and, interestingly enough, has nothing to do with whether the premises are actually true or not. I will say more about this later.

If a deductive arguments premises properly support the conclusion, the argument is valid. In technical terms, a valid deductive argument is such that if all its premises were true, then its conclusion must be true.

If a deductive argument is valid and actually does have all true premises, then it is sound. An argument can be valid and unsound by having one or more false premises.

If a deductive argument is such that the premises could all be true while the conclusion is false at the same time, then the argument is invalid. Invalid arguments are always unsound. This is because a sound argument must be valid and have all true premises.

An invalid argument is also known as a formal fallacy or a deductive fallacy. This book includes some of the classic named deductive fallacies.

Deductive arguments are tested for validity using a variety of methods, such as Venn diagrams, truth tables and logical proofs. While these are interesting (well, to some people), they will not be covered in this book.

Inductive arguments are assessed differently from deductive arguments. If the premises of an inductive argument support the conclusion adequately (or better) it is a strong argument. It is such that if the premises are true, the conclusion is likely to be true. If a strong inductive argument has all true premises, it is sometimes referred to as being cogent.

One feature of inductive logic is that even a strong inductive argument can have a false conclusion even when all the premises are true. This is because of what is known as the inductive leap: with an inductive argument the conclusion always goes beyond the premises. However, this does not make all inductive reasoning fallacious (although it does make it all technically invalid). An inductive fallacy occurs when an arguments premises do not adequately support the conclusion. In most fallacies this occurs because the premises being offered have little or no logical connection to conclusion. The fallacies covered in this book are of the informal inductive sort.

Before moving on to the actual fallacies, it is necessary to have a short discussion about what fallacies are not. Unfortunately for those who teach about fallacies, people often use the term fallacy when they are actually referring to a factual error. For example, someone might say a lot of people think that Google created Android from scratch, but that is a fallacy. Google actually based Android on Linux. While thinking that Android was created from scratch would be an error, it is an error about the facts, rather than an error in logic. If someone said Android is awful. After all, a fair number of creepy geeks use it, then this would be an error in logic. Even if creepy geeks use Android, this does not prove that the operating system is awful. While both of these are mistakes, they are two different types of mistakes.

To see why, think about balancing a checkbook. I can make a mistake by doing the math incorrectly (which would be an error in reasoning) and I can make a mistake by entering the wrong amount for a check. These errors are different and treating them the same would cause confusion. The same applies for fallacies and factual errors.

To use another analogy, think about cooking. One way I could screw up a meal is by cooking badly. This would be like an error in logic. Another way is that I could use the wrong (or bad) ingredients. That would be like making a factual error.

As such, it is one thing to get the facts wrong (factual error) and quite another to reason badly about them (fallacy).

So, a fallacy is an error in reasoning/logic. To be more specific, a fallacy is an argument in which the premises fail to provide adequate logical support for the conclusion. A deductive fallacy, as noted above, is a deductive argument that is invalid (it is such that it could have all true premises and still have a false conclusion). Whether an argument is valid or invalid is an objective matter and can be tested by various means, such as truth tables and proofs.

An inductive fallacy is less formal than a deductive fallacy. They are weak inductive arguments in which the premises do not provided enough support for the conclusion. While deductive arguments can be tested with objective and definitive means, the same is not true for inductive arguments. There are objective standards, but assessing informal fallacies is somewhat like judging figure skating: really good and really bad cases are easy to spot, but there are situations where there will be reasonable dispute.