Fallacies are often categorized into different groups or families. We’ve already seen one type of categorization, between formal or structural fallacies and content fallacies.
If you search online it’s not hard to find long lists of fallacies grouped into hierarchies, like a biological classification scheme. Here’s one example. This is Gary Curtis’s website: FallacyFiles.org. It’s a great resource, tons of information on different types of fallacies.
Now if you click on the link titled “Taxonomy” then you go to a page that has over a hundred different fallacies organized into a hierarchy. I’m going to grab some images to show you parts of the hierarchy:
As you move from left to right you have general fallacy types, then sub-types of that type, that sub-sub types of that type, and so on.
So, within the category of formal fallacies there are a variety of sub-types, including fallacies of propositional logic. Within this category you can see some that you should recognize if you’ve followed the lectures on common valid and invalid argument forms. In particular we looked at affirming a disjunct, affirming the consequent and denying the antecedent.
As you can see, you could spend a lot of time just looking at formal fallacies.
Now let’s shift down a bit. This is a section of the hierarchy rooted in the category of informal fallacies:
"Informal fallacy" is another way of identifying fallacies where the problem with the argument doesn’t come down to an issue of logical form. The problem has to do with the content of what’s actually being asserted, or with other aspects of argumentation.
Notice here you can find the bandwagon fallacy that I mentioned in the previous lecture. It’s been categorized as sub-type of the category of red herrings.
Now, why am I showing you this?
It’s to make a point about the pros and cons of learning logic and argumentation by studying fallacy types.
There’s no doubt that you can learn a lot about logic and critical thinking by studying and memorizing fallacy types. And when you’re given a classification scheme like this it can help you to understand how different types of fallacies relate to one another.
There are some downsides, however.
Every fallacy is just a bad argument, and arguments are bad either because they have weak logic, or they rely on a false premise, or they violate some other basic principle of argumentation. In principle you should be able to analyze any argument in terms of a small handful of basic principles. But you can lose sight of these basic principles if you start thinking of argument analysis as essentially an exercise in pigeon-holing arguments into fallacy types.
But there are some important up-sides to studying fallacy types.
Some fallacy types are very well-known and commonly referred to by their names, like “straw man” and “red herring” and “ad hominem”. It’s important for basic critical thinking literacy to know some of these more common fallacy types.
A fallacy type is a kind of pattern. At first, learning to categorize arguments into fallacies can be hard, because you haven’t yet internalized the logical patterns, you find yourself needing to check and re-check the definitions to make sure you’ve got the right one.
But after a while you do start to internalize the patterns, and then something cool happens. You can be given an argument and you’ll be able to recognize a fallacy in it without doing a lot of conscious analysis in your head —you can just “see” it, because your brain has learned to recognize and respond to the pattern.
I think it’s harder to develop this pattern recognition skill if you’re always starting your argument analysis from first principles. So this is another reason, and I think the best reason, why studying fallacy types is important for developing critical thinking skills.
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So, we’ll be looking at few of the more common fallacy types in this tutorial course.
I’m not going to make a big deal about categorizing fallacies into a hierarchy of types. Why not? Well, first, because we’re not doing a comprehensive survey of fallacy types.
And second, because there isn’t a universal consensus on how to categorize fallacies. If you look at different online sources or at different textbooks, you’ll find a range of classification schemes. Some categories are universally used, but others aren’t, and I don’t want to waste time arguing about classification schemes.
One thing I will try to do is show how each fallacy type can be analyzed using basic principles of argument analysis, to make it clear where and how each fallacy violates the basic definition of a good argument.
I think this helps avoid the problem of focusing too much on definitions of fallacies and losing touch with the basic logical principles that underly them.
Once you see this, you see that identifying fallacies by name isn’t really what’s important. What’s important is being able to recognize a bad argument and understand why it’s bad.