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Logical Fallacies

Logical Fallacies

Author: Gavin McCall

This lesson teaches the most common logical fallacies.

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Welcome back to English Composition. My name is Gavin McCall. Thanks for joining me.

What are we going to learn today? We're going to learn about logical fallacies, what they are and why it's important for us to study them. Then we'll take the time to go over a few of the most common fallacies, so you'll be better able to see them coming as you read and write.

The first question we need to ask is, what is a logical fallacy? It's an instance of flawed reasoning that often sounds plausible, even though it's based on faulty logic.

And don't worry if that doesn't explain it enough. We'll go over a bunch of the most common fallacies. So by the end of this video, you'll have a strong grasp on what a logical fallacy is.

First, though, we need to answer the question, why do we need to study logical fallacies? What's the big deal? Well, the danger of logical fallacies isn't just that they employ faulty reasoning or false causality. It's that they do so while seeming not to.

Fallacies are tricky, because they're easy to miss, which is why readers need to be careful. Less than honest writers can use them to make the argument seem more reasonable than they are, to make their position seem stronger, and ultimately to trick readers like you into agreeing with them, rather than earning your trust.

But don't get me wrong. Not everyone who commits a logical fallacy, even in writing, is doing so maliciously. The flip side of fallacies often seeming reasonable on the surface is that it's relatively easy for a careless or unobservant writer to use a fallacy in a text. This is why the same kind of critical thinking that we use in engaged reading is also necessary during the writing process.

For most of the rest of this video, we'll be discussing some of the trickiest, most commonly committed fallacies. But believe me, it won't be in an exhaustive list. There are always more.

The first logical fallacy we're going to look at is called the bandwagon fallacy, or argumentum ad populum. This fallacy claims an argument is valid because many people believe it is. Here's an example.

Note how it doesn't take into account biases. And, like pretty much any other example of this fallacy, it assumes people's beliefs and opinions are always correct. Sometimes they are. But keep in mind, before Galileo, people believed the sun revolved around the Earth.

The second is hasty generalization, sometimes called loose generalization. This is when a writer uses too small of a sample to draw generalizations about entire groups. Here's a pretty silly example I came up with.

But keep in mind that this fallacy is at the heart of much of the prejudice and stereotyping people suffer from every day. Any time somebody with little to no experience with or knowledge about a group people draws a loose or hasty generalization about every member of that group, well, that's this.

Next, let's look at the straw man fallacy. This is very common in politics and journalism in that it happens when someone misrepresents or oversimplifies an opposing argument, creating a false representation, or straw man, which is easier to knock down. Then he or she can pretend to have won the debate.

Here's an example. I made up the exact wording here, but it probably wouldn't be too hard for you to find a real world replica. And before I offend anyone's political sensibilities, here's one from or to the other side.

The point here should be clear enough. It's easy to set up and knock down the straw man. Refuting an actual argument takes work, but it's worth it, because it's real.

The slippery slope fallacy is another favorite of those in politics and journalism. This fallacy predicts a chain of events that will lead to either a terrible or a great situation, if one event is made or allowed to occur. This fallacy relies on unsupported, emotional appeals, usually fear, rather than trying to prove one event will necessarily lead to another.

Here's one example. It implies that everyone who tries any drug will necessarily ruin his or her life. Of course, this does happen sometimes. But that's the point. In order for this fallacy to fool anyone, it has to be realistic enough to allow the emotional reaction to bridge the gap between the two events for us, if only in the reader's mind.

The next fallacy we'll look at is called either circular reasoning are begging the question. This happens when an argument bases its inclusion on its conclusion, usually by rephrasing it. One of the first examples I could think of is the statement that one should believe in God because the Bible says God exists. And we should believe in the Bible because it's the word of God.

It's similar to saying that you should believe me, because I'm honest. Nothing can be proven by stating it twice. And besides, if you're trying to prove issues of faith, you've missed the point, circular reasoning or no.

Ad hominem is Latin for to the person. This fallacy is committed when, instead of focusing on the argument, issue, or evidence, an opponent instead attacks the character or background of the speaker or writer.

Here are a couple examples. It should seem pretty clear that there's a difference between refuting the credibility of a source of information and trying to imply that, because of inequality of the speaker or writer possesses, his or her argument is somehow invalid.

Post hoc, ergo propter hoc is definitely my favorite fallacy to say out loud. It's Latin for after this, therefore because of this. This is the logic behind this kind of fallacy-- assuming causality because of chronology. Hence, because x happened before y, x caused y.

For example, arguing that a social policy change is responsible for the crime rate dropping. This is a pretty silly example, as you can see. But you might be surprised how often politicians try this kind of thing, especially in election years.

The last type of logical fallacy we'll focus on today is the false dilemma, or false dichotomy. It's also referred to as either/or or black and white reasoning. It's another fallacy that's often found in the realm of politics and journalism.

This fallacy happens when a writer or speaker falsely limits the number of possible positions that can be taken on a particular issue. It's a refusal or a failure to acknowledge the complexity of the subject at hand. Here's an example.

As you can see, it falsely assumes that one must support the war in order to support the troops. Essentially, this and other examples of the false dilemma fallacy boil down to a you're either with me or you're against me mentality with no room for any of the troubling, beautiful complexity of the real world.

Before I move on, let's talk briefly about all of the fallacies we've covered so far. So all of these types-- the bandwagon, the loose or hasty generalization, the straw man fallacy, and the slippery slope, as well as circular reasoning, ad hominem, post hoc, ergo propter hoc, and the false dilemma-- why is it important to remember and understand them all?

Well, for one, you're likely to encounter them in readings or assignments. But more importantly, being aware of these fallacies and how they work will make you a more informed reader, which will make it harder for you to be fooled by any of these or other fallacies. An awareness of logical fallacies will help you become not only a better reader but it will help you think and write more critically.

What did we learn today? We learned a lot, actually, all about logical fallacies, from what they are and why they're important. Then we covered eight of the trickiest fallacies out there. I'm Gavin McCall. Thanks for joining me.

Terms to Know
Logical Fallacies

Instances of flawed logic or reasoning in writing that often sound plausible despite their faulty base.