Hello and welcome to unit four of our course. In the last two units we've been focused on rules for good arguments, specifically in unit two we were focussed on rules. By means of which to evaluate and explain the validity of deductive arguments. And in unit three we were focused on rules by means of which to evaluate and explain the strength of inductive arguments. Now in unit four, we're not going to focus on good arguments. We're going to focus on bad arguments. Specifically we're going to focus on a kind of bad argument that's called a Fallacy. So what's a fallacy? Well, a fallacy is a kind of bad argument as I said, but not all bad arguments are fallacies. Some arguments are bad because their premises are false. But that's not why fallacies are bad. Of course, a fallacy could have false premises also. But that's not what makes an argument a fallacy. What makes an argument a fallacy is that its premises, whether they are true or false, don't support its conclusion. They're not the right kind of premises to support the conclusion that the argument draws. Whether they're true or false, so that's what makes a fallacy. Let me give you some examples. I'll show you what I have in mind. So consider this argument. The majority of violent crime in the United States is committed by men who earn less than $30,000 per year. By the way, that's true. Conclusion that the argument draws from that. Therefore when you see a man who earns less than $30,000 a year, he is likely to be a violent criminal, okay. Now that's a bad argument. But it's not a bad argument because its premise is false. But, actually its premise is true. So what makes it a bad argument? What makes it a bad argument, is that its premise doesn't support its conclusion. Right, the premise says that, most of the things that fall into, one category The category of perpetrators of violent crime in the United States also fall into a second category, the category of men who earn less than $30,000 a year. But then the conclusion says that most of the things that fall into that second category, the category of men who earn less than tha, $30,000 a year, also fall into that first category. The category of perpetrators of violent crime. And that conclusion isn't supported by the premise. Just because the majority of things in one category also fall into a second category. It doesn't mean that the majority of things in that second category also fall into that first category. So, that argument is a fallacy. And it's a fallacy. It's a bad argument, even though its premise is true. So that's one example of a fallacy. Here's another example of a fallacy. Consider this argument, premise one. If the national government increased the spending, investors will lose confidence in the national currency. Comes to, investors have lost confidence in the national currency. Conclusion, the national government must have increased spending. Okay, now, since the premises don't specify which nation we're talking about, we could imagine that there's some nation of which both of the premises are true. Right? We don't need to get into the details of which nation that would be, but imagine that there's some nation of which both of the premises are true. But even if both of the premises are true, concerning that nation, they don't support the conclusion. So this argument is a fallacy. It's a bad argument. Not because the premises are false. But because, even if the premises are true. They still don't support the conclusion. Right, the premises say, if one thing is true. Let's say if national government increases spending. Then a second thing is also going to be true. Investors will lose confidence. Then the second premise says that second thing is true. Investors have lost confidence, but the conclusion says so the first thing must be true, but that doesn't follow, right? Remember how conditionals work. Just because a conditional is true and it's consequence is true. It doesn't follow from that the antecedent of the conditional is true. You can see that from the, looking at the truth table for the conditional. So, this is an example of an argument. In which the premises don't support the conclusion. Even if the premises are true. So this argument is also a fallacy. Now, here's an example of a bad argument that's not a fallacy. Look at this one. most of the crude oil in the world is in Texas. So, that's premise one. Premise two, Texas is going to secede from the United States. So conclusion, domestic oil availability in the United States is going to plummet. Okay now this argument, although it's a bad argument, it's not a fallacy. It's not a fallacy because the premises really do support the conclusion. If both of those premises are true, then the conclusion has got to be true, right. If most of the crude oil in the world is in Texas, and Texas is going to secede from the United States, then domestic oil availability in the United States really is going to plummet. Thankfully for domestic oil availablity in the United States though. Those two premises are not true. In fact, neither of them is true. So in any case, I'm quite confident that neither of them is true. So this is a bad argument, not because the premises don't support the conclusion. They do support the conclusion. This is a bad argument because the premises aren't true. Okay, so I've given you examples of bad arguments that are fallacies and a bad argument that's not a fallacy. But, for a complete list of fallacies, anyhow a, a nearly complete list of fantasies, I recommend the URL. This URL is the entry on Wikipedia for a list of fallacies and it's a very long and nearly complete list of fallacies. So, you can look at that list, think about the different kinds of fallacies there are and we are going to describe them in more detail in this unit of the course. In this week in particular, in week nineof the course, we're going to focus on fallacies. That result from the misuse of expressions that are vague or ambiguous, okay. See you next time.
