02a. How to Argue - Philosophical Reasoning. Part 1/2.

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Hank Green: Aristotle once described humans as “the rational animal.” Well, actually, he said that “man is the rational animal,” but we don't have to be sexist just because he was.

And if you've ever gotten into an argument with someone about religion or politics or which Hemsworth is the hottest, then you've experienced how irrational people can be about their opinions.

But what Aristotle meant is that rationality is our distinguishing characteristic – it's what sets us apart from the beasts. And no matter how much you disagree with someone about God or Obama or Chris Hemsworth, you can at least grant that they are not beasts.

Because, most of the time at least, people can be persuaded. By arguments. You use arguments all the time -- in the comments, at family dinners, with your friends – you probably just don't think of them the same way that philosophers do.

When you try and convince your parents to loan you the car, or when you're talking up Crash Course to your friends, you are using arguments. Thanks, by the way.

Each time you tell someone to do or believe something -- or when you're explaining why you do or believe something -- you are giving an argument. The problem is, the vast majority of people aren't really good at arguments. We tend to confuse making a good argument with, like, having witty comebacks, or just making your points more loudly and angrily, instead of building a case on a solid foundation of logic. Which can be harder than it sounds.

But learning about arguments and strong reasoning will not only make you a better philosopher, it will also set you up to be a more persuasive person. Someone who people will listen to. Someone who's convincing. So, yeah, these skills are beneficial no matter what you want to do with your life. So you might as well know how to argue properly.

[Theme Music]

If you want to learn how to argue, then you should probably start about 2400 years ago, when Plato was laying out how reason can, and should, function in the human mind. He believed that we all have what he called a tripartite soul – what you might think of as your “self,” or your psyche, divided into three parts.

First, there's the rational, or logical part of the soul, which represents cool reason. This is the aspect of your self that seeks the truth and is swayed by facts and arguments. When you decide to stop eating bacon for two meals a day because, as delicious as it is, it's bad for you, then you make that decision with the guidance of the rational part of your soul. But then there's the spirited aspect, often described as the emotional part of the self, although that doesn't really quite capture it.

The spirited soul isn't just about feeling -- it's also about how your feelings fuel your actions. It's the part that responds in righteous anger at injustice, the part that drives your ambition, and calls upon you to protect others. It gives you a sense of honor and duty, and is swayed by sympathy.

So if you decide to stop eating bacon because you just finished reading Charlotte's Web, and now you're in love with Wilbur, then you're being guided by the spirited part of your soul. But we share the next part of our soul with other animals, be they pig, or moose, or aardvark.

The appetitive part is what drives you to eat, have sex, and protect yourself from danger. It is swayed by temptations that are carnal, and visceral. So at those times when you go ahead and just EAT ALL THE BACON because it just smells so dang good, the appetitive aspect of your soul is in control.

Now, Plato believed that the best human beings -- and I should point out here that Plato most definitely did believe that some people were better than others -- are always ruled by the rational part of their soul, because it works to keep the spirited and the appetitive parts in check.

People who allow themselves to be ruled by their spirited or appetitive selves are base, he believed, and not fully, properly human. Now, most of us don't buy into the concept of the tripartite soul anymore -- or the idea that some humans are less human than others. But we do understand that we're all motivated by physical desires, emotional impulses, and rational arguments. And philosophers continue to agree with Plato that reason should be in the driver's seat.

So, how do you know if you're good at it? How can you test your reasoning?

Well, let's head over to the Thought Bubble for some Flash Philosophy. Throughout this course, we're going to apply our philosophical skills by pondering puzzles, paradoxes, and thought experiments. Because remember: Philosophers love thinking about questions -- especially ones that don't have ready answers.

So think of these exercises as philosophical wind-sprints -- quick tests of your mental abilities.

And here's a doozy, from 20th century British thinker Bertrand Russell, one of the pioneers of what's known as analytic philosophy. Say there's a town in which all men are required by law to be clean-shaven. This town has only one barber, a man, who must follow strict rules:

● Rule number one: He must shave all men who do not shave themselves.

● Rule number two: He must not shave any man who does shave himself.

It's the nightmare of every libertarian and every mustachio'd hipster. But here's the question: Does the barber shave himself? Cause think about it: The barber only shaves men who don't shave themselves. So if he does shave himself, then he must not, because the barber's not allowed to shave guys who shave themselves.

But, if he doesn't shave himself, then he has to be shaved by the barber, because that's the law.

Russell came up with this puzzle to illustrate the fact that a group must always be a member of itself.

That means, in this case, that “all men who shave themselves” has to include every guy who shaves himself, including the barber. Otherwise, the logic that dictates the group's existence just doesn't hold up. And if the barber is a logical impossibility, then he can't exist, which means the reasoning behind his existence is inherently flawed. And philosophy doesn't tolerate flawed reasoning.

So, how do we make sure that we're ruled by good, sound, not-flawed reason?

By perfecting the art of the argument. An argument, in philosophy, isn't just a shouting match. Instead, philosophers maintain that your beliefs should always be backed up by reasons, which we call premises.

Premises form the structure of your argument. They offer evidence for your belief, and you can have as many premises as you like, as long as they support your conclusion, which is the thing that you actually believe.

So, let's dissect the anatomy of an argument. There are actually several different species of arguments. Probably the most familiar, and the easiest to carry out, is the deductive argument. The main rule of a deductive arguments is: if your premises are true, then your conclusion must be true. And knowing that something is actually true is very rare, and awesome.