How to Argue - Philosophical Reasoning: Crash Course Philosophy #2

CrashCourse
16 Feb 201609:43
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TLDRIn this Crash Course Philosophy episode, the importance of rationality as a defining human trait is explored, contrasting it with irrational behaviors. The script delves into the art of argumentation, highlighting the difference between everyday persuasion and philosophical reasoning. It introduces Plato's tripartite soul concept and the significance of reason over emotion and desire. Furthermore, it explains deductive arguments, emphasizing the necessity of sound premises for valid reasoning, using the barber paradox to illustrate logical consistency. The episode encourages mastering argumentation to enhance persuasive abilities and critical thinking.

Takeaways
  • πŸ“š Aristotle described humans as 'the rational animal', emphasizing rationality as a distinguishing human characteristic.
  • πŸ—£οΈ People often engage in arguments in daily life, but may not approach them with the same rigor as philosophers.
  • 🧠 Plato's concept of a tripartite soul includes the rational, spirited, and appetitive parts, suggesting that the rational part should ideally govern the others.
  • πŸ– The appetitive part of the soul is shared with animals and drives basic desires like eating and self-preservation.
  • πŸ€” Philosophers believe that reason should guide human actions, and that good reasoning can be tested through thought experiments and puzzles.
  • πŸ’‘ Bertrand Russell's barber paradox illustrates the logical inconsistencies that can arise when a group's definition does not include itself.
  • πŸ” Deductive arguments are a type of reasoning where the truth of the premises guarantees the truth of the conclusion.
  • πŸ”— In deductive reasoning, the relationship between premises and conclusion is called entailment, where the conclusion logically follows from the premises.
  • ❌ Invalid arguments may have true premises and conclusions but fail to establish a logical connection between them.
  • πŸ” Validity in arguments refers to the logical structure where if the premises are true, the conclusion cannot be false, but this does not guarantee the truth of the premises themselves.
  • πŸ“ˆ The goal in philosophical reasoning is to achieve sound arguments, where the premises are true and the argument is valid, ensuring the conclusion is necessarily true.
Q & A
  • What did Aristotle describe humans as?

    -Aristotle described humans as 'the rational animal,' emphasizing that rationality is the distinguishing characteristic that sets humans apart from other animals.

  • Why is rationality considered important in arguments?

    -Rationality is important in arguments because it allows people to be persuaded by logical reasoning rather than just emotional reactions or loud assertions, making the arguments more convincing and persuasive.

  • What is the tripartite soul according to Plato?

    -The tripartite soul, as described by Plato, consists of three parts: the rational or logical part, the spirited part, and the appetitive part. The rational part seeks truth and is swayed by facts and arguments, the spirited part is about emotions and actions, and the appetitive part drives physical desires and self-preservation.

  • How does Plato view the best human beings?

    -Plato believed that the best human beings are those who are ruled by the rational part of their soul, as it keeps the spirited and appetitive parts in check, leading to a more balanced and virtuous life.

  • What is the barber paradox presented by Bertrand Russell?

    -The barber paradox is a thought experiment where a town has a barber who shaves all men who do not shave themselves and does not shave those who do. The paradox arises when considering whether the barber shaves himself, leading to a logical inconsistency.

  • What is the purpose of the barber paradox in the script?

    -The barber paradox is used to illustrate the importance of logical consistency in arguments and to show that a group must always be a member of itself, highlighting the necessity for sound reasoning in philosophy.

  • What is an argument in philosophical terms?

    -In philosophical terms, an argument is a set of statements, called premises, that provide evidence for a belief, leading to a conclusion. It is not merely a verbal dispute but a structured reasoning process.

  • What is a deductive argument?

    -A deductive argument is a type of reasoning where if the premises are true, the conclusion must also be true. It is a form of logical reasoning that moves from general premises to a specific conclusion.

  • What is the difference between validity and soundness in arguments?

    -Validity in an argument means that if the premises are true, the conclusion cannot be false. Soundness, on the other hand, refers to an argument that is not only valid but also has all true premises, ensuring the conclusion is guaranteed to be true.

  • Why are deductive arguments valued in philosophy?

    -Deductive arguments are valued in philosophy because they can provide certainty. If the premises are true and the argument is valid, the conclusion must also be true, offering a reliable method for establishing truths.

  • What is the role of premises in an argument?

    -Premises in an argument serve as the foundation that supports the conclusion. They provide the evidence or reasons that justify the belief expressed in the conclusion, forming the structure of the argument.

Outlines
00:00
πŸ€“ The Importance of Rationality and Arguments

This paragraph introduces the concept of rationality as a defining human characteristic, contrasting it with the irrationality often displayed in debates about religion, politics, or personal preferences. It emphasizes the importance of using logical arguments to persuade others, rather than relying on emotional outbursts or witty comebacks. The narrator suggests that understanding and mastering the art of argumentation can make one more persuasive and influential, which is beneficial in various aspects of life. The historical context is provided by mentioning Plato and his views on reason, setting the stage for a deeper exploration of philosophical reasoning.

05:01
πŸ“š Deductive Arguments and Their Structure

This paragraph delves into the structure and principles of deductive arguments, a fundamental aspect of philosophical reasoning. It explains that deductive arguments are built on premises that, if true, necessarily lead to a true conclusion. The narrator uses the example of human mortality to illustrate how deductive reasoning works, showing how specific conclusions can be logically derived from general premises. The paragraph also discusses the difference between a valid argument (where the premises entail the conclusion) and a sound argument (where the premises are true and the argument is valid). It highlights the importance of having true premises to ensure the soundness of an argument, and the limitations of deductive reasoning due to the rarity of having indisputably true premises.

Mindmap
Upcoming Topics
Philosophical Inquiry
Deducing from Known Premises
Soundness and Truth
Invalid Argument
Valid Deductive Argument
Validity and Soundness
Deductive Arguments
Premises and Conclusions
Flawed Reasoning
Logical Implications
Bertrand Russell's Barber Paradox
Modern Perspective
Rationality's Role
Plato's Tripartite Soul
Building Logical Foundations
Misunderstandings in Argumentation
Use of Arguments
Importance of Rationality
Irrationality in Arguments
Aristotle's Definition
Further Exploration
Examples and Counterexamples
The Art of Argument
Philosophical Puzzles
Philosophical Foundations
Arguments in Daily Life
Introduction to Rationality
Crash Course Philosophy
Alert
Keywords
πŸ’‘Rationality
Rationality refers to the ability to think and act in accordance with reason and logic. In the video, it is presented as a defining human characteristic that distinguishes us from animals, as Aristotle suggested. The script uses rationality to discuss the importance of logical argumentation in persuading others, contrasting it with emotional or instinctual reactions.
πŸ’‘Argument
In the context of the video, an argument is a set of statements or reasons intended to persuade others to accept a particular point of view or to act in a certain way. The script emphasizes that while people often use arguments in everyday life, philosophers approach them with a focus on logical structure and sound reasoning, rather than emotional appeals or loudness.
πŸ’‘Deductive Argument
A deductive argument is a type of logical reasoning where the conclusion is necessarily true if the premises are true. The video script provides an example of a deductive argument with premises about human mortality and Socrates being human, leading to the conclusion that Socrates is mortal. It is a key concept in the video's discussion of logical reasoning and the pursuit of certainty in arguments.
πŸ’‘Premise
A premise is a statement or proposition that forms the basis for an argument or inference. The script explains that in a philosophical argument, premises are the evidence supporting the conclusion. They are crucial for building a valid deductive argument, as they must all be true for the argument to be sound.
πŸ’‘Conclusion
The conclusion is the final statement or judgment that is derived from the premises of an argument. In the video, the conclusion is what the arguer believes based on the premises provided. It is highlighted that in a deductive argument, if the premises are true, the conclusion must also be true, which is a key aspect of logical reasoning.
πŸ’‘Entailment
Entailment in logic refers to the relationship between statements where the truth of one requires the truth of another. The script uses the term to describe how the premises in a deductive argument lead to the conclusion, such as knowing that all humans are mortal and that Socrates is human entails that Socrates is mortal.
πŸ’‘Validity
Validity in the context of arguments refers to the logical structure where if the premises are true, the conclusion cannot be false. The video script explains that an argument is valid if the reasoning is sound and the conclusion follows logically from the premises, regardless of whether the premises are actually true.
πŸ’‘Soundness
Soundness in logic is the property of an argument being both valid and having all true premises, ensuring that the conclusion is necessarily true. The script emphasizes the importance of sound arguments in philosophy, as they represent the ideal of logical reasoning without flaws.
πŸ’‘Tripartite Soul
The tripartite soul is a concept by Plato, dividing the human soul into three parts: the rational, spirited, and appetitive. The video script uses this concept to illustrate the different aspects of human motivation and how they relate to reason, emotion, and physical desires, respectively.
πŸ’‘Barber Paradox
The Barber Paradox, introduced by Bertrand Russell, is a logical puzzle presented in the video to illustrate the concept of self-reference and the potential for logical inconsistencies. The script uses the paradox to discuss the necessity of a group including itself and the implications for logical reasoning.
πŸ’‘Persuasion
Persuasion in the video is the act of convincing others to adopt a belief or take a particular action through the use of arguments. The script suggests that learning about arguments and reasoning can make one a more persuasive person, which is beneficial in various aspects of life beyond philosophy.
Highlights

Aristotle described humans as 'the rational animal', emphasizing rationality as a distinguishing characteristic.

Rationality is what sets humans apart from beasts, as people can generally be persuaded by arguments.

Arguments are used in everyday life, such as convincing parents or friends, but most people are not adept at constructing solid arguments.

Learning about arguments and strong reasoning can make one a better philosopher and a more persuasive person.

Plato's concept of a tripartite soul includes the rational, spirited, and appetitive parts, with the rational part being the most important.

The rational part of the soul seeks truth and is swayed by facts and arguments, while the spirited part is driven by emotions and actions.

The appetitive part of the soul is shared with animals and is driven by basic desires and protections.

Plato believed that the best human beings are ruled by the rational part of their soul, keeping the spirited and appetitive parts in check.

Modern philosophers agree with Plato that reason should be the guiding force in human behavior.

Bertrand Russell's barber paradox illustrates the logical inconsistency in a group that must include itself.

A deductive argument is one where if the premises are true, the conclusion must also be true.

Deductive reasoning begins with general facts and reasons down to specific conclusions.

An argument is valid if the truth of the premises guarantees the truth of the conclusion.

Validity does not guarantee the truth of the premises or the conclusion, only that if the premises are true, the conclusion cannot be false.

A deductively sound argument is one that is both valid and has all true premises, ensuring the conclusion is true.

Deductive arguments provide certainty but are limited by the need for known true premises.

The value of reason, the structure of arguments, and deductive reasoning were discussed in this episode.

Transcripts
00:03

Crash Course Philosophy is brought to you by Squarespace.

00:06

Squarespace: share your passion with the world.

00:08

Aristotle once described humans as β€œthe rational animal.”

00:12

Well, actually, he said that β€œman is the rational animal,” but we don’t have to

00:16

be sexist just because he was.

00:17

And if you’ve ever gotten into an argument with someone about religion or politics or which

00:21

Hemsworth is the hottest, then you’ve experienced how irrational people can be about their opinions.

00:26

But what Aristotle meant is that rationality is our distinguishing characteristic – it’s

00:30

what sets us apart from the beasts.

00:32

And no matter how much you disagree with someone about God or Obama or Chris Hemsworth, you

00:36

can at least grant that they are not beasts.

00:39

Because, most of the time at least, people can be persuaded. By arguments.

00:43

You use arguments all the time -- in the comments, at family dinners, with your friends -- you

00:47

probably just don’t think of them the same way that philosophers do.

00:50

When you try and convince your parents to loan you the car, or when you’re talking

00:52

up Crash Course to your friends, you are using arguments. Thanks, by the way.

00:56

Each time you tell someone to do or believe something -- or when you’re explaining why

01:00

you do or believe something -- you are giving an argument.

01:03

The problem is, the vast majority of people aren’t really good at arguments.

01:06

We tend to confuse making a good argument with, like, having witty comebacks, or just

01:10

making your points more loudly and angrily, instead of building a case on a solid foundation

01:15

of logic. Which can be harder than it sounds.

01:17

But learning about arguments and strong reasoning will not only make you a better philosopher,

01:22

it will also set you up to be a more persuasive person. Someone who people will listen to.

01:26

Someone who’s convincing.

01:27

So, yeah, these skills are beneficial no matter what you want to do with your life.

01:30

So you might as well know how to argue properly.

01:33

[Theme Music]

01:43

If you want to learn how to argue, then you should probably start about 2400 years ago,

01:47

when Plato was laying out how reason can, and should, function in the human mind.

01:52

He believed that we all have what he called a tripartite soul – what you might think

01:56

of as your β€œself,” or your psyche, divided into three parts.

01:59

First, there’s the rational, or logical part of the soul, which represents cool reason.

02:03

This is the aspect of your self that seeks the truth and is swayed by facts and arguments.

02:07

When you decide to stop eating bacon for two meals a day because, as delicious as it is,

02:12

it’s bad for you, then you make that decision with the guidance of the rational part of your soul.

02:16

But then there’s the spirited aspect, often described as the emotional part of the self,

02:21

although that doesn’t really quite capture it.

02:23

The spirited soul isn’t just about feeling -- it’s also about how your feelings fuel your actions.

02:27

It’s the part that responds in righteous anger at injustice, the part that drives your

02:32

ambition, and calls upon you to protect others.

02:34

It gives you a sense of honor and duty, and is swayed by sympathy.

02:38

So if you decide to stop eating bacon because you just finished reading Charlotte’s Web,

02:42

and now you’re in love with Wilbur, then you’re being guided by the spirited part of your soul.

02:45

But we share the next part of our soul with other animals, be they pig, or moose, or aardvark.

02:50

The appetitive part is what drives you to eat, have sex, and protect yourself from danger.

02:55

It is swayed by temptations that are carnal, and visceral.

02:58

So at those times when you go ahead and just EAT ALL THE BACON because it just smells so

03:02

dang good, the appetitive aspect of your soul is in control.

03:06

Now, Plato believed that the best human beings -- and I should point out here that Plato

03:09

most definitely did believe that some people were better than others -- are always ruled

03:13

by the rational part of their soul, because it works to keep the spirited and the appetitive parts in check.

03:19

People who allow themselves to be ruled by their spirited or appetitive selves are base,

03:23

he believed, and not fully, properly human.

03:26

Now, most of us don’t buy into the concept of the tripartite soul anymore -- or the idea

03:30

that some humans are less human than others.

03:32

But we do understand that we’re all motivated by physical desires, emotional impulses, and rational arguments.

03:37

And philosophers continue to agree with Plato that reason should be in the driver’s seat.

03:42

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

03:45

Well, let’s head over to the Thought Bubble for some Flash Philosophy.

03:48

Throughout this course, we’re going to apply our philosophical skills by pondering puzzles, paradoxes, and thought experiments.

03:54

Because remember: Philosophers love thinking about questions -- especially ones that don’t have ready answers.

03:59

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

04:04

And here’s a doozy, from 20th century British thinker Bertrand Russell, one of the pioneers

04:08

of what’s known as analytic philosophy.

04:10

Say there’s a town in which all men are required by law to be clean-shaven. This town

04:14

has only one barber, a man, who must follow strict rules:

04:18

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

04:22

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

04:25

It’s the nightmare of every libertarian and every mustachio’d hipster. But here’s the question:

04:30

Does the barber shave himself?

04:32

Cause think about it: The barber only shaves men who don’t shave themselves. So if he does

04:37

shave himself, then he must not, because the barber’s not allowed to shave guys who shave themselves.

04:41

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

04:46

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

04:51

That means, in this case, that β€œall men who shave themselves” has to include every

04:55

guy who shaves himself, including the barber.

04:57

Otherwise, the logic that dictates the group’s existence just doesn’t hold up.

05:01

And if the barber is a logical impossibility, then he can’t exist, which means the reasoning

05:06

behind his existence is inherently flawed.

05:08

And philosophy doesn’t tolerate flawed reasoning.

05:10

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

05:15

By perfecting the art of the argument.

05:17

An argument, in philosophy, isn’t just a shouting match.

05:20

Instead, philosophers maintain that your beliefs should always be backed up by reasons,

05:24

which we call premises.

05:26

Premises form the structure of your argument. They offer evidence for your belief, and you

05:30

can have as many premises as you like, as long as they support your conclusion, which

05:34

is the thing that you actually believe.

05:35

So, let’s dissect the anatomy of an argument.

05:37

There are actually several different species of arguments. Probably the most familiar,

05:41

and the easiest to carry out, is the deductive argument.

05:44

The main rule of a deductive arguments is: if your premises are true, then your conclusion must be true.

05:49

And knowing that something is actually true is very rare, and awesome.

05:54

So, here’s a boiled-down version of a good deductive argument:

05:56

Premise 1: All humans are mortal.

05:58

Premise 2: Socrates is a human.

06:00

Conclusion: Socrates is mortal.

06:03

This kind of reasoning, where one fact leads to another, is called entailment.

06:06

Once we know that all humans are mortal, and that Socrates is a human, those facts entail that Socrates is mortal.

06:12

Deduction begins with the general – in this case, what we know about human mortality – and

06:15

reasons down to the specific – Socrates in particular.

06:18

What’s great about deductive arguments is that the truth of the premises must lead to

06:22

the truth of the conclusion.

06:24

When this happens, we say that the argument is valid – there’s just no way for the

06:27

conclusion to be false if the premises are true.

06:30

Now check out this argument:

06:31

All humans are mortal. Socrates is a human. Therefore, Socrates was Plato’s teacher

06:36

That argument is invalid, because nothing about human mortality can prove that Socrates was Plato’s teacher.

06:41

As you might have noticed, there are plenty of mortal humans who never taught Plato.

06:45

What’s interesting, though, is that this argument does happen to have a true conclusion,

06:50

which leads us to another issue. And that is:

06:52

Validity is not the same as truth.

06:55

All β€˜valid’ really means is that if the premises are true, then your conclusion can’t be false.

06:59

But that doesn’t mean that your premises prove your conclusion to be correct.

07:03

Like, in the case of whether Socrates was Plato’s teacher, the premises are true,

07:06

and the conclusion is true, but the argument is still not valid -- because the premises

07:10

don’t in any way prove the conclusion. It just happens to be true.

07:14

So, if your premises don’t guarantee the truth of your conclusion, then you can end up with some really crappy arguments.

07:19

Like this one: - All cats are mammals

07:21

- I’m a mammal - Therefore, I’m a cat

07:23

As much as part of me would like to be my cat, this is invalid because the conclusion

07:27

doesn’t entail from the premises…at all.

07:30

I mean, all cats are mammals, but all mammals aren’t cats. Which means there are such

07:34

things as non-cat mammals, which I am just one example of.

07:38

And it probably goes without saying, but you can have a perfectly valid argument and still have a false

07:41

conclusion, if any of your premises are false. For example: - All humans have tails

07:46

- My brother John is a human - Therefore, John Green has a tail!

07:49

The argument is totally valid! – Because the premises entail the conclusion! The reasoning totally stands up!

07:55

It’s just that one of the premises is flawed.

07:57

Since I’m reasonably certain that John doesn’t have a tail -- I’ve seen him in a bathing

08:01

suit -- this argument is not deductively sound.

08:04

And a deductively sound argument is one that’s free of formal flaws or defects.

08:07

It’s an argument whose premises are all true, and that’s valid, which means its

08:11

conclusion is guaranteed to be true.

08:13

So, sound arguments should always be your goal.

08:15

The reason that deduction is prized by philosophers -- and lots of other important kinds of thinkers

08:20

-- is that it’s the only kind of argument that can give you a real certainty.

08:23

But it’s limited, because it only works if you’re starting with known, true premises, which are hard to come by.

08:29

And for what it’s worth, deductive truths are usually pretty obvious. They don’t tend

08:33

to lead us to startlingly new information, like the fact that I’m not a cat, or that John doesn’t have a tail.

08:39

So instead of starting with premises that are already certain, like deduction does,

08:42

you’re gonna have to know how to determine the truth of, and your confidence in, your premises.

08:47

Which means you’re going to have to acquaint yourself with the other species of arguments,

08:51

which we’re gonna do next time.

08:52

But today, we talked about the value of reason, the structure of arguments, and we took a

08:56

close look at one kind of argument: deductive reasoning.

08:59

This episode of Crash Course Philosophy is made possible by Squarespace. Squarespace

09:03

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09:13

at squarespace.com/crashcourse for a special offer.

09:16

Crash Course Philosophy is produced in association with PBS Digital Studios. You can head over

09:20

to their channel to check out amazing shows like The Art Assignment, The Chatterbox, and Blank on Blank.

09:25

This episode of Crash Course was filmed in the Doctor Cheryl C. Kinney Crash Course Studio

09:29

with the help of all of these amazing people and our Graphics Team is Thought Cafe.

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