How to Argue - Philosophical Reasoning: Crash Course Philosophy #2 Video Lecture | What is Philosophy - Science or Religion? - Self Help Learning

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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.
So, here’s a boiled-down version of a good
deductive argument:
Premise 1: All humans are mortal.
Premise 2: Socrates is a human.
Conclusion: Socrates is mortal.
This kind of reasoning, where one fact leads
to another, is called entailment.
Once we know that all humans are mortal, and that
Socrates is a human, those facts entail that Socrates is mortal.
Deduction begins with the general – in this
case, what we know about human mortality – and
reasons down to the specific – Socrates
in particular.
What’s great about deductive arguments is
that the truth of the premises must lead to
the truth of the conclusion.
When this happens, we say that the argument
is valid – there’s just no way for the
conclusion to be false if the premises are
true.
Now check out this argument:
All humans are mortal. Socrates is a human.
Therefore, Socrates was Plato’s teacher
That argument is invalid, because nothing about human
mortality can prove that Socrates was Plato’s teacher.
As you might have noticed, there are plenty
of mortal humans who never taught Plato.
What’s interesting, though, is that this
argument does happen to have a true conclusion,
which leads us to another issue. And that
is:
Validity is not the same as truth.
All ‘valid’ really means is that if the premises
are true, then your conclusion can’t be false.
But that doesn’t mean that your
premises prove your conclusion to be correct.
Like, in the case of whether Socrates was
Plato’s teacher, the premises are true,
and the conclusion is true, but the argument
is still not valid -- because the premises
don’t in any way prove the conclusion. It
just happens to be true.
So, if your premises don’t guarantee the truth of your
conclusion, then you can end up with some really crappy arguments.
Like this one:
- All cats are mammals
- I’m a mammal
- Therefore, I’m a cat
As much as part of me would like to be my
cat, this is invalid because the conclusion
doesn’t entail from the premises…at all.
I mean, all cats are mammals, but all mammals
aren’t cats. Which means there are such
things as non-cat mammals, which I am just
one example of.
And it probably goes without saying, but you can
have a perfectly valid argument and still have a false
conclusion, if any of your premises are false.
For example: - All humans have tails
- My brother John is a human
- Therefore, John Green has a tail!
The argument is totally valid! – Because the premises
entail the conclusion! The reasoning totally stands up!
It’s just that one of the premises is flawed.
Since I’m reasonably certain that John doesn’t
have a tail -- I’ve seen him in a bathing
suit -- this argument is not deductively sound.
And a deductively sound argument is one that’s
free of formal flaws or defects.
It’s an argument whose premises are all
true, and that’s valid, which means its
conclusion is guaranteed to be true.
So, sound arguments should always be your
goal.
The reason that deduction is prized by philosophers
-- and lots of other important kinds of thinkers
-- is that it’s the only kind of argument
that can give you a real certainty.
But it’s limited, because it only works if you’re starting
with known, true premises, which are hard to come by.
And for what it’s worth, deductive truths
are usually pretty obvious. They don’t tend
to lead us to startlingly new information, like the fact
that I’m not a cat, or that John doesn’t have a tail.
So instead of starting with premises that
are already certain, like deduction does,
you’re gonna have to know how to determine
the truth of, and your confidence in, your premises.
Which means you’re going to have to acquaint
yourself with the other species of arguments,
which we’re gonna do next time.
But today, we talked about the value of reason,
the structure of arguments, and we took a
close look at one kind of argument: deductive
reasoning.
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