My name is Jennifer Nagel.

I teach philosophy at the university of Toronto,

and today I want to talk to you about knowledge.

Knowledge is something human beings naturally crave,

we spend a lot of time and effort

trying to gain it, for example by

watching videos like this one.

We also have natural instincts to keep

track of what other people do and don't know

in order to make sense of what they're doing.

But it's suprisingly difficult to give a good

explanation of the nature of knowledge itself,

and to say how knowing that something is

true, differs from just thinking that it's true.

When we try to figure out what knowledge is,

we encounter some interesting questions

and paradoxes. This series explores these problems,

and explains how philosophers have tried to solve them.

This particular video will focus on some basic

features of knowledge, features that any good

theory of it should try to explain.

So, what kinds of things can you know?

The english verb "know" is used in several ways;

you can know a person, "Alice knows Pierre";

a place, "Pierre knows Paris";

or a language, "Alice knows french".

But the most common way of using the verb

"to know" is the way we use it when we're

speaking of someone knowing a fact, as in

"Alice knows that it's raining outside".

In this series we'll be focusing on this

knowing-a-fact sense of the verb "to know".

Sometimes this is called "knowledge-that",

but actually, along with "that", you can use

question words like "where" or "when".

"Pierre knows when the party will start"

or "Pierre knows where the party is".

Knowing where the party is means knowing the

answer to the question "where's the party?",

and that's going to be a fact, like the fact

that the party is at Alice's place. Knowledge is

a way of being latched on to a fact.

It is thought that every language in the world

has a word that works to translate this fact-grabbing

sense of the word "to know".

And this kind of global popularity is very rare,

only about a hundred words are thought

to be universal in this way.

Around the world, words meaning "to know" are

also very heavily used. It's one of the top ten

most common words in english for example.

So we often find ourselves talking about

knowledge, but when we say someone knows

something, what do we mean?

It can help to compare knowing and just believing.

Consider these two sentences:

1. "Alice knows that it's raining outside."

2. "Pierre believes that it's raining outside."

We instinctively feel some difference between

Alice and Pierre, but what is it?

Actually, we'll see there's several possible

points of contrast here.

The first and easiest has to do with truth.

If Pierre just believes that it's raining outside,

where he is, maybe he's wrong. Maybe the

rain has stopped, and he's fooled by the

sound of water dripping from the trees.

The things we believe are sometimes true

and sometimes false.

What we actually know on the other hand,

has to be true, or factual. So there's no problem saying

"Pierre believes it's raining, but it isn't."

While it sounds weird to say

"Alice knows it's raining, but it isn't."

This is because attachment to the truth

is built into the meaning of knows-that.

Beyond truth, another key feature of

knowledge is confidence.

Let's suppose that Pierre is in a windowless

room, and he's been there for an hour.

He could suspect that it's still raining

outside, even of he's not totally sure.

But if Alice knows that it's raining, she has

no doubt. She's confident.

So, is confident belief in a truth enough

for knowing? Apparently not.

There's at least one more thing we need.

Imagine that Pierre is really pessimistic,

he's always strongly convinced that

things will go badly. He's often wrong,

but sometimes he's right. Today he wakes up

in a windowless room, aware that Alice has

planned a picnic because the forecast was

for sunny weather. "It's going to be terrible",

he thinks. "I'm sure it's already raining right now".

He's entirely confident that it's raining,

although he can't actually see or hear the rain.

And let's say by chance it turns out he's

right this time. Does Pierre actually know

that it's raining outside?

If he doesn't know, then it seems knowledge

requires something more than confident

belief in a truth. Feeling pessimistic isn't

a good basis for judgements about the weather.

Your judgement needs to have a good basis

in order to count as knowledge.

But what kind of basis counts as good?

Do you have to be standing outside,

getting wet? As you will see,

in the upcoming videos on the analysis of

knowledge, this is a controversial question.

But before we get to that problem, we'll

tackle a more basic problem: is knowledge even

possible for us? Even in the best case

scenario, when it feels like you're standing

right outside, right in the rain, can you

really know that it's raining outside?

Could you be dreaming for example,

on a clear night?

This is the problem of skepticism,

explored in the next video.

The two following videos will explain

possible solutions to skepticism.