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My name is Jennifer Nagel.

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I teach philosophy at the university of Toronto,

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and today I want to talk to you about knowledge.

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Knowledge is something human beings naturally crave,

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we spend a lot of time and effort

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trying to gain it, for example by

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watching videos like this one.

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We also have natural instincts to keep

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track of what other people do and don't know

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

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But it's suprisingly difficult to give a good

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explanation of the nature of knowledge itself,

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and to say how knowing that something is

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

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When we try to figure out what knowledge is,

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we encounter some interesting questions

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and paradoxes. This series explores these problems,

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and explains how philosophers have tried to solve them.

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This particular video will focus on some basic

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features of knowledge, features that any good

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theory of it should try to explain.

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So, what kinds of things can you know?

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

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

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a place, "Pierre knows Paris";

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or a language, "Alice knows french".

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But the most common way of using the verb

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

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speaking of someone knowing a fact, as in

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"Alice knows that it's raining outside".

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In this series we'll be focusing on this

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

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Sometimes this is called "knowledge-that",

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

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question words like "where" or "when".

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"Pierre knows when the party will start"

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or "Pierre knows where the party is".

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Knowing where the party is means knowing the

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

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

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

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a way of being latched on to a fact.

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It is thought that every language in the world

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has a word that works to translate this fact-grabbing

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sense of the word "to know".

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And this kind of global popularity is very rare,

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only about a hundred words are thought

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to be universal in this way.

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Around the world, words meaning "to know" are

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

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most common words in english for example.

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So we often find ourselves talking about

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knowledge, but when we say someone knows

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something, what do we mean?

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It can help to compare knowing and just believing.

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Consider these two sentences:

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

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

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We instinctively feel some difference between

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Alice and Pierre, but what is it?

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Actually, we'll see there's several possible

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points of contrast here.

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The first and easiest has to do with truth.

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If Pierre just believes that it's raining outside,

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

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rain has stopped, and he's fooled by the

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sound of water dripping from the trees.

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The things we believe are sometimes true

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and sometimes false.

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What we actually know on the other hand,

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

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

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While it sounds weird to say

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

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This is because attachment to the truth

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is built into the meaning of knows-that.

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Beyond truth, another key feature of

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knowledge is confidence.

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Let's suppose that Pierre is in a windowless

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

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He could suspect that it's still raining

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outside, even of he's not totally sure.

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

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no doubt. She's confident.

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So, is confident belief in a truth enough

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for knowing? Apparently not.

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There's at least one more thing we need.

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Imagine that Pierre is really pessimistic,

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he's always strongly convinced that

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things will go badly. He's often wrong,

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but sometimes he's right. Today he wakes up

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in a windowless room, aware that Alice has

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planned a picnic because the forecast was

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

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

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He's entirely confident that it's raining,

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

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

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right this time. Does Pierre actually know

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that it's raining outside?

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If he doesn't know, then it seems knowledge

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requires something more than confident

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belief in a truth. Feeling pessimistic isn't

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a good basis for judgements about the weather.

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Your judgement needs to have a good basis

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in order to count as knowledge.

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But what kind of basis counts as good?

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Do you have to be standing outside,

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getting wet? As you will see,

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in the upcoming videos on the analysis of

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knowledge, this is a controversial question.

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But before we get to that problem, we'll

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tackle a more basic problem: is knowledge even

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possible for us? Even in the best case

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scenario, when it feels like you're standing

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right outside, right in the rain, can you

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really know that it's raining outside?

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Could you be dreaming for example,

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on a clear night?

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This is the problem of skepticism,

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explored in the next video.

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The two following videos will explain

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possible solutions to skepticism.