There's something that I'd like you to see.

(Video) Reporter: It's a story that's deeply unsettled

millions in China:

footage of a two-year-old girl

hit by a van and left bleeding in the street by passersby,

footage too graphic to be shown.

The entire accident is caught on camera.

The driver pauses after hitting the child,

his back wheels seen resting on her for over a second.

Within two minutes, three people pass two-year-old Wang Yue by.

The first walks around the badly injured toddler completely.

Others look at her before moving off.

Peter Singer: There were other people

who walked past Wang Yue,

and a second van ran over her legs

before a street cleaner raised the alarm.

She was rushed to hospital, but it was too late. She died.

I wonder how many of you, looking at that,

said to yourselves just now, "I would not have done that.

I would have stopped to help."

Raise your hands if that thought occurred to you.

As I thought, that's most of you.

And I believe you. I'm sure you're right.

But before you give yourself too much credit,

look at this.

UNICEF reports that in 2011,

6.9 million children under five

died from preventable, poverty-related diseases.

UNICEF thinks that that's good news

because the figure has been steadily coming down

from 12 million in 1990. That is good.

But still, 6.9 million

is 19,000 children dying every day.

Does it really matter

that we're not walking past them in the street?

Does it really matter that they're far away?

I don't think it does make a morally relevant difference.

The fact that they're not right in front of us,

the fact, of course, that they're of a different nationality

or race, none of that seems morally relevant to me.

What is really important is,

can we reduce that death toll? Can we save

some of those 19,000 children dying every day?

And the answer is, yes we can.

Each of us spends money

on things that we do not really need.

You can think what your own habit is,

whether it's a new car, a vacation

or just something like buying bottled water

when the water that comes out of the tap

is perfectly safe to drink.

You could take the money you're spending

on those unnecessary things

and give it to this organization,

the Against Malaria Foundation,

which would take the money you had given

and use it to buy nets like this one

to protect children like this one,

and we know reliably that if we provide nets,

they're used, and they reduce the number of children

dying from malaria,

just one of the many preventable diseases

that are responsible for some of those 19,000 children

dying every day.

Fortunately, more and more people

are understanding this idea,

and the result is a growing movement:

effective altruism.

It's important because it combines both the heart and the head.

The heart, of course, you felt.

You felt the empathy for that child.

But it's really important to use the head as well

to make sure that what you do is effective and well-directed,

and not only that, but also I think reason helps us

to understand that other people, wherever they are,

are like us, that they can suffer as we can,

that parents grieve for the deaths of their children,

as we do,

and that just as our lives and our well-being matter to us,

it matters just as much to all of these people.

So I think reason is not just some neutral tool

to help you get whatever you want.

It does help us to put perspective on our situation.

And I think that's why

many of the most significant people in effective altruism

have been people who have had backgrounds

in philosophy or economics or math.

And that might seem surprising,

because a lot of people think,

"Philosophy is remote from the real world;

economics, we're told, just makes us more selfish,

and we know that math is for nerds."

But in fact it does make a difference,

and in fact there's one particular nerd

who has been a particularly effective altruist

because he got this.

This is the website of the Bill & Melinda Gates Foundation,

and if you look at the words on the top right-hand side,

it says, "All lives have equal value."

That's the understanding,

the rational understanding of our situation in the world

that has led to these people

being the most effective altruists in history,

Bill and Melinda Gates and Warren Buffett.

(Applause)

No one, not Andrew Carnegie, not John D. Rockefeller,

has ever given as much to charity

as each one of these three,

and they have used their intelligence

to make sure that it is highly effective.

According to one estimate, the Gates Foundation

has already saved 5.8 million lives

and many millions more, people, getting diseases

that would have made them very sick,

even if eventually they survived.

Over the coming years, undoubtably the Gates Foundation

is going to give a lot more,

is going to save a lot more lives.

Well, you might say, that's fine if you're a billionaire,

you can have that kind of impact.

But if I'm not, what can I do?

So I'm going to look at four questions that people ask

that maybe stand in the way of them giving.

They worry how much of a difference they can make.

But you don't have to be a billionaire.

This is Toby Ord. He's a research fellow in philosophy

at the University of Oxford.

He became an effective altruist when he calculated

that with the money that he was likely to earn

throughout his career, an academic career,

he could give enough to cure 80,000 people of blindness

in developing countries

and still have enough left

for a perfectly adequate standard of living.

So Toby founded an organization

called Giving What We Can to spread this information,

to unite people who want to share some of their income,

and to ask people to pledge to give 10 percent

of what they earn over their lifetime

to fighting global poverty.

Toby himself does better than that.

He's pledged to live on 18,000 pounds a year --

that's less than 30,000 dollars --

and to give the rest to those organizations.

And yes, Toby is married and he does have a mortgage.

This is a couple at a later stage of life,

Charlie Bresler and Diana Schott,

who, when they were young, when they met,

were activists against the Vietnam War,

fought for social justice,

and then moved into careers, as most people do,

didn't really do anything very active about those values,

although they didn't abandon them.

And then, as they got to the age at which many people

start to think of retirement, they returned to them,

and they've decided to cut back on their spending,

to live modestly, and to give both money and time

to helping to fight global poverty.

Now, mentioning time might lead you to think,

"Well, should I abandon my career and put all of my time

into saving some of these 19,000 lives

that are lost every day?"

One person who's thought quite a bit about this issue

of how you can have a career that will have

the biggest impact for good in the world is Will Crouch.

He's a graduate student in philosophy,

and he's set up a website called 80,000 Hours,

the number of hours he estimates

most people spend on their career,

to advise people on how to have the best,

most effective career.

But you might be surprised to know

that one of the careers that he encourages people to consider,

if they have the right abilities and character,

is to go into banking or finance.

Why? Because if you earn a lot of money,

you can give away a lot of money,

and if you're successful in that career,

you could give enough to an aid organization

so that it could employ, let's say, five aid workers

in developing countries, and each one of them

would probably do about as much good

as you would have done.

So you can quintuple the impact

by leading that kind of career.

Here's one young man who's taken this advice.

His name is Matt Weiger.

He was a student at Princeton in philosophy and math,

actually won the prize for the best undergraduate philosophy thesis

last year when he graduated.

But he's gone into finance in New York.

He's already earning enough

so that he's giving a six-figure sum to effective charities

and still leaving himself with enough to live on.

Matt has also helped me to set up an organization

that I'm working with that has the name taken

from the title of a book I wrote,

"The Life You Can Save,"

which is trying to change our culture

so that more people think that

if we're going to live an ethical life,

it's not enough just to follow the thou-shalt-nots

and not cheat, steal, maim, kill,

but that if we have enough, we have to share some of that

with people who have so little.

And the organization draws together people

of different generations,

like Holly Morgan, who's an undergraduate,