Imagine you're watching a runaway trolley barreling down the tracks straight towards five workers who can't escape.
You happen to be standing next to a switch that will divert the trolley onto a second track.
Here's the problem.
That track has a worker on it, too, but just one.
What do you do?
Do you sacrifice one person to save five?
This is the trolley problem, a version of an ethical dilemma that philosopher Philippa Foot devised in 1967.
It's popular because it forces us to think about how to choose when there are no good choices.
Do we pick the action with the best outcome or stick to a moral code that prohibits causing someone's death?
In one survey, about 90% of respondents said that it's okay to flip the switch, letting one worker die to save five, and other studies, including a virtual reality simulation of the dilemma, have found similar results.
These judgments are consistent with the philosophical principle of utilitarianism which argues that the morally correct decision is the one that maximizes well-being for the greatest number of people.
The five lives outweigh one, even if achieving that outcome requires condemning someone to death.
But people don't always take the utilitarian view, which we can see by changing the trolley problem a bit.
This time, you're standing on a bridge over the track as the runaway trolley approaches.
Now there's no second track, but there is a very large man on the bridge next to you.
If you push him over, his body will stop the trolley, saving the five workers, but he'll die.
To utilitarians, the decision is exactly the same, lose one life to save five.
But in this case, only about 10% of people say that it's OK to throw the man onto the tracks.
Our instincts tell us that deliberately causing someone's death is different than allowing them to die as collateral damage.
It just feels wrong for reasons that are hard to explain.
This intersection between ethics and psychology is what's so interesting about the trolley problem.
The dilemma in its many variations reveal that what we think is right or wrong depends on factors other than a logical weighing of the pros and cons.
For example, men are more likely than women to say it's okay to push the man over the bridge.
So are people who watch a comedy clip before doing the thought experiment.
And in one virtual reality study, people were more willing to sacrifice men than women.
Researchers have studied the brain activity of people thinking through the classic and bridge versions.
Both scenarios activate areas of the brain involved in conscious decision-making and emotional responses.
But in the bridge version, the emotional response is much stronger.
So is activity in an area of the brain associated with processing internal conflict.
Why the difference?
One explanation is that pushing someone to their death feels more personal, activating an emotional aversion to killing another person, but we feel conflicted because we know it's still the logical choice.
"Trolleyology" has been criticized by some philosophers and psychologists.
They argue that it doesn't reveal anything because its premise is so unrealistic that study participants don't take it seriously.
But new technology is making this kind of ethical analysis more important than ever.
For example, driver-less cars may have to handle choices like causing a small accident to prevent a larger one.
Meanwhile, governments are researching autonomous military drones that could wind up making decisions of whether they'll risk civilian casualties to attack a high-value target.
If we want these actions to be ethical, we have to decide in advance how to value human life and judge the greater good.
So researchers who study autonomous systems are collaborating with philosophers to address the complex problem of programming ethics into machines, which goes to show that even hypothetical dilemmas can wind up on a collision course with the real world.
To empower girls, you need to educate them.
That was my dream.
And so I built a school, and in the process, I learned something much bigger.
When you empower a girl, you transform a community.
School is just a start.
I grew up in rural Kenya in a small village called Enoosaen.
I was the first of eight children, and I spent my childhood helping my mother cook, clean, farm and take care of my siblings.
Like other Maasai girls, I was engaged from a very young age to be married.
But as I reached puberty, I underwent female genital mutilation, known as FGM.
This picture shows some of the tools that are used to perform FGM on girls.
FGM was supposed to mark the end of my childhood and, by extension, my education.
But I negotiated with my father in order to stay in school -- even after going through FGM.
Years later I went to university.
And in order to get my community's support, I promised to come back one day to repay that support.
But years later, when I went back to my village, not much had changed.
Girls were still going through FGM, still leaving school, still getting married to men older than their fathers and still having children when they're teenagers.
I did not want to see any more girls go through that.
That's when I knew what I needed to do to give back to my community.
I built a school just for girls so that they can be free from FGM and early marriage.
At my first enrollment -- (Applause and cheers) At my first enrollment, I had hoped for 10 girls.
100 came.
(Cheers and applause) I started to realize just how big this dream was, and soon I learned that my school could be the foundation -- but it wasn't going to be enough.
So that first year, I enrolled these 30 girls.
Some had been abused, others were orphans, and some came from families that are very traditional, that had never sent any girl to school.
So school started.
Though the girls seemed excited to be there, they were having difficulty staying awake.
What was going on?
They had a teacher, they had books, there was a new classroom on the way, but ...
They were determined to be there, but they had no energy.
Then I realized they were hungry, so I quickly found a cook and food.
Soon thereafter, I learned that a classroom was not enough.
I needed a boarding school.
Not only were the girls tired and hungry from chores and long walks to school and back home, they were also not safe.
It's a sad truth, but girls are often assaulted, raped and even kidnapped on their way to school.
So before a girl could learn math or history, she needed to feel safe, she needed to be rested and be well-nourished.
So let me tell you about some of my girls.
This is Faith.
Faith comes from a very traditional family in the community.
Her older sister had already gone through FGM and already married, but Faith was so determined.
She really loved learning, and she wanted to come to my school when she heard about it.
So she asked her father, her mother -- anyone to bring her to my school.
They all refused.
Faith did something very brave.
She stole an egg from her mother's house, went to the market, sold the egg and bought a single pencil.
Then she walked five miles, clenching that pencil, trying to enroll.
She arrived -- (Applause) She arrived tired and hungry, but determined.
I listened to her story, and we enrolled her in my school.
But getting into my school was only just the start.
Faith needed food, she needed medicine, she needed counseling -- all of which we provided.
And she also met adults who already believed in her.
Supported by this community, Faith was ready to learn.
This is Faith.
Six months of schooling, now she's a happy sixth grader who dreams of becoming a pilot someday, and her family now supports her, and best of all, her younger sisters will follow in her footsteps.
(Applause) Child marriage is expected to cost the global economy trillions of dollars over the next 15 years.
We can talk numbers, but in a real lifetime, what child marriage will cost my village is the doctor, the teacher, the entrepreneur, the true partner our men will need in the future ...
real ways women can help us lift out of poverty.
So I came to realize once again, as I did when I needed help to go to university, that while I could dream or have a dream, I could not make it come true all by myself.
So I went back to the elders who helped me more than a decade ago.
I needed their support once again if I was going to be successful.
So I formed a community board with religious leaders, parents and some teachers from other schools.
I needed allies in the government and in the community to help advance my goal.
I needed especially the support of the chief to help me enforce the no-FGM policy in my school.
At first he was resistant, but I persisted -- (Laughter) and now he's our greatest ally.
(Applause) I also needed the fathers.
That brings me to Linet.
Linet's father, Momposhi, did not believe in the education of girls.
In fact, he himself never went to school.
But Linet's mother believed in Linet and brought her to enroll in my school, and I knew she belonged with us.
I just had to find a way to get Momposhi to believe in Linet, too.
So I used the pretense of revealing Linet's grade to get Momposhi to come.
He came, and he started noticing his daughter being promising as a student.
With each visit, he built a strong relationship with his daughter -- noticing not just her grades but also accepting her as someone with full potential.
So when Linet was accepted in one of the top national high schools after eighth grade, Momposhi was bursting with pride and went around the village telling everyone how proud and how smart his daughter was.
(Laughter) Can you imagine?
He brought Linet to the new school himself.
It was the first time either of them had ever been to Nairobi.
Today Linet is studying at university in Australia -- (Applause and cheers) and Momposhi is our greatest advocate in the community.
I also brought mothers to the table, including my own.
That's my mother in one of our training programs.
And our mothers are involved in the education of their own children.
I also brought grandmothers into the mix.
(Laughter) In my community, grandmothers are the proud keepers of our stories and cultures, and I wanted my girls to learn and embrace our rich Maasai culture.
Today, grandmothers do story time with the girls, and it's a beautiful way our community remains connected.
I also ...
started working with the boys!
(Laughter) What would happen if the boys grew up with the same mindset as their fathers before them?
I'll tell you, not much will change.
So I enlisted support from an organization called I'm Worth Defending: a group of young, progressive leaders led by Alfred and George.
Together we created a training program for boys and girls who could not attend my school, sharing vital information about gender equality, health and human rights.
Today we have reached over 10,000 boys and girls and counting.
(Applause) It turns out it truly does take a village to make this kind of a dream come true.
(Laughter) That's what you're seeing today, where nearly 400 girls have not gone through FGM in my village, in a region where nearly 80 percent of women have been cut.
Believe me, these girls, they are sharing their experiences with their sisters, their cousins and their friends.
They're so interested.
Over time, this is becoming the new normal and it's being embraced by the same, same community -- my community.
So what does transforming communities mean to Kenya?
President Obama visited Kenya in 2015, and he met with representatives from organizations trying to help improve communities.
Guess what?
He met Linet!
(Laughter) (Applause) Together they talked about a Kenya where all girls have the same opportunities, where Linet is a leader and where communities like Enoosaen are thriving because its members -- all its members -- have opportunities.
Helping the communities see that each daughter is a treasure, every sister is full of potential, and helping every single girl see that value in herself.
There is no limit to what that future will cost.
Not every girl who comes to my school will be a PhD, but every single one of them will achieve her full potential and will become an advocate for her children and her grandchildren for years to come.
Today my dreams are informed by what I learned from them and what I've learned from you.
My journey led me out of Enoosaen and back again.
And in the process, I was embraced by the world, and you have become my village.
So I make a new promise to you, my elders, my sisters and my friends, that I am going to keep dreaming and keep going until girls like Linet and Faith achieve their dreams and I see mine: that all communities give every single woman and every single girl their dreams come true.
Thank you.
(Applause and cheers) Thank you, thank you.
(Applause and cheers)
This is my favorite place on earth, Salar de Uyuni in Bolivia.
And when it's covered in a thin layer of water, it reflects the clouds.
There are days when you feel as if you're floating among the clouds.
But there are days when the horizon disappears; there's no longer a top or a bottom.
You feel immersed in something bigger.
It was there that one night I woke up from a dream, and I saw that the stars were also reflected on the water.
And that wasn't a dream.
It was as if you could walk among the stars.
With every step I took, the stars reverberated under my feet.
It was like I was floating in the universe among clouds of galaxies.
But what's floating there today are not just clouds of galaxies but also clouds of plastic.
These are the footprints we're leaving on the planet.
They're signs of an era in which the behavior of some humans is making a global impact on our ecosystems.
This era is called the Anthropocene.
There's also another type of toxic clouds that float in the air, like the ones that form from carbon dioxide emissions and from the burning of fossil fuels -- oil, carbon, gas -- clouds that, when we see them, pollute our dreams.
I don't know about all of you, but I've always dreamed of floating among the clouds.
Maybe today we can imagine together other types of clouds, clouds we can live with.
If you're wondering about that photo, I'll explain: it looks like a collage or photomontage -- something weird.
No; it's reality.
But sometimes I ask myself: What is reality?
According to Alexander Kluge: "Human beings are not interested in reality.
They can’t be; it’s part of the human essence.
They have desires.
These desires are totally opposed to any form of reality.
They prefer to lie than to become divorced from their desires."
But how can we learn to float among the clouds?
As an artist, I thought we could start building a flying museum.
You're probably wondering: With plastic bags?
In 2007, with a community of people all over the world, we began to collect used plastic bags -- not new ones.
And we washed them, we cut them up, we glued them together, and we began to draw on them, creating a huge canvas.
We made a collection of drawings, of personal stories and of friendships.
And when you join them, bend them and fold them, it creates a space full of air.
When the sun comes up from the horizon, the museum rises up to the sky.
That's why we call it, "The Aero-Solar Museum."
And from this simple idea, we learned how to float in the air in a radically new way, without using any type of fuel.
The difference in temperature between the interior and the exterior is what makes us rise up.
That way, we don't use fossil fuels or helium or hydrogen; we don't use solar panels or batteries or motors.
We discovered a way that's simple, clean and accessible to the whole world to lift ourselves up.
I remember when I was at NASA in 2009 with 120 engineers.
You guys know, too, when you go up in a plane, the control panels are gigantic.
And what we're doing is really complex, and when I started coming in with the plastic bags, saying, "But we have a different way ..."
people had a hard time understanding the concept.
Seeing the power of this idea, we started to initiate a new era; one that would leave behind the violence of the Anthropocene and give way to a new era, which we call the "Aerocene" -- an era of ecological awareness, in which we learn to float together, live together in the air, and come to an ethical commitment with the atmosphere and with planet earth.
That's why I've brought this backpack today.
Let's see ...
OK.
This is a balloon that we also refer to as a sculpture.
And if it's sunny out tomorrow, we can go out and fly -- though, no, the weather in Vancouver isn't -- (Laughter) it's not very ...
very favorable.
So, what other features does it have?
It has sensors that, when it moves, make sort of drawings in the air.
It also has other sensors.
I always think that first you have to feel it, and then you can measure it; you need to hear the sounds of the atmosphere, of the climate, of the hot air, in order to then measure the ozone, the carbon dioxide.
We're developing these sensors together with different communities all over the world in order to reconnect with the climate, the temperature and the environment, because there are other species in the air; in these excursions towards the atmosphere, we're not alone.
The air is full of clouds of life.
We live at the bottom of an ocean of air.
And this same sculpture, this exact one in my hands, flew 375 miles -- 12 hours -- from Germany to Poland, on a fuel-free trip.
But it wasn't free from crossing borders.
The trip was much more complicated than what we imagined; air space is as regulated and militarized as land space.
To fly using the winds, the heat of the sun and the radiant energy of the earth is complex and beautiful.
But even more complex will be getting the permits to cross the air space of each of the different countries that we fly over using wind.
At COP21, the Paris Climate Conference, we presented these spherical sculptures that could transport us all over the world.
But how can we fly using the wind to arrive at our destination?
Together with MIT, we developed a program that predicts how we can navigate the wind highways.
For example, if I had to return to Berlin from Vancouver, the first thing I would need to do is choose an altitude.
At different altitudes, there are different directions and different speeds.
The red line is tomorrow and the orange, the day after tomorrow.
And there it goes.
You can see, the best day to fly back to Berlin -- so now, traveling using only wind -- is in six days.
And we can get to 105 miles from the center of Berlin without burning a single drop of fuel, being transported only by wind currents.
So we thought that these trajectories that we drew with the wind could become signatures, declaring "Independence from Fossil Fuels Day."
More and more of us are experiencing the air in a different way.
You're all familiar with Earth Day.
We think we should also celebrate Air Day: it's a pact that we make with the earth, an ethical commitment to the atmosphere.
But let's keep thinking and dreaming.
We've learned that the bigger the sculptures are, the more weight they can lift.
Remember, they rise up only with hot air that's been heated by the sun.
Using this approach, we can learn to build gardens in the air.
Could we one day live in a garden the size of the earth?
Could we live in an ecosystem floating among the clouds?
Answering these questions isn't just a technological challenge; it's a way to reexamine the freedom of movement between countries, and of overcoming the political, social, cultural and military restrictions of contemporary societies.
Because in the end, the air belongs to everybody and doesn't answer to any government.
(Applause) And like we said earlier, our imagination is the force that allows us to create these places.
This is an installation I did at the Metropolitan Museum of Art in New York.
It asks the question: What might these transnational spaces be like?
And once we inhabit those spaces, we need to learn how to move within them, to walk among the clouds, where every movement affects everyone else's movements; the body weight and proximity between people will cause the space to expand ...
or contract.
There we are, suspended 72 feet in the air.
When two or more people get too close together, even those farthest away are affected -- everyone falls to the same spot.
These are fragile ecosystems.
And it's between these spheres that we build nets that connect us.
There are moments when we have to face the void, and fear can paralyze us.
One of the most beautiful things about this exhibit is the sense of solidarity generated when we face these new "aero-graphs."
Finally, let me tell you one last story.
On July 16, 1945, on the White Sands of New Mexico, an atomic bomb was detonated for the first time.
As a result of this explosion, a cloud of radioactive particles disseminated all over the earth, marking the beginning of the Anthropocene era.
Seventy years later, on November 8, 2015, in the same place, another event occurred.
For the first time in history, we lifted a person into the air using only the sun, without burning any fossil fuels.
As the sun rose up above the horizon, we rose up, too, silently, slowly, with no explosions.
We felt as if gravity had been inverted; it wasn't pulling us toward the center of the earth, but toward the universe.
If Neil Armstrong said, when he walked on the moon, "That's one small step for man, one giant leap for mankind," perhaps what we ought to ask ourselves is: What steps do we need to take today?
In the Aerocene era, our steps are much smaller, but radically different; they're steps that began with a bag full of air and wishes, but that can carry us to independence from fossil fuels and the opportunity to celebrate Air Day; steps that won't leave footprints on other planets until we've learned to walk in the atmosphere of this one.
The landscapes are tiny and the steps are tiny, but I hope we can take them together.
And I'm sure that these steps will lead us much further than the moon, so we can learn to float with our feet on the ground.
Thank you.
(Applause)