This is a graph that represents the economic history of human civilization. [World GDP per capita over the last 200,000 years] There's not much going on, is there. For the vast majority of human history, pretty much everyone lived on the equivalent of one dollar per day, and not much changed. But then, something extraordinary happened: the Scientific and Industrial Revolutions. And the basically flat graph you just saw transforms into this. What this graph means is that, in terms of power to change the world, we live in an unprecedented time in human history, and I believe our ethical understanding hasn't yet caught up with this fact. The Scientific and Industrial Revolutions transformed both our understanding of the world and our ability to alter it. What we need is an ethical revolution so that we can work out how do we use this tremendous bounty of resources to improve the world. For the last 10 years, my colleagues and I have developed a philosophy and research program that we call effective altruism. It tries to respond to these radical changes in our world, uses evidence and careful reasoning to try to answer this question: How can we do the most good? Now, there are many issues you've got to address if you want to tackle this problem: whether to do good through your charity or your career or your political engagement, what programs to focus on, who to work with. But what I want to talk about is what I think is the most fundamental problem. Of all the many problems that the world faces, which should we be focused on trying to solve first? Now, I'm going to give you a framework for thinking about this question, and the framework is very simple. A problem's higher priority, the bigger, the more easily solvable and the more neglected it is. Bigger is better, because we've got more to gain if we do solve the problem. More easily solvable is better because I can solve the problem with less time or money. And most subtly, more neglected is better, because of diminishing returns. The more resources that have already been invested into solving a problem, the harder it will be to make additional progress. Now, the key thing that I want to leave with you is this framework, so that you can think for yourself what are the highest global priorities. But I and others in the effective altruism community have converged on three moral issues that we believe are unusually important, score unusually well in this framework. First is global health. This is supersolvable. We have an amazing track record in global health. Rates of death from measles, malaria, diarrheal disease are down by over 70 percent. And in 1980, we eradicated smallpox. I estimate we thereby saved over 60 million lives. That's more lives saved than if we'd achieved world peace in that same time period. On our current best estimates, we can save a life by distributing long-lasting insecticide-treated bed nets for just a few thousand dollars. This is an amazing opportunity. The second big priority is factory farming. This is superneglected. There are 50 billion land animals used every year for food, and the vast majority of them are factory farmed, living in conditions of horrific suffering. They're probably among the worst-off creatures on this planet, and in many cases, we could significantly improve their lives for just pennies per animal. Yet this is hugely neglected. There are 3,000 times more animals in factory farms than there are stray pets, but yet, factory farming gets one fiftieth of the philanthropic funding. That means additional resources in this area could have a truly transformative impact. Now the third area is the one that I want to focus on the most, and that's the category of existential risks: events like a nuclear war or a global pandemic that could permanently derail civilization or even lead to the extinction of the human race. Let me explain why I think this is such a big priority in terms of this framework. First, size. How bad would it be if there were a truly existential catastrophe? Well, it would involve the deaths of all seven billion people on this planet and that means you and everyone you know and love. That's just a tragedy of unimaginable size. But then, what's more, it would also mean the curtailment of humanity's future potential, and I believe that humanity's potential is vast. The human race has been around for about 200,000 years, and if she lives as long as a typical mammalian species, she would last for about two million years. If the human race were a single individual, she would be just 10 years old today. And what's more, the human race isn't a typical mammalian species. There's no reason why, if we're careful, we should die off after only two million years. The earth will remain habitable for 500 million years to come. And if someday, we took to the stars, the civilization could continue for billions more. So I think the future is going to be really big, but is it going to be good? Is the human race even really worth preserving? Well, we hear all the time about how things have been getting worse, but I think that when we take the long run, things have been getting radically better. Here, for example, is life expectancy over time. Here's the proportion of people not living in extreme poverty. Here's the number of countries over time that have decriminalized homosexuality. Here's the number of countries over time that have become democratic. Then, when we look to the future, there could be so much more to gain again. We'll be so much richer, we can solve so many problems that are intractable today. So if this is kind of a graph of how humanity has progressed in terms of total human flourishing over time, well, this is what we would expect future progress to look like. It's vast. Here, for example, is where we would expect no one to live in extreme poverty. Here is where we would expect everyone to be better off than the richest person alive today. Perhaps here is where we would discover the fundamental natural laws that govern our world. Perhaps here is where we discover an entirely new form of art, a form of music we currently lack the ears to hear. And this is just the next few thousand years. Once we think past that, well, we can't even imagine the heights that human accomplishment might reach. So the future could be very big and it could be very good, but are there ways we could lose this value? And sadly, I think there are. The last two centuries brought tremendous technological progress, but they also brought the global risks of nuclear war and the possibility of extreme climate change. When we look to the coming centuries, we should expect to see the same pattern again. And we can see some radically powerful technologies on the horizon. Synthetic biology might give us the power to create viruses of unprecedented contagiousness and lethality. Geoengineering might give us the power to dramatically alter the earth's climate. Artificial intelligence might give us the power to create intelligent agents with abilities greater than our own. Now, I'm not saying that any of these risks are particularly likely, but when there's so much at stake, even small probabilities matter a great deal. Imagine if you're getting on a plane and you're kind of nervous, and the pilot reassures you by saying, "There's only a one-in-a-thousand chance of crashing. Don't worry." Would you feel reassured? For these reasons, I think that preserving the future of humanity is among the most important problems that we currently face. But let's keep using this framework. Is this problem neglected? And I think the answer is yes, and that's because problems that affect future generations are often hugely neglected. Why? Because future people don't participate in markets today. They don't have a vote. It's not like there's a lobby representing the interests of those born in 2300 AD. They don't get to influence the decisions we make today. They're voiceless. And that means we still spend a paltry amount on these issues: nuclear nonproliferation, geoengineering, biorisk, artificial intelligence safety. All of these receive only a few tens of millions of dollars of philanthropic funding every year. That's tiny compared to the 390 billion dollars that's spent on US philanthropy in total. The final aspect of our framework then: Is this solvable? I believe it is. You can contribute with your money, your career or your political engagement. With your money, you can support organizations that focus on these risks, like the Nuclear Threat Initiative, which campaigns to take nuclear weapons off hair-trigger alert, or the Blue Ribbon Panel, which develops policy to minimize the damage from natural and man-made pandemics, or the Center for Human-Compatible AI, which does technical research to ensure that AI systems are safe and reliable. With your political engagement, you can vote for candidates that care about these risks, and you can support greater international cooperation. And then with your career, there is so much that you can do. Of course, we need scientists and policymakers and organization leaders, but just as importantly, we also need accountants and managers and assistants to work in these organizations that are tackling these problems. Now, the research program of effective altruism is still in its infancy, and there's still a huge amount that we don't know. But even with what we've learned so far, we can see that by thinking carefully and by focusing on those problems that are big, solvable and neglected, we can make a truly tremendous difference to the world for thousands of years to come. Thank you. (Applause)