PETER SINGER: Great philosophers have tried to understand the world we're living in and have tried to think about how we ought to live. And I think these are really fundamentally important questions that any rational being ought to be interested in trying to find the answers to.

What are the fundamental principles about how we ought to act? Ought we to be looking at moral rules that we ought never to violate? Ought we to be trying to work out what rights beings have? Should we be looking at the consequences of our actions and use that as the ultimate criterion for deciding what's right and wrong? These questions are still questions we face today. They have no scientific answer; They're not about the nature of the universe in that way. They're about how we ought to live, which is a different type of question. And so I think it's particularly relevant to look at what philosophy and what philosophical discussions have contributed to our reflection and our thought about how we ought to live.

So my top three current ethical issues would be global poverty; climate change, which is clearly related to global poverty; and the way we treat animals, which I think is a hugely neglected issue that affects tens of billions of animals every year.

I think a question that you might use to shape your thinking around the issue of global poverty would be: What ought I to be doing to contribute to helping people in extreme poverty? Each person who asks that question, of course, is in a somewhat different situation, but I'm assuming that you're living in an affluent country and within that country you're not among the poorest in that country, so you're middle class in that country or above, so you have money to spare after providing for your all your basic needs and making some provision for the future. You spend money on luxuries that you don't need, if it ranges from buying a bottle of water when you could drink water that comes out of the tap and is free or maybe it's taking vacations or buying clothes when you've got plenty of clothes to keep you warm and decent. So if you're in that situation, then you can ask yourself: What ought to I be doing to consider myself an ethical person? Is it okay for me just to be living my life in my society and not doing anything for people who, through no fault of their own, are living in extreme poverty. And if the answer to that is no then you need to think about, well, what should I be doing? How much should I be doing?

With regard to climate change, perhaps the most pressing question is what can I do about this situation? I'm assuming that, like the overwhelming majority of scientists, you accept that climate change is real, that it's happening, that it is largely caused by human activities emitting greenhouse gases and that it's going to be catastrophic—if it's not checked it's going to have catastrophic results for billions of people on our planet. I believe there are two ways in which you can contribute. We can each contribute by trying to reduce our own greenhouse gas emissions, reducing activities that use fossil fuels and release carbon dioxide into the atmosphere. We all know about that. Perhaps riding a bike rather than driving a car or walking more or using public transport. Those kinds of things help. Not having your air conditioning on too low, too cool, when you don't need to and so on. But also we need to think and people are now thinking more about what we ought to be eating because meat is a major contributor to climate change, and so that's led a lot of people to become vegan or to become reducitarian, to reduce the amount of meat they're eating so they're only eating meats say two days a week rather than seven. And all of those things can help. But, it's still true that it's a bigger problem that I don't think will be solved by the action of individuals, so we need to act politically. We need to come together and put as much pressure as we can on our political leaders to take serious steps about this.

The most basic question that you can think about with regard to animals is: What should the moral status of animals be? What is it now? I think we all know that: Essentially, animals are things. Legally we own animals, they're property. The farmer owns the animals he or she raises. The laboratory, the corporation running the laboratory, owns the animals that they're using to test on. The fur farmer owns those animals. And they don't really have rights of their own. They don't have a moral status that says it's wrong to lock them up in small cages. It's wrong to raise them by whatever method will produce their flesh or their eggs or their milk most cheaply for humans to consume or to perform painful experiments on them or to slaughter them for their fur. They don't have that moral status. And so the first question is: Is that wrong? And I believe it is wrong. I think we're guilty of speciesism which is the analogy at the species level of racism at the race level and sexism at the level of relations between men and women. And just as we are trying to move past those long-lasting traditional prejudices against some races and against women, so it's time for us to move past the prejudice against beings who are not members of the species Homo sapiens, and to say if they can feel, if their lives can go well or badly, then we ought not to be ignoring those interests. We ought not to be sacrificing their interests just for our convenience or just to get animal products that we eat a little bit more cheaply. And then after that you need to think about: Should I be participating in these industries at all? Am I complicit in the suffering that's being inflicted on animals, especially in factory farms but in other forms of farming as well? Am I complicit in that when I buy those products? And, if so, does that mean that I need to stop buying them? That I need to move away from a lifestyle that consumes animal products and move closer to a vegan lifestyle or move all the way to a vegan lifestyle, if you can do that, which will mean that I'm no longer supporting these industries that are based on the cruel exploitation of animals? And, of course, will also mean that I'm contributing less to climate change.