Since for me moral demands necessarily flow from human psychology, I don't think we can be obliged to do something that we are not motivated in any way to do. In other words, I'm an "internalist" about morality.

The problem is that for almost any feature of humanity that you can name, whether it's the ability to suffer, whether it's the capacity to reason, whether it's having lives that can go better or worse, there are at least some other non-human animals that have all of these features as well. So to exclude non-human animals from the range of moral concern but to include all humans, just seems morally arbitrary.

If you look at the works psychologists have done about individual reports of wellbeing, what happens is that if you're poor, you are not happy. But once you achieve a certain level of material satisfaction then income has very little correlation with people's reported states of happiness, things like climate matter more, things like the culture of the country in which you're raised matter more and so the things really, let's face it, like individual temperament matter more than these things.

I think when it comes to climate change, the single most important thing in the world is for the United States' Congress to pass an effective bill that will put a price in carbon because if it starts costing something to emit carbon, this will provide an incentive, people do act on the basis to some extent of economic incentives to emit fewer greenhouse gases.

The density of human population combined with the development of powerful and largely unconstrained technology has given us the problems of the anthropocene and the serious possibility of self-caused extinction.

None of us are rational economic men as we're supposed to be portrayed in economic theory where mixes of passions, of desires, of moral principles, of self-deception, of altruism, of concern of others, of concerns for ourselves and an interest in our bank accounts. And social policies have to be responsive to the complexity of who we are as people or else, like the war on drugs, they're simply going to fail.

The most fundamental challenge of the anthropocene concerns agency. For those who lived the Enlightenment dream (always a minority but an influential one), agency was taken for granted. There were existential threats to agency (e.g., determinism) but philosophy mobilized to refute these threats (e.g., by defending libertarianism) or to defuse them (e.g., by showing that they were compatible with agency).