Increasingly both environmentalists and animal ethicists recognize the enormous destruction caused by animal agriculture.

The only way major change in environmental policy is going to happen, the only way, is if there is a very strong, very active popular movement that demands it and such a movement would be unparalleled because it would be a popular movement that says, "Raise our taxes so that we change our behavior."

Many environmental questions are in a deep way philosophical, despite our penchant for treating them as if they were only technological, economic, or whatever.

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.

Some philosophers have begun writing sympathetically about predator elimination as a way of reducing animal suffering. From an environmental perspective this is somewhere between naïve and potentially disastrous.

Bentham spent much of his life writing constitutions and proposing legal reform in the light of his utilitarianism. The evaluation of particular acts was hardly his concern. The psychology of his day was hedonistic and he worked in that framework and passed it on to Mill, but it is clear as day that Mill was not a hedonist in the sense in which we use that term today, though he used the language of pleasure and pain to express his views.

Ethics is prescriptive and can change behavior, but usually only at the margins.