There is a growing movement called effective altruism. It's important because it combines both the heart and the head.

Should one break in and free the animals? That is illegal, but the obligation to obey the law is not absolute. It was justifiably broken by those who helped runaway slaves in the American South, to mention only one possible parallel.

We don't usually think of what we eat as a matter of ethics. Stealing, lying, hurting people - these acts are obviously relevant to our moral character. In ancient Greece and Rome, ethical choices about food were considered at least as significant as ethical choices about sex.

The idea that we can actually have an impact on places more or less instantly, too, by responding in some way or not responding, I think, also makes it true.

Can we really believe that we are living a good life, an ethically decent life if we don't do anything serious to help reduce poverty around the world and help save the lives of children or adults who are likely to die if we don't increase the amount of aid we are giving.

The newspapers do little better. Their coverage of nonhuman animals is dominated by "human interest" events like the birth of a baby gorilla at the zoo, or by threats to endangered species; but developments in farming techniques that deprive millions of animals of freedom of movement go unreported.

By ceasing to rear and kill animals for food, we can make so much extra food available for humans that, properly distributed, it would eliminate starvation and malnutrition from this planet. Animal Liberation is Human Liberation too.