One might think of the development of animal ethics in the past five decades or so as coming in three, often overlapping, waves. The first wave, rising in the 1970s and cresting in the 1980s, was dominated by a debate between utilitarians and those who took a deontological approach, emphasising adherence to moral rules rather than expedience. Maximise satisfied preferences, whether human or animal, advised the utilitarian Peter Singer. No, countered Tom Regan, respect the inherent value of animals. In the 1990s came the second wave, with different kinds of ethical theories being brought to bear on the question of what we owe animals. This decade saw virtue-ethical, contractualist and care-ethical approaches to the treatment of animals being developed. The third wave was characterised by an expansion in the concept of the animal. In earlier waves there was, sometimes, a tendency to think of the welfare of animals simply in terms of the amount of pleasure and pain in their lives. The third wave has been shaped by the realisation that there is a lot more to animals’ lives than simply pleasure and pain. Martha Nussbaum’s new book, Justice for Animals, neatly incorporates both second- and third-wave concerns.

Nussbaum puts forward a ‘capabilities approach’ (CA). For Nussbaum, ‘Central Capabilities … are … substantial freedoms, or opportunities for choice and action in areas of life that people in general have reason to value. Capabilities are core entitlements, closely comparable to a list of fundamental rights.’ In humans, these