1. A television nature programme some years ago contained a striking sequence in which a giant squid was under threat from some other creature (no doubt a human being with a video camera). The squid responded in a way that struck me immediately and powerfully as one of fear. Part of what was striking in this sequence was the way in which it was possible to see in the behaviour of a creature physically so very different from human beings an emotion that was so unambiguously and specifically one of fear. While I would guess that most who saw this film would see in the squid's response something similar to what I saw I cannot offer a description of that behaviour that might help to convince someone who has not seen the film and who is sceptical: a description such that they might agree that if it really did behave like that, then it was certainly correct to ascribe fear to it. That I cannot do so is not, I think, merely a reflection of my very limited descriptive powers. It is a reflection of the fact that there is no more fundamental description of the squid's response than ‘fleeing in fear’: no other form of description that underlies, and so might provide support for, this one. My aim in this essay is to establish this point and to bring out its significance for two very different ways in which philosophers have spoken of our ascriptions of sensations and emotions to non-human creatures.

In the first chapter of Animal Liberation, Peter Singer offers what he takes to be an essential preliminary to the argument of the rest of the book. If we are to show that we have a moral obligation not to cause unnecessary suffering to animals, we must, Singer suggests, first establish that animals are capable of suffering.