[M]orality is founded in a sense of the contingency of the world, and it is powered by the ability to envisage alternatives. Imagination is central to its operations. The morally complacent person is the person who cannot conceive how things could have been different; he or she fails to appreciate the role of luck—itself a concept that relies on imagining alternatives. There is no point in seeking change if this is the way things have to be. Morality is thus based on modality: that is, on a mastery of the concepts of necessity and possibility. To be able to think morally is to be able to think modally. Specifically, it depends upon seeing other possibilities—not taking the actual as the necessary.

Colin McGinn, ‘Apes, Humans, Aliens, Vampires and Robots’, in Paola Cavalieri and Peter Singer (eds.), The Great Ape Project: Equality Beyond Humanity, New York, 1993, p. 147