In a 1974 paper, American philosopher Thomas Nagel famously wondered what it was like to be a bat. He concluded that we could never know what it was like to be a member of a different species – that the inner lives of animals are ultimately inaccessible to us. In Consciousness Explained (1991), Daniel C. Dennett, while acknowledging the influence of Nagel’s thought experiment, offered a rebuttal: any ‘interesting or theoretically important’ aspects of a bat’s consciousness, he argued, would be open to third-person observation. We could know, in other words, what it was like to be a bat – or a horse or goldfish for that matter – by simply looking.