Murray Shanahan in Aeon:
In 1984, the philosopher Aaron Sloman invited scholars to describe ‘the space of possible minds’. Sloman’s phrase alludes to the fact that human minds, in all their variety, are not the only sorts of minds. There are, for example, the minds of other animals, such as chimpanzees, crows and octopuses. But the space of possibilities must also include the minds of life-forms that have evolved elsewhere in the Universe, minds that could be very different from any product of terrestrial biology. The map of possibilities includes such theoretical creatures even if we are alone in the Cosmos, just as it also includes life-forms that could have evolved on Earth under different conditions.
We must also consider the possibility of artificial intelligence (AI). Let’s say that intelligence ‘measures an agent’s general ability to achieve goals in a wide range of environments’, following the definition adopted by the computer scientists Shane Legg and Marcus Hutter. By this definition, no artefact exists today that has anything approaching human-level intelligence. While there are computer programs that can out-perform humans in highly demanding yet specialised intellectual domains, such as playing the game of Go, no computer or robot today can match the generality of human intelligence.
But it is artefacts possessing general intelligence – whether rat-level, human-level or beyond – that we are most interested in, because they are candidates for membership of the space of possible minds. Indeed, because the potential for variation in such artefacts far outstrips the potential for variation in naturally evolved intelligence, the non-natural variants might occupy the majority of that space. Some of these artefacts are likely to be very strange, examples of what we might call ‘conscious exotica’.
In what follows I attempt to meet Sloman’s challenge by describing the structure of the space of possible minds, in two dimensions: the capacity for consciousness and the human-likeness of behaviour.