  In the diverse array of work investigating the nature of human values from
psychology, philosophy and social sciences, there is a clear consensus that
values guide behaviour. More recently, a recognition that values provide a
means to engineer ethical AI has emerged. Indeed, Stuart Russell proposed
shifting AI's focus away from simply ``intelligence'' towards intelligence
``provably aligned with human values''. This challenge -- the value alignment
problem -- with others including an AI's learning of human values, aggregating
individual values to groups, and designing computational mechanisms to reason
over values, has energised a sustained research effort. Despite this, no
formal, computational definition of values has yet been proposed. We address
this through a formal conceptual framework rooted in the social sciences, that
provides a foundation for the systematic, integrated and interdisciplinary
investigation into how human values can support designing ethical AI.
