Moral circle expansion

Moral circle expansion is an increase over time in the number and type of entities given moral consideration.^[1] The general idea of moral inclusion was discussed by ancient philosophers and since the 19th century has inspired social movements related to human rights and animal rights. Especially in relation to animal rights, the philosopher Peter Singer has written about the subject since the 1970s, and since 2017 so has the think tank Sentience Institute, part of the 21st-century effective altruism movement. There is significant debate on whether humanity actually has an expanding moral circle, considering topics such as the lack of a uniform border of growing moral consideration and the disconnect between people's moral attitudes and their behavior. Research into the phenomenon is ongoing.