How did Alan Gibbard explain the social value of speaking about morality as if it were objective?

In his work Wise Choices, Apt Feelings (1990), the American philosopher Alan Gibbard addressed the social function of moral discourse from an expressivist perspective. While he maintained that moral judgments are expressions of attitude rather than statements of objective fact, he argued that framing morality as a realm of objective truth serves a vital social purpose.12

According to Gibbard, speaking about morality in objectivist terms helps individuals coordinate their behavior with other members of their group. Because this social coordination provides clear survival value, humans have naturally evolved a tendency to think and communicate about moral issues as if they were objective facts. Consequently, Gibbard concluded that there is no necessity to alter this mode of discourse, suggesting that attempting to do so would actually be harmful to human social cohesion.12