The Golden Rule (a.k.a. the ethic of reciprocity) is summarized as “Do unto others as you would have them do unto you”. Commandments IV – X are specific examples of the application of The Golden Rule. The Golden Rule has been expressed in many ways in many different cultural settings. I therefore see it as principle that arises out of social necessity, even though it has the imprimatur of various religions.
“Doing unto others as they would do unto you” implies an accepted set of social norms, which go beyond actual harm (e.g., murder, theft). The norms arise gradually as close-knit groups (families, clans, tribes, ethnic groups) coexist over a period of time. Coexistence yields lessons about behaviors that are acceptable (they advance in-group trust and cooperation) and behaviors that are unacceptable (they undermine in-group trust and cooperation). So the norms will include not only obvious things like the prohibition of murder (though not killing in self-defense), but also what I call instrumental or signaling behaviors to show that one is a trustworthy member of the group who abides by its norms and can be counted on to advance the interests of the group. This latter phenomenon is disparigingly called “tribalism” by “cosmopolitan sophisticates”, even though they are extreme tribalists in their own right.
Behavioral signaling is an inevitable and invaluable feature of harmonious coexistence. You can probably think of many examples of the kinds of persons whom you wouldn’t trust, based on their mannerism, clothing, hair styles, tastes in music, and — above all – political views.
It is certainly possible and desirable to apply The Golden Rule to members of out-groups. (The Parable of the Good Samaritan is meant to encourage such behavior.) But, as President Reagan said famously about relations with the Soviet Union: “Trust, but verify.” In other words, remain wary. Overt friendliness can be a dangerous trap.
(See also “Real Americans“.)