Trust can only be extended to a fairly small circle of friends and fellow citizens.

信任只能延伸到,一个极小的,朋友圈子及同邦公民。

耶鲁公开课 - 政治哲学导论课程节选

What this often--What this can be viewed as, as an extended version of selfish gene theory, which is that to the extent you're interconnected with other people you care about them more for purely selfish reasons.

其实我们可以把这个观点视为，自私基因理论的延伸，也就是说根据你和别人,互相联系的程度,你对他人的关心更多是因为自私的原因。

耶鲁公开课 - 心理学导论课程节选