Part of the claim in each case seems to be that one just knows there is something else at stake—something moral or psychological or whatever. This putative fact recommends that we try to understand how or why someone comes to think of his or her own actions as other than rational. … Oddly, however, there is not “a” case for an extrarational notion of trust. Indeed, there is little analytical agreement at all on any notion of trust, other than perhaps a residual interest notion. What case there is for something beyond this residual is essentially a cluster of descriptive claims about trusting behavior. The case is that it seems that more than the self-interest of the trusted is involved in the commitments of the truster.

DEFINE: Clarifies the 'residual interest notion' of trust versus the extrarational notion built on descriptive claims about trusting behavior.

Russell Hardin, Trust and Trustworthiness, loc. 368