Trust is not, as altruism may be, a motivation that we must use sparingly because we have limited amounts of it. It is a cognitive judgment that depends on perceived facts. It may or may not be in short supply, but using it—that is to say, acting on it—does not reduce the supply. In some contexts people can trust one another across broad ranges of issues. Indeed, establishing trust in one area might lead to expanding it to other areas by generating diversified or higher levels of trustworthiness. Hence trust can build on trust.

XREF: Contrasts with altruism, which is treated as a depletable motivation — connects with any resource-scarcity framing of social capital.

Russell Hardin, Trust and Trustworthiness, loc. 516