When I trust you in the sense of believing that your interests encapsulate mine in at least the matter with respect to which I trust you, we can, naturally, be said to share interests to some extent. We might share interests in two quite different ways. First, we may merely share them causally, because what serves your interest serves mine as well. Second, one of us may genuinely adopt the other's interests as our own (see further Hardin 1999c). If I love you, I may literally encapsulate your interests in mine to some extent in the sense that I value your happiness so much that I act as though for your benefit without full regard for my own benefit.

DEFINE: The passage distinguishes two distinct ways interests can be shared: causal overlap versus deliberate adoption of another's interests, as when love leads someone to value another's happiness.

Russell Hardin, Trust and Trustworthiness, loc. 656