Definition of cynicism?

[vaneramos]

Recently, on LJ I believe, I saw a quoted definition of cynicism, something like this: "The belief that everyone is naturally motivated by selfishness." The LJer (or his quotation) went on to elaborate that this is not necessarily a bad thing, that it allows us to have more reasonable expectations of others, and that genuine altruism may be treated with highest regard.

I might have seen this on a friend's or friend-of-friend's info page or website. I only gave it passing notice, but the thought has stuck with me since last week. I want to find the source for the sake of reference. If you recognize it and can suggest where I saw it, that might be an act of altruism.