Smith - "Everyone always acts in their own best self-interest" (psychological egoism)
Jones - "What about a soldier who throws himself on a grenade? Or a bodyguard who takes a bullet for his employer?"
Smith - "They derive ego dividends for doing so."
Jones - "But they're killed doing it! How is it in one's self-interest to die for some small addition to one's self-esteem?"
Smith - "It's more than self-esteem: it's the preservation of their values and mindset. When the alternative is to duck for cover and let someone else die, many people would say that they couldn't live with themselves if they were to display such cowardice. Ergo, they die to protect their belief in who they are, which is the ultimate expression of self-interest."
Jones - "But it's deeply irrational to preserve one's self by destroying one's self. Wouldn't the highest rule of self-interest be self-preservation? Besides, if self-interest is the defining motive for everyone, wouldn't their belief in who they are be defined by self-interest?"
Smith - "Now look, you..."
Jones - "How then, can anyone's identity incorporate altruism or self-sacrifice?"
Smith - "It may be in one's self-interest to view oneself as non-self-interested."
Jones - "Doesn't such a view of oneself lead one into destructive alternatives like throwing yourself on a grenade or living with cowardice?"
Smith - "It may."
Jones - "Then self-interest acts against itself."
Smith - "I never said that self-interest was the smartest way to go..."