Agreed, entirely. But the social-science and system-science issues get confused by using ethically charged words like "decent." Modeling "decent" gets confusin

Agreed, entirely. But the social-science and system-science issues get confused by using ethically charged words like "decent." Modeling "decent" gets confusing without ways of measuring it. (I'll spare us a long digression on how slippery it can be to understand ethical / moral reasoning.) Do I leave parking spots for other people because I'm a "decent" person? I like to think so -- I like to think I put others' needs ahead of my own when I can -- but that's my business. From a systems point of view I do it to help control parking lot congestion. If I were a business owner and didn't leave convenient parking spots for others, I'd be deliberately adding to congestion near my business. That's a cost. What's the benefit? Example: Van Jacobson's slow-start / exponential-backoff algorithm to help prevent TCP endpoints from saturating routers. It's certainly possible to explain this to a roomful of undergrads as a "be nice" requirement on web servers and other sources of large TCP streams. But it's more productive to model it as part of a large-scale system to control congestion.