What are "Socially Responsible" and "Sustainable" Investing?

One of the best online discussions of this issue that I've found is at:
michaelbluejay.com
But the most common catch-phrase (which Parnassus Investments has branded) is "Doing well by doing good". For long-term investors, SRI & sustainable investing should pay off better than short-term attempts to game all the systems in which business is done, whether legal, regulatory, environmental, social, ethical or other systems, because eventually such gaming will catch up to the perpetrators. Need I say "BP"?
Having said that, you may be willing to sacrifice higher investment returns and/or incur higher management expenses to be sure your most important principles are honored. For example, CrueltyFree purports to be a website directory of companies that don't harm animals to develop, test & manufacture their goods. This makes sense to me because people who in their minds can turn animals into objects probably do the same with their customers.
Still, how do you tell what's SRI and what isn't? Last time I checked, over 90% of Fortune 500 companies were included in so-called Socially Responsible Mutual fund portfolios. I'm sympathetic; the sheer cost of deeply screening companies for portfolio selection- if "perfect" -would price any SRI fund manager out of the market.
Thankfully, the Internet has become the great equalizer. Virtually anyone can drill down into the inner workings of just about any corporation.
But what criteria do you use? I like William McDonough's three simple principles that by now we should have learned from nature (he's author of "Cradle to Cradle"):
1. Waste Equals Food. All materials used by living beings in nature are constantly returned to the earth and used as food [raw materials] for other living systems.
2. Rely on Solar Income. Nature does not mine from the past. Current solar energy powers the whole system. By mining from the past (coal, oil, gas) and stealing from the future (ocean dumping, depleting fisheries, heating the atmosphere) we are proving to ourselves that our lifestyles will be scaled back, sooner than later, whether we choose that or it is forced upon us.
3. Respect Diversity. An intricate web of relationships among millions of diverse organisms provides stability to ecosystems so that they do not collapse when calamities occur.
These may seem like kumbaya, warm & fuzzy ideals to some folks. But what they really are are admonitions, sober warnings about how the real world works. Anyone, any society, any corporation trying to get around these rules will ultimately fail miserably.
So, in terms of where to invest, I think the rare company that is diligently trying to follow these three principles will do very well in the long term. Hey, what do you know. My company does.