Moral Portfolio Theory

From Psychology Today:

"Save a Plastic Bag, Help Save the World." The idea, of course, is that if we throw away fewer plastic bags, nature will benefit. Many such small virtuous actions can, in congregate, impart an enormous benefit. Also underlying the slogan is another idea, which is generally unexpressed explicitly yet a part of our collective folk psychology, that good behavior leads to a virtuous circle: doing one good deed puts us in a beneficial mindset that leads us to do more good deeds....Unfortunately, as psychological research has shown, human behavior doesn't work like that at all. On the contrary: single, small acts of virtuous behavior actually predispose us to behave worse.