"Garrett James Hardin was one of the first thinkers we would call an “ecologist” – arguably, he helped created the movement. His 1968 paper on The Tragedy of the Commons explained that if a shared resource — for example, a forest or a lake — was not centrally managed, its users would tend to destroy it over time as they acted rationally in their own interests. That idea led Hardin to his lifelong unpopular argument against continued human population growth. And as a result, Hardin was a supporter not only of all birth control methods, but also of sterilization. He also stood firmly against most forms of immigration, comparing immigration into a society with limited resources to an overcrowded lifeboat taking on new members. His position caused him to be ostracized by many mainstream political and academic thinkers."