Leopold, Singer, and Callicott have three different interpretations of land conservation and what is a moral way for humans to treat the environment. Leopold offers a semi-altruistic version, calling for the protection in its entirety of all living things and everything on this earth. He refers to this as the biotic community. Callicott sees the interesting arguments that Leopold is making, but also believes that his claim, while good in theory, has holes in its logic for practical application. Singer takes a very different approach, looking at the earth from a utilitarian perspective. He will claim that God gave humans the earth to use for whatever purpose necessary to survive. All three authors' perspectives combine to provide the foundation for how an individual can look at the environment and how politics, ethics, and practices can be shaped for future generations. In Leopold's Ethics of the Earth, he begins by arguing that as human beings we have found at least two ethics on which we base our behaviors. First, ethics were applied at the individual level. Second, ethics shaped the interactions between man and society. Leopold believes that there is no ethical obligation in the larger society towards the environment. “There is not yet an ethic that deals with man's relationship with the earth, with the animals and plants that grow on it. … The extension of ethics to this third element of the human environment is, if I read the evidence correctly, an evolutionary possibility and an ecological necessity.” (Leopold pg. 2) Leopold calls for the land ethic to expand beyond humans, but include the land. “The land ethic simply broadens the boundaries of the community to include soils, waters, plants, and animals, or collectively: the… medium of paper… ld would be first, and Callicott goes so far as to argue that what is saying is extreme, but not in the wrong direction to ultimately achieve healthy conservation. Singer would argue that Leopold is at best an environmentalist, but probably an extremist calling for the total restructuring of human life to protect an unequal coexistence. Singer wouldn't necessarily call Callicott an extremist, but he would probably call him an environmentalist with an emphasis on the environment over human populations. All three authors have different opinions on conservation and the focus that should be placed on how people interact with the environment. Some are more extreme - Leopold - and others are clearly utilitarian - Singer - but all three lay out an idea of ​​why the environment should be regulated the way they believe, and the moral and ethical reasons for doing so..