Moral choice requires rationality, but a global environmental crisis created by our civilization makes it increasingly difficult to know what rationality is. Defining reason as the domination of nature is an essential part of the crisis, especially given the dependence of scientific research and technological innovation on corporate and government funding and interests. Yet with a multitude of radically different conceptions of selfhood, nature, ethical responsibility, the meaning of life (etc.), it is not clear what alternatives can take its place. Also, political shifts are erasing truth as a meaningful category of human understanding. At best, this chapter argues, we can evaluate the ultimate consequences of our separate conceptions of reason, remembering that even the identification of consequences will be subject to critical disagreements. A modicum of hope is found in how different cognitive and cultural communities (e.g., religion/science, Palestinians/ Israelis) are finding common ground because of common environmental threats.