What does it take to change the behaviour of people and businesses with respect to the environment? In the 1990's a group of social scientists gathered to discuss this question from their individual perspectives in disciplines ranging from marketing to theology and jurisprudence to psychology. Rather soon it became clear to them that they first needed to focus on basic assumptions about human motivation and rationality; otherwise it was impossible for say, the economist who regards individuals as calculating maximisers of utility, to understand the sociologist who presumes they are role-playing or norm-guided beings. Prompted by these debates on first principles, this volume gathers together some of the participants' perspectives on rationality. Wherever possible, the authors link the discussion of rationality to matching conceptions of nature and human attitudes toward it.