The main concern of environmental philosophy has been to find value for nature. The thesis is an attempt to link a theory of nature, a theory of human nature and a theory of value, which Andrew Brennan stipulated for a viable environmental philosophy. The problem is set forward in Part I where a definition of nature is explored. The complexity of the task leads to a brief history of the concept of nature (after a criticism of other historical accounts by (...) three environmental philosophers) whereby two opposing explanations of nature and human nature are revealed: teleological and non-teleological. Part II traces the decline of teleological explanation in favour of non-teleological explanations and the development of two main explanations of human nature in relation to nature that are prevalent today: Ultra-Darwinism (a reductionist explanation of human nature) and postmodernism. An analysis of these two positions shows that neither have an adequate metaphysics for finding value for nature, and this is revealed by an examination of two different types of environmental philosophy influenced respectively by the two opposing views. In Part III the problem of values is discussed with particular emphasis on moral values. An argument for objective values based on objective knowledge is put forward as well as a theory of human nature which leads to the conclusion that teleological explanations link a theory of nature, a theory of human nature and a theory of value more satisfactorily than the non-teleological explanations of Ultra-Darwinism and postmodernism. The relevance of this conclusion to the problems of the environment is shown. (shrink)