This thesis focuses on the ethical dimension of sustainable development as described in the Bruntland report. According to this report, we do have certain moral obligations to future generations. This thesis asks whether traditional moral philosophy, such as utilitarian and contractarian theories, can justify moral obligations to future generations, and if they can serve as ethical frameworks for sustainable development. The basic idea with sustainable development is to create a balance between society, the environment and the economy. If the environment is ascribed instrumental value, which is the case with traditional moral philosophy then there is no balance, because its value are based on whatever value the society and the economy is willing to give the environment. I will argue that the proper ethical framework for sustainable development is an ethical framework, based on Aldo Leopold's land ethic. This framework gives the environment a value on its own regardless to its usefulness to humans, which makes it possible to justify sustainable development as a balance between the economy, society and, the environment.