There is considerable dispute over the nature of the relationship between ethics and the natural sciences. This thesis argues that ethics is substantially independent of the natural sciences because the appeals to the natural sciences fail to adequately justify moral judgements about human beings. Specifically, I argue that if appeals to the natural sciences are not adequate to justify the normative assessment of living organisms, then they are not adequate to justify moral judgements about human beings. I consider the following appeals to justify the normative assessment of living organisms. These include the appeals to: (1) typicality; (2) history; (3) what is natural; (4) natural selection; (5) functions; (6) development; (7) species; and (8) the experience of pleasure and pain. I claim that these appeals are inadequate for one or more of the following reasons. One, some versions of the appeals are incompatible with the natural sciences. Two, the appeals justify implausible and counterintuitive moral judgements. Three, the appeals fail to adequately determine what should occur in contrast to what occurs. Four, there are many different appeals which justify contrary moral judgements and no objective means within the natural sciences to privilege one appeal over another. Finally, five, for some appeals there are various parameters which determine what is justified, but there are no objective means within the natural sciences to justify any particular set of parameters over and against alternatives
