|dc.description.abstract||Ethical theories seem always to be rooted in some underlying theory of human nature, explicit or implicit: Understanding what kind of creatures humans are would appear to be a necessary precondition for drawing conclusions about how humans ought to live. In the 150 years since the publication of Darwin's Origin of Species, humanity's collective understanding of its own nature has grown increasingly rooted in evolutionary biology. However, a scientific theory of human nature is widely presumed to provide a basis only for factual claims about human nature, from which no value conclusions can be drawn: This presumption, if true, would permit only descriptions of evolved ethical behaviors and would deny the possibility of producing a genuinely prescriptive ethical theory rooted in evolutionary biology.
While I acknowledge the difficulty of any argument which attempts to bridge the gap between facts and values, I believe that this difficulty can be overcome. In my dissertation, I develop the foundation for a prescriptive evolutionary ethical theory as follows: The arguments offered by Aristotle, Kant and Mill for the foundations of virtue ethics, deontology and utilitarianism respectively all attempt to bridge the fact-value gap in the same basic fashion – by identifying what is, as a matter of fact, of intrinsic value to each and every human being. These fact-value bridging claims serve as foundational normative premises from which prescriptive conclusions can be justifiably derived, culminating in the universal prescriptive claims of their respective complete ethical theories. From an evolutionary perspective, the fitness benefits (and costs) to a given organism of its various possible circumstances and activities effectively comprise what is of intrinsic value (and disvalue) to that organism. Higher-level selective processes such as kin selection, reciprocal altruism and group selection can broaden the initially self-regarding character of what is of value to a given organism in a way that includes selected other organisms. In humans, the mechanisms of cultural selection expand what is of value to an individual human to include every other human, at least in a certain respect – which constitutes the core normative premise foundation for a prescriptive evolutionary ethical theory.||