Can there be a compatibility between a universal ethical system grounded in reason and an ethical system grounded in a social, evolutionary biology? This study will explore different philosophers from the rational and empirical (later sociobiological) side of the spectrum and search for any common grounds between them. If the outcome of the exploration, just as implied by several philosophers through time, seems really contradictory, the search will go on looking for any form of a complementary system where both views on ethical behaviour keep their value and don’t dominate one another. A historical overview will facilitate a clear comparison between several aspects of the rational and empirical movement. Two examples of an synthesis will be clarified. The first one will emphasize an evolutionary approach to ethics in a chronological setting. The other, is a multiple approach theory where different ethical systems can exist next to eachother, at the same time, still cooperating without dominating one another.