Abstract

The primary challenge for generating a useful scientific definition of life comes from competing concepts of biological activity and our failure to make them explicit in our models. I set forth a three-part scheme for characterizing definitions of life, identifying a binary , a range , and a preference . The three components together form a proper activity in biology . To be clear, I am not proposing that proper activity be adopted as the best definition of life or even as a desirable definition for life. Instead, I am arguing that some notion of proper activity already exists within common scientific definitions. By making the implicit elements explicit, the notion can be analyzed to see whether it is useful and appropriate in the context of the biological sciences