What is life, and what is a machine? The ontology of bioengineering

In his Keynote address to the First Conference at Clemson University on Ethical Issues in Biomedical Engineering, George Bugliarello suggested that a most important ethical issue for bioengineering "is the positioning of the bio-machine interface." "Where," he asked, "should the biological organism end and the machine begin?" Central to this question of the limits of life and engineering is the more fundamental question of how life differs and how it is similar to a machine. This paper argues that until very recently, science, by its very nature, has treated life as if it were a machine, or has treated the parts of living systems as if they were machines. The distinctive feature of a machine is that its behavior is linear and hence predictable. On the other hand, living organisms may not be linear, but rather nonlinear systems. Thus, the interface between organism and machine may be conceived as the interface between nonlinear and linear systems.