Only a living entity can have goals or can originate them. And it is only a living organism that has the capacity for self-generated, goal-directed action. On the physical level, the functions of all living organisms, from the simplest to the most complex—from the nutritive function in the single cell of an amoeba to the blood circulation in the body of a man—are actions generated by the organism itself and directed to a single goal: the maintenance of the organism’s life.
When applied to physical phenomena, such as the automatic functions of an organism, the term “goal-directed” is not to be taken to mean “purposive” (a concept applicable only to the actions of a consciousness) and is not to imply the existence of any teleological principle operating in insentient nature. I use the term “goal-directed,” in this context, to designate the fact that the automatic functions of living organisms are actions whose nature is such that they result in the preservation of an organism’s life.