Human action, we have seen, arises from purposes formulated by the volitional consciousness of the individual. Because their actions are rooted in volition rather than inborn instincts, humans can adapt to an exceptionally wide range of environments and situations. On the other hand, because volitional consciousness is inherently fallible, an individual's specific actions can sometimes conflict with the overall goal of such action—namely, maintaining and promoting that individual's life.

Fallibility is not an issue for plants and other animals that act automatically and instinctively to fulfill their life-needs. For the most part, such action is determined by evolution and natural selection, so that the organism is driven automatically to fulfill its objective needs. In exceptional cases, such instincts may fail because the organism's environment has changed too rapidly for evolution to keep pace; for instance, a dog may tend to overeat when exposed to a food supply much more copious than that which its ancestors' environment provided. Even in such instances, however, fallibility is not really an issue for the dog, which does not choose its behavior and cannot conceptualize alternatives.