ABSTRACT
The developmental transformation from animal to human existence entails a radical change in the nature of the transactions between the organism and its milieus: human beings are not merely, nor mainly, organisms reacting to stimuli or responding to things-of-action. Man forms his Umwelt by relating to his environments in a new manner: lie is directed toward knowing. The orientation toward, and the capacity for, knowing are essential and irreducible characteristics of man, characteristics that come clearly into relief when one compares the nature of the adaptiveness of animals and men to their respective environments. In animals—particularly in lower animals—organism and environment are closely attuned to each other; one might say-that both are elements in a comparatively closed system, within which stimulation and response are tightly interlocked. With ascendence on the evolutionary scale, the closed system begins to open up: the relative rigidity of adaptive responses, the species-specific conformity to environments, gives way increasingly to choice responses, to modifiability and plasticity of behavior, and to an increasing trend toward learning through individual experience.
