Whitehead's
philosophy is best seen as rooted in the British empirical tradition. In the
works (often regarded as his best) on the philosophy of nature, such as the
Principles of Natural Knowledge and Concept of Nature he developed
rigorously the notion of nature as nothing more than that which is observed
in perception through the senses. He attacked the "bifurcation of nature"
into apparent nature (the world of immediate experience characterized by colour,
sound, etc) and causal nature (the world as science supposedly tells us it
is, that is, the world of particles in motion which does not itself really
possess colour or sound but somehow gives rise to our perceptions of them).
For Whitehead, natural science had to be simply an account of the content
of perception, not a speculation about causes. Influenced by relativity theory,
he analysed that content as a four-dimensional structure of overlapping events;
he devoted much space and ingenuity to showing how concepts used in mathematics
and physics, those of point, line, instant, etc., which are not directly given
in experience, can be defined in terms of things which are, that is, simply
as certain sets of events, contained within each other "like nests of Chinese
boxes", and converging to a certain ideal simplicity of character.
The later works present an all-embracing view of reality in which, very roughly, each of its basic elements, each "actual entity", is essentially a process of self-development, or self-creation, by selection and rearrangement of the material provided by its background - on the completion of which it in its turn becomes material for the self-creations of the next generation of actual entities. The obvious analogy is with the life cycle of plants and other organisms - hence the title "philosophy of organism". With a characteristic effort of generalization, Whitehead here proposes to apply concepts which originate in the study of organisms to the interpretation of everything from physics to human psychology. How far he succeeds is, of course, open to question, but the over-all result is one of the most formidable attempts in the last century to characterize the concrete reality of the world, rather than the convenient abstractions of everyday discourse.
A Dictionary Of Philosophy. Second edition. (Pan Books 1984). Pages 373-374.