¹ For a recent discussion of the steady state, with special reference to biological conditions, cf. the recent paper of Alan C. Burton, “The Properties of the Steady State Compared to Those of Equilibrium. ...” Journal of Cellular and Comparative Physiology, 1939, vol. 14, p. 327.

² Cf. e.g. the recent book of K. Goldstein, “The Organism,” New York, American Book Co., 1939.

³ It should be noted, however, in considering the totality of the conditions determining an event, that part of these conditions are not environmental but are internal to the event itself. Also in their very nature these may not all be open to external observation. This is a fact of special importance in biological causation (see below).

3a A requirement emphasized by Hume. Cf. the recent article in this Journal by R. B. Winn, “The Nature of Causation,” vol. 7, 1940, p. 192.

⁴ This is the condition which Newton perceived clearly in his requirement of a medium for gravitational action.

4a This phrase, “causal structure,” is also used by H. J. Jordan, Acta Biotheoretica, 1935. vol. 1, p. 100.

4b Note that underlying the atomic stability are other kinds of stability, e.g., electronic charge, quantions constant, and so on.

⁵ The word is etymologically equivalent to non-divisibility, or non-disintegrability, corresponding to a certain kind of stability. Note also the psychological analogy of selfhood (psychic isolation). Obviously there is a great gap between the individuality of an atom and that of a human being, but both types illustrate, in their close combination or interfusion of active and static (= structural or formal) characters, as well as in their isolation, the same general principle of natural individuation.

⁶ Or “continuant.” Cf. R. W. Sellars, “The Philosophy of Physical Realism,” pp. 301 ff.

⁷ Cf. (e.g.) Lindsay and Margenau, “Foundations of Physics,” New York, 1936, p. 351. E is total energy, m stationary mass, c velocity of light. In a moving body E = mc² + 1/2 mv², where v is the velocity of motion of the body. A simple calculation shows that for a gram mass moving at high projectile velocity, one kilometer per second, the ratio of the intrinsic energy to the ordinary kinetic energy would be 18¹⁰ to 1.

⁸ Compare the remarks of Niels Bohr, “Causality and Complementarity,” Philosophy of Science, 1937, vol. 4, p. 289; cf. p. 295.

8a Similarly temporal successions of auditory sensa are combined to form words, sentences, rhythms, melodies, etc.

⁹ Henri Bergson, Creative Evolution, New York, 1911.

¹⁰ This reservation is made to allow for habit; synthetic procedures, once discovered, may become unconscious (or “mechanized”) by repetition.

¹¹ For a fuller discussion of directive action cf. my recent paper, “Directive Action and Life,” Philosophy of Science, 1937, vol, 4, p. 202.

¹² This would imply in physical analysis that the internal or intrinsic atomic energy is in some way applied to determine the time, place, and direction in which quanta of action are transferred.

¹³ I say “in part,” because any natural system of observables is found, when analyzed closely, to taper off into unobservables,—i.e., physically speaking, into systems consisting of atomic units which become observable only when they transfer a portion of their own (or reflected) energy to other complexes of atomic units, viz., those forming part of the observer's organism. The preponderance of atomic energy remains (in this sense) un-observable. To suppose that physical unobservables cannot act as determinants in special events is like supposing that the externally unobservable factors in another human being (his psychic life, volition, etc.) have no determining effect on his behavior—which seems an unrealistic assumption!

¹⁴ As will be indicated more fully below, each type of individuation has its own special types of causation; to give a biological illustration, hormonal causation has reached a high state of development in vertebrates, but apparently not in insects.

¹⁵ A. N. Whitehead, “Process and Reality,” passim.

¹⁶ I.e. the concepts “purely mental” and “purely physical” are abstractional fictions. Cf. H. Prinzhorn, “Psychotherapy,” London, J. Cape, 1932, p. 97, for a fuller discussion.

¹⁷ The distinction between chemical “statics” and “dynamics” is familiar, referring respectively to conditions of equilibrium and conditions of chemical change. (Cf. such a work as Mellor's “Chemical Statics and Dynamics.”)

¹⁸ I refer here particularly to the fact that each cycle of development, as exhibited in different species of animal and plant, has its constant and specific characters. This problem is discussed at some length in my recent address, “The Nature of Organizing Action,” Amer. Naturalist, 1938, vol. 72, p. 389.

18a Apparently Eddington believes this and similar relations are mathematically deducible (cf. his recent Tarner Lectures, “The Philosophy of Physical Science,” Cambridge University Press, 1939), but Einstein expresses himself with reservations (Address before the Eighth American Scientific Congress, Washington, May 15, 1940, printed in Science, 1940, vol. 91, p. 487).

¹⁹ The hypothesis of an all-pervading uniform medium or ether has lately been discredited as unnecessary by many physicists, under the influence of relativity theory; but the question as to its physical existence or non-existence would seem after all to be a matter of experimental evidence. As a naturalist, I do not quite see how we can dispense with an ether, if by the term we mean some homogeneous neutral background, matrix or container which provides the static conditions for the observed regularity of physical action occurring within it. Such a concept corresponds closely with the Newtonian concept of “empty” space. Of course the question of how its geometrical characters are best represented is one for the mathematical physicists to decide. But the fact that valid calculations can be made, without considering at the time the physical nature of the conditions assumed as constant in the calculation, need not mean that these conditions have in themselves nothing corresponding to physical existence. Facts like the stable setting of the stars and nebulæ, experiments like the Foucault pendulum and others, were formerly thought to indicate the existence everywhere of a uniform medium with fixed coordinates. Opinions differ as to the theoretical significance of the Michelson-Morley experiment—and even (it seems) as to the facts. Recently the question of the physical existence of an ether has been raised again, on purely physical grounds, by H. E. Ives, in an address recently published in Science (1940, vol. 91, p. 79), “The Measurement of Velocity with Atomic Clocks.”

²⁰ This has been emphasized especially by L. J. Henderson, “The Order of Nature,” Harvard University Press, 1917.

²¹ A. N. Whitehead: “Process and Reality,” passim.