That is where I part company with Professor James Ward in the second volume of Naturalism and Agnosticism; with whom nevertheless on many broad issues I find myself in fair agreement. Those who find a real antinomy between "mechanism and morals" must either throw overboard the possibility of interference or guidance or willed action altogether, which is one alternative, or must assume that the laws of Physics are only approximate and untrustworthy, which is the other alternative—the alternative apparently favoured by Professor James Ward. I wish to argue that neither of these alternatives is necessary, and that there is a third or middle course of proverbial safety: all that is necessary is to realise and admit that the laws of Physical Science are incomplete, when regarded as a formulation and philosophical summary of the universe in general. No Laplacian calculator can be supplied with all the data.
On a stagnant and inactive world life would admittedly be powerless: it could only make dry bones stir in such a world if itself were a form of energy; I do not suppose for a moment that it could be incarnated on such a world; it is only potent where inorganic energy is mechanically "available"—to use Lord Kelvin's term,—that is to say, is either potentially or actually in process of transfer and transformation. In other words, life can generate no trace of energy, it can only guide its transmutations.
It has gradually dawned upon me that the reason why Philosophers who are well acquainted with Physical or Dynamical Science are apt to fall into the error of supposing that mental and vital interference with the material world is impossible, in spite of their clamorous experience to the contrary (or else, on the strength of that experience, to conceive that there is something the matter with the formulation of physical and dynamical laws), is because all such interference is naturally and necessarily excluded from scientific methods and treatises.
In pure Mechanics, "force" is treated as a function of configuration and momentum: the positions, the velocities, and the accelerations of a conservative system depend solely on each other, on initial conditions, and on mass; or, if we choose so to express it, the co-ordinates, the momenta, and the kinetic energies, of the parts of any dynamical system whatever, are all functions of time and of each other, and of nothing else. In other words, we have to deal, in this mode of regarding things, with a definite and completely determinate world, to which prediction may confidently be applied.
But this determinateness is got by refusing to contemplate anything outside a certain scheme: it is an internal truth within the assigned boundaries, and is quite consistent with psychical interference and indeterminateness, as soon as those boundaries are ignored; determinateness is not part of the essence of dynamical doctrine, it is arrived at by the tacit assumption that no undynamical or hyperdynamical agencies exist: in short, by that process of abstraction which is invariably necessary for simplicity, and indeed for possibility, of methodical human treatment. Everyone engaged in scientific research is aware that if exuberant charwomen, or intelligent but mischievous students (who for the moment may be taken to represent life and mind respectively) are admitted into a laboratory and given full scope for their activities, the subsequent scientific results—though still, no doubt, in some strained sense, concordant with law and order—are apt to be too complicated for investigation; wherefore there is usually an endeavour to exclude these incalculable influences, and to make a tacit assumption that they have not been let in.
There is a similar tacit assumption in treatises on Physics and Chemistry; viz., that the laws of automatic nature shall be allowed unrestricted and unaided play, that nothing shall intervene in any operation from start to finish save mechanical sequent and antecedent,—that it is permissible in fact to exercise abstraction, as usual, to the exclusion of agents not necessarily connected with the problem, and not contemplated by the equations.
In text-books of Dynamics and in treatises of Natural Philosophy that is a perfectly legitimate procedure;[4 ] but when later on we come to philosophise, and to deal with the universe as a whole, we must forgo the ingrained habit of abstraction, and must remember that for a complete treatment nothing must permanently be ignored. So if life and mind and will, and curiosity and mischief and folly, and greed and fraud and malice, and a whole catalogue of attributes and things not contemplated in Natural Philosophy—if these are known to have any real existence in the larger world of total experience, and if there is any reason to believe that any one of them may have had some influence in determining an observed result, then it is foolish to exclude these things from philosophic consideration, on the ground that they are out of place in the realm of Natural Philosophy, that they are not allowed for in its scheme, and therefore cannot possibly be supposed capable of exerting any effective interference, any real guidance or control.
My contention then is—and in this contention I am practically speaking for my brother physicists—that whereas life or mind can neither generate energy nor directly exert force, yet it can cause matter to exert force on matter, and so can exercise guidance and control: it can so prepare any scene of activity, by arranging the position of existing material, and timing the liberation of existing energy, as to produce results concordant with an idea or scheme or intention: it can, in short, "aim" and "fire."
Guidance of matter can be affected by a passive exertion of force without doing work; as a quiescent rail can guide a train to its destination, provided an active engine propels it. But the analogy of the rail must not be pressed: the rail "guides" by exerting force perpendicular to the direction of motion, it does no work but it sustains an equal opposite reaction.[5 ] The guidance exercised by life or mind is managed in an unknown but certainly different fashion: "determination" can sustain no reaction—if it could it would be a straightforward mechanical agent—but it can utilise the mechanical properties both of rail and of engine; it arranged for the rail to be placed in position so that the lateral force thereby exerted should guide all future trains to a desired destination, and it further took steps to design and compose locomotives of sufficient power, and to start them at a prearranged time. It "employs" mechanical stress, as a capitalist employs a labourer, not doing anything itself, but directing the operations. It is impossible to explain all this fully by the laws of mechanics alone, that is to say, no mechanical analysis can be complete and all-embracing, though the whole procedure is fully subject to those laws.
To every force there is an equal opposite force or reaction, and a reaction may be against a live body, but it is never suspected of being against the abstraction life or mind—that would indeed be enlarging the scope of mechanics!—the reaction is always against some other body. All stresses as a matter of fact occur in the ether; and they all have a material terminus at each end (or in exceptional cases a wave-front or some other recondite ethereal equivalent), that is to say something possessing inertia; but the timed or opportune existence of a particular stress may be the result of organisation and control. Mechanical operations can be thus dominated by intelligence and purpose. When a stone is rolling over a cliff, it is all the same to "energy" whether it fall on point A or point B of the beach. But at A it shall merely dent the sand, whereas at B it shall strike a detonator and explode a mine. Scribbling on a piece of paper results in a certain distribution of fluid and production of a modicum of heat: so far as energy is concerned it is the same whether we sign Andrew Carnegie or Alexander Coppersmith, yet the one effort may land us in twelve months' imprisonment or may build a library, according to circumstances, while the other achieves no result at all. John Stuart Mill used to say that our sole power over Nature was to move things; but strictly speaking we cannot do even that: we can only arrange that things shall move each other, and can determine by suitably preconceived plans the kind and direction of the motion that shall ensue at a given time and place. Provided always that we include in this category of "things" our undoubtedly material bodies, muscles and nerves.