The labours of physicists like Mach, Duhem, and Ostwald, point to alternative formulations of new hypotheses for the best established laws.  The physics of Newton are no longer final, and the notion of ‘energy’ is a dangerous rival to the older conception of ‘matter.’  It is, of course, indifferent to the philosopher whether the new physics are successful in superseding the old or not.  What it concerns him to note is that dogmatic confidence in the finality of scientific laws has given place to a belief that our “laws” are only working formulae for scientific purposes, and that no science can truly boast of having read off the mind of the Deity.  As Sir J.J.  Thomson neatly puts it, a scientific theory, for the enlightened modern scientist, is a ‘policy and not a creed.’  Science has become content to be only ‘a conceptual shorthand,’ provided that its message be humanly intelligible.  It no longer claims truth because abstractly and absolutely it ‘corresponds with Nature,’ but because it yields a convenient means of mastering the flux of events.

Even mathematics, long the pattern of absolute knowledge, has not escaped the stigma of relativity.  ‘Metageometries’ have been invented by Riemann and Lobatschewski as rivals to the assumptions of Euclid, and the brilliant writings of Poincare have explained the human devices on which mathematical concepts rest.  Euclidean geometry is reduced to a useful interpretation of the data of experience; it is not theoretically the only one.  Its superior validity is dependent upon its use when applied to the physical world.  Even mathematics, therefore, lend themselves to the philosophic inference drawn by Henri Bergson and others, that all conceptual systems of the human mind have a merely conditional truth, depending on the circumstances of their application.

2.  Another fountain-head of Pragmatic philosophy has been Darwinism.  Indeed, the Pragmatic is the only philosophizing which has completely assimilated Evolution.  The insight into the real fluidity of natural species ought long ago to have toned down the artificial rigidity of logical classifications.  To know reality man can no longer rest in a ‘timeless’ contemplation of a static system; he must expand his thoughts so as to cope with a perpetually changing process.  Since the world changes, his ‘truths’ must change to fit it.  He is faced with the necessity of a continuous reconstruction of beliefs.  This influence of Darwin has inspired the logical theories of Professor Dewey and the ‘Chicago School’ of Pragmatists.  Thought in their writings is essentially the instrument of this readjustment.  Its function is to effect the necessary changes in beliefs as economically and usefully as possible.  It is an evolving process which keeps pace with the evolution of reality and the changing situations of mortal life.