[waccREGOR] HYPOTHESES OF ABSTRACT DYNAMICS 95 
must be less probable than the results of the contact-action treatment. It 
is implied that the assumptions which the molecular theorists have em- 
ployed are the only ones consistent with that hypothesis. Accordingly 
Mr. Love sums up in favour of the contact theorists, saying that we must 
discard a subsidiary hypothesis about molecular force. He thus con- 
demns the molecular conception itself, not merely the particular assump- 
tions which have been employed in applying it. He also expresses ap- 
proval of the contact-action conception, on the ground that the laws of 
energy (the assumptions which have been employed in applying it) are 
“known,” and the deductions from it therefore “certainly true.” We 
cannot, however, assert that “the known laws of energy lead to results 
which are certainly true,” when applied by the aid of the contact-action 
conception. We must add: provided we are justified in using the 
contact-action conception. Were these laws applied by the aid of the 
molecular conception, without the employment of any additional assump- 
tion, we should have an equal right to assert that the results must be 
true, there being no criterion whereby we can judye of the relative merits 
of the contact action and the molecular conceptions, respectively. But 
obviously the results of both modes of discussion must be doubtful till we 
are sure of the applicability of one or the other or both, of the rival con- 
ceptions. 
It would, therefore, be of great interest to work out the theory of 
elasticity from the molecular point of view without making the additional 
assumption of the physical independence of stresses, assuming only the 
laws of the conservation and of the transformation of energy, or their 
logical equivalents, as specified above. If it were found impossible to 
elaborate the theory with these assumptions only, then the molecular 
conception would be shown to be inferior in utility to the contact-action 
conception. If it were found capable of elaboration, and to give results 
differing from the results obtained by the contact-action conception, then 
crucial experiments might decide which of the two conceptions is inap- 
plicable. But crucial experiments at present, should they decide in favour 
of the contact-action results, could show only that the molecular concep- 
tion, with the additional assumption, gives false results, and it would 
still be doubtful whether the error was due to the conception itself or to 
the additional assumption made in applying it. 
