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Hertz (eliminates “force”): *
Principles of Mechanics (1894) was a rewriting of classical mechanics, an alternative explanation. Hertz wanted to reduce assumptions while maintaining the empirical & non-metaphysical aspect. He admits the value of logical categories & metaphysical statements but argues the scientist must distinguish between the different categories & not mistake the empirical with the non-empirical. Scientists need to clearly understand the logic of the concepts. While the laws of mechanics are fundamental in the solving of problems in physics, many are by no means clear. The outstanding example of this confusion is "force."; Hertz is critical of physicists for using this concept without understanding what it entails. Most textbooks take space, time, force & mass as fundamental concepts, reflecting historical development but not logical structure. It takes force as an independent concept, the cause of motion, yet the idea of force is not clear & associated with non-essential anthropomorphic ideas, thereby importing superfluous elements. Too much of the imperceptible is brought into mechanics.
In classical mechanics, force is not used in the way physicists think; the normal manner of expounding mechanics obscures the nature of force. Understanding the concept is inextricably bound up with understanding the theory. Mechanics explains the motions of bodies by bringing them under laws, but these cannot be limited to the directly observable. Force & energy are non-empirical concepts. Many explanations rely upon concealed mechanisms, which Hertz calls “'confederates” hidden beyond observed masses and motions. Hertz argues the best explanations are those using concepts paralleling our experience (empirical) .
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In his Principles of Mechanics Hertz replaces force & energy them with motion & mass, which behave exactly like observed motion & mass except that they are unobserved (concealed). . He points to Maxwell’s account of electromagnetic forces in terms of concealed masses and motions He gives force & energy minor roles in his mechanics; the important roles go to mass and motion. Hertz attempts to do without force & energy, instead deriving the whole of mechanics from space, time & mass, force & energy used only as devices for calculation. These 3 are primitive terms but not mere abstractions, rather understood through experience & these are permanently related in various ways.
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Newton (quote: " hypotheses non fingo,"): *
The quote in full:
I have not as yet been able to discover the reason for these properties of gravity from phenomena, and I do not feign hypotheses. For whatever is not deduced from the phenomena must be called a hypothesis; and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferred from the phenomena, and afterwards rendered general by induction.