Law and Nature

Laws and Nature

When Newton brought all motion under a single set of laws, he changed our view of nature. Now nature was uniform, seamless, of a piece. These laws were mathematical, so nature was mathematical. The natural kind corresponding to these laws was a mathematical kind. Mass, force, and velocity were mathematical kinds, definable mathematically. But then, all moving objects had the same general real essence—masses in mathematical motion. Differences of natural kind were negligible in the light on the universal laws of motion. Nature is defined by its laws and these laws were uniform. Planets, rocks, animals, humans—all were subject to the same physical laws, mathematically formulated. All should then be covered by the same science. A certain image of physical reality was conjured by this Newtonian vision: abstract, mechanical, invariant, homogeneous, mathematical. It was an entrancing vision, laying out a format for all natural sciences. It should apply to everything that moves, including animals and people.

But the science of biology was different: organisms move differently from each other, and they differ strikingly in other ways too. The biological taxonomists had their work cut out for them. Newton was no help to them. They focused on species and their differences: how did these species originate, and what defined them? The differences were at least as important as the similarities. Darwin did not seek universal laws of animal motion, applicable to Earth and beyond; he had other fish to fry (or describe). Newton’s problems were not his. He was not blinded by mathematical science, oblivious to form and function, concentrating only on mass. This made biology into a different kind of science; more different even than psychology, which could focus on the universal laws of stimulus and response. Biology, especially zoology, was all about diversity, not uniformity. It dealt with the problem of diverse species, while Newtonian physics was about uniform matter. For physics all matter belongs to one natural kind; for biology life forms are of different natural kinds. The laws, such as they are, vary from species to species; very little unites them. The natural kind ANIMAL plays a negligible role and is hard to define. The natural kind LIVING THING is even harder to pin down and is probably not even a natural kind. There are no uniform biological laws of motion—ways that all creatures behave (move through space). In physics general laws lead to mathematical etiolation, but in biology we have concrete individuality of kinds. Newton’s vision (inherited by modern physics) is one of vast homogeneity, while Darwin’s vision is one of limitless variety, local specificity. What we call “nature” looks very different under each dispensation.[1]

[1] This paper belongs with my “Biology and Physics”.