Carl Friedrich von Weizsacker describes himself as "a politically active professor of philosophy who was trained as a physicist." He is also, with his old mentor Werner Heisenberg, one of the two most interesting and complex alumni of the World War II German atomic bomb project.
This second fact is not bragged about on dust jackets, but it is worth mentioning, I think, even in connection with "The Unity of Nature." In this book of essays on physics and philosophy von Weizsacker concerns himself with the quest for a unification of scientific and philosophical vision -- or the reconciliation of things apparently unrelated. And yet the two Carl Friedrich von Weizsackers -- august and humane philosopher in 1980, brilliant young Hitlerian Vulcan in 1940 -- remain disconcertingly unreconciled. History must wait for a satisfactory account of precisely what role Heisenberg and von Weizsacker, these two personable geniuses, may have played in the effort to supply Hitler with an atomic weapon, and upon precisely what motivations.
That caveat stated, I want to add quickly that "The Unity of Nature" is a formidable, engaging, valuable, and monumentally learned book. It is so learned , in fact, and so polymathic, that unless you are a postgraduate physicist who has kept up on your quantum theory and found time along the way for careful study of Plato and Kant and Wittgenstein, large portions (but not all) of this book will serve you mainly as an exercise in humility. Robert Oppenheimer would have swallowed it like popcorn. The rest of us can stare at a panful of impenetrable kernels, and occasionally one will burst open brightly.
The essays included were written over 12 years, but they combine, says the author, "to exhibit a singlem philosophical idea, the idea of the unity of nature." That idea of unity, von Weizsacker admits, is not a granted premise, not an edifice of theory, but a programm -- in fact the ultimate program -- to be pursued by scientists and philosophers. It is exactly the program Einstein was pursuing as he labored through his last 30 years, trying unsuccessfully to develop a unified field theory that would explain the connection between electromagnetism and gravity. Heisenberg has endorsed the same program, working also toward a unified theory of physics, with tentative results somewhat more promising than Einstein's.
The task Von Weizsacker has set for himself is at once more modest and more broad. In these essays he proposes not new theories but ways of mutually reconciling a dizzying range of existent ones: quantum theory, information theory, theory of language, biological cybernetics, the Platonic theory of Forms. They must all, he urges, be made to elucidate each other. They must be made to intermesh.
"Science in the modern sense," von Weizsacker says, "is the collective achievement of a social group. The realization of the unity of nature, if scientifically feasible, can come about only as a result of this collective achievement. Therefore, so long as science remains incomplete, the idea of the unity of nature can be presented only in the form of a program illustrated by examples. In this conception, philosophy does not play the role of a fundamental science which formulates the principles for the specialized disciplines in a historically a priori sense; philosophy is indispensable, not to lay down the laws, but to continue asking the questions."
In "The Unity of Nature," those questions are asked by one of the most agile minds of the 20th century. Obscure as parts of it may be to the average reader, it is a book worth owning and puzzling over.