Are living organisms--as Descartes argued--just machines? Or is the nature of life such that it can never be fully explained by mechanistic models? In this thought-provoking and controversial book, eminent geophysicist Walter M. Elsasser argues that the behavior of living organisms cannot be reduced to physico-chemical causality. Suggesting that molecular biology today is at the same point as Newtonian physics on the eve of the quantum revolution, Elsasser lays the foundation for a theoretical biology that points the way toward a (...) natural philosophy of organic life. Explicitly repudiating "vitalism" (the notion that the laws of nature need to be modified when applied to living organisms), Elsasser argues instead that the structural complexity of even a single living cell is "transcomputational"--that is, beyond the power of any imaginable system to compute. Beginning from this insight, Elsasser leads the reader through a step-by-step process that ultimately arrives at the conclusion that living and non-living matter are separated by "a no-man's land of irrationality." Trained in Germany as a physicist, Elsasser first pondered the implications of quantum mechanics for biology as early as 1951. The more closely he studied the inherent complexity of life, the more skeptical he became of the reductionist view of organisms as tiny machines. "An organism," he concluded, "is a source of causal chains which cannot be traced beyond a terminal point because they are lost in the unfathomable complexity of the organism." Like the physicist who works within the bounds of an unfathomable universe, Elsasser argues, the biologist must seek answers within a system that is no less unfathomable. (shrink)

"The time-honored dualism of the mutually exclusive systems of thought, mechanistic biology on the one hand and vitalism on the other, expresses a pair of theoretical approaches which are both inadequate. We shall show how they can be replaced by an abstractly descriptive system of a different type that is far better adapted to the nature of biology"--Preface.

A quarter of a century has elapsed since quantum mechanics was discovered. Perhaps it is not too much to say, in retrospect, that the time was ripe for this particular development. This is attested, not only by the speed with which the edifice of the theory was completed immediately following the basic discoveries of Heisenberg and Schrödinger, but also by the rapidity, well-nigh unprecedented in the history of science with which the new results were applied to almost every branch of (...) physics and chemistry. A mental readiness on the part of the scientists involved might have had much more to do with this than the facilities of modern communication systems. (shrink)

A systematic effort is here made to express some of the general results of quantum mechanics in a conceptual form closer to ordinary language than is the case with most modern physics. Many of the implications of the theory appear much more clearly thereby, in particular the fact that the laws of quantum mechanics are only statistical propositions about classes, not referring to individual objects. Conversely, the microscopic structure of an object cannot be precisely defined in quantum mechanical terms. To (...) say that an object has a definite microscopic structure is an operationally meaningless statement; it is on the same level as saying in relativity that a selected coordinate system is “at rest.” This raises the need for a “theory of matching”: What is the best statement about the structure of an object, given that the tools of description are only statistical? A technique is known for this: the theory of inductive probabilities. There is no longer one true description but a manifold of statistical descriptions, some of which have a greater likelihood of being satisfactory than others. The main concrete application of this type of conceptual reasoning lies in its power to clean out the speculative underbrush which so far has prevented the transition from theoretical physics to theoretical biology. (shrink)

The book of Bergson underlying the present study appeared in 1896. It is entitled “Matter and Memory” and is a philosophical disquisition into the relation and mutual limitations of organic life and inert matter. Bergson proposes to deal with this very general problem under the special aspect of a theory of the functioning of the human brain and the mechanism of ordinary memory. Such use of the inductive method, which starts from a special problem in order to arrive at results (...) that might be generalized later, might endear him to the exact scientist who has a healthy skepticism toward pure generalities. But let us for a moment remain in the realm of generalities in order to better circumscribe the subject: Few people would agree to an entirely mechanistic interpretation of organic life; hence there should be some point in biology at which the deviations from pure mechanism appear explicitly and in their fulness. For the present we shall adopt an intentionally oversimplified mode of expression. Let us say that mechanistic description is causal and that as our analysis progresses we must eventually arrive at a point where we can no longer trace the causal chains in their entirety. At that point we must replace causal “classical” physics by quantum mechanics and form our pictures of microscopic realities of organic matter in terms of the latter. Some of the pertinent problems have been pointed out by the present writer among others, following earlier suggestions by Niels Bohr. Suffice it here to say that certain processes of the atomic scale going on in a complex system such as the organic tissue essentially escape detailed observation that would allow us to determine the continuity of an entirely causal nexus. It is possible to make such observations, but they result in physical destruction of the very coherence of the organic tissue upon which the biological functioning depends. Bohr describes this condition by the term “generalized complementarity.” We cannot enter into a discussion of these problems here; let us adopt deliberately the oversimplified and somewhat vague expression that at some point indeterminacies become significant in the microscopic processes that take place in the organic body. We shall try to limit ourselves in this paper to the simplistic notion of a multiplicity of indeterminate events inserted into the play of molecular reactions that constitute the functioning of the organism from the viewpoint of the physicist and chemist. (shrink)