A beginning of the end of the holism versus reductionism debate?: Molecular biology goes cellular and organismic

A bout 20 years ago the famous biologist and scholar of evolutionary game theory, John Maynard Smith commented on the holism versus reductionism debate between organismic and molecular biologists with the following phrase [1]: “... Holists are, I think, in a weaker position, if only because progress has been so much faster from the bottom up than from the top down. Yet, I do share their conviction that there are laws that can only be discovered by research on whole organisms, and on populations of organisms. Almost all my own work has been done at those levels. What should be the attitude of a biologist working on whole organisms to molecular biology? It is, I think foolish to argue that we are discovering things that disprove molecular biology. It would be sensible to say that there are phenomena that they will one day have to interpret in their terms. ...”. As I shall try to outline later in this essay the expectations of John Maynard Smith have today become (almost) true in the emerging field of systems biology. The holism versus reductionism debate is an old theme in philosophy and science. Sometimes holism is even traced back to Aristotle’s “Metaphysics,” which contains the famous sentence: “The whole is more than the sum of its parts.” The problem here is the usage of the term “sum.” If sum implies a simple arithmetic sum, the statement expresses nothing more and nothing less that the parts of the whole do interact. For every property F( ) of an ensemble {X1,X2, ..., Xn} we can write