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Entailment, causality, and "why?" questions



It seems to me that any discussion about my father's work must include certain key concepts that pervade the whole. One of those is the concept of entailment.
 
In the Praeludium of "Life, Itself", on page 10:
 
Robert Rosen wrote: "It seems to me that the duality between "hard" or quantitative science and "soft" or qualitative science rests on an entirely false presumption. It is not a question of doing physics or not doing science at all. It is rather a relative question, of simplicity versus complexity.
 
I would in particular draw attention to the way [these] ideas rest on entailment alone, on systems of entailment in the material world (causal entailment) and in the world of formalisms or mathematics (inferential entailment), and on comparisons or congruences between such entailment systems. I have come to believe that the concept of entailment provides a reliable anchorage for the scientific enterprise itself, and I accordingly recommend it to your attention."
 
On page 13:
 
Robert Rosen wrote (about tying to ascertain the answer to the question "Why are living things alive?"...): The muteness of physics arises from its fundamental inapplicability to biology and betokens the most profound changes in physics itself...
 
In any event, the task that physics has shirked devolves next onto biologists, perhaps properly so, since it is central to their every enterprise. What light then, do biologists shed on the taproot of their own endeavors? In fact, precious little. Indeed, a rather strange and dreary consensus has emerged in biology over the past three or four decades. On the one hand, biologists have convinced themselves that the processes of life do not violate any known physical principles; thus they call themselves "mechanists" rather than "vitalists". Further, biologists believe that life is somehow the inevitable necessary consequence of underlying physical (inanimate) processes; this is one of the wellsprings of reductionism. But on the other hand, modern biologists are also, most fervently, evolutionists; they believe wholeheartedly that everything about organisms is shaped by essentially historical, accidental factors, which are inherently unpredictable and to which no universal principles can apply. That is, they believe that everything about life is not necessary but contingent. The unperceived ironies and contradictions in these beliefs are encapsulated in the recent boast by a molecular biologist: "molecular biologists do not believe in equations." What is relinquished so glibly here is nothing less than any shred of logical necessity in biology, and with it, any capacity to actually understand. In place of understanding, we are allowed only standing-- and watching. Thus, if the physicist stands mute, the biologist actually negates, while pretending not to.
 
Thus, to ask the question "What is life?" is to find oneself standing essentially alone. But perhaps not entirely; there is yet another oracle to be consulted. That oracle is System Theory, which as yet speaks only in whispers. Insofar as it can be characterized, System Theory is the study of organization per se, divorced from material embodiment, as the form of a statue can be divorced from the marble or as cardinality can be divorced from the things being enumerated. This oracle will at least entertain the question but only when it has been transmuted to a new form: not what is special about life in terms of matter but what is special about it in terms of organization. This is good, because obviously organisms are, in purely material terms, of the greatest diversity. But it is not, by itself, good enough. Moreover, this oracle speaks not of laws or principles, as physics does; as yet it can speak only in parables.
 
Thus the question remains, and it is the THE question: What is life? It commands us to grapple with it and even allows us the luxury of choosing our own weapons for the struggle. But our armory is inadequate; wherever we look, some essential element is missing. Life is material, but the laws framed to describe the properties of matter give no purchase on life. Something is missing here, perhaps something essential for the understanding of matter in general, however much the physicists insist not. Biology has so far spent itself in cataloguing the endlessly interesting epiphenomena of life, but at the heart of it there is still only a gaping void. And the parables of the system theorist cannot as yet be incarnated in material reality. As I said, something is missing, something big, but it is hard to see even the biggest things when they are not there. We can only sense the void of its absence and try to fabricate what is necessary  to fill it.
 
That is what the present book is about. It is about the creation and the application of an armory for a renewed assault on the question of questions: What is life? In the process, we shall find ourselves partly in the world of physics, constructing a language appropriate for a physics of "organized matter", a physics of complex systems. We shall also find ourselves partly in the world of the system theorist, developing a language appropriate to "material organization" and thereby clothing that world in a substance and coherence it has largely lacked. We will be in the world of the mathematician, in the world of formalisms and formalizations. And finally, of course, we will find ourselves in the world of biology, to see how far our armamentarium will take us in our struggle with the question: What is life?
 
As a first step in our assault on the problem What is life? it will be well to get some idea of what we are up against. Specifically, we will try to understand what it is about the problem that has rendered it so refractory to the combined resources of our contemporary scientific wisdom. This will provide one way of sensing the shape of the void we need to fill and at the same time will help set the stage for our further, more technical developments, though we will not be able to reach a true answer to this question until we come to the end.
 
Let us begin by noting the very form of this question; we are asking WHY. We shall find ourselves asking "why" very often as we proceed. The answer to such a question (and indeed there are in general many ways to answer such a question) is to assert a "because". As we shall see abundantly later, to ask why is to enter the realm of causality, and to propose an answer is to posit something, to make a hypothesis. Although every physicist must believe in causality, this attitude towards positing a "because" was set long ago by Newton, whose proudest assertion was "hypothesis non fingo". Indeed, as we shall see, causality in contemporary physics has evolved into a very different kind of thing than that originally envisaged by Aristotle, a thing geared essentially to deal with the question "what?: and to provide answers of the form "this".
 
One of the main reasons the fundamental question "what is life?" is so hard will turn out to be closely associated with such ideas. It will turn out that this question is really a "why" question in disguise, that we are really asking, in physical terms, why a specific material system is an organism, and not something else. Such questions are not congenial to contemporary science. "