Autor: Melchin, R. Kenneth

Buch: History, Ethics and Emegent Probability

Titel: History, Ethics and Emegent Probability

Stichwort: Verhältnis zw. Biologie und Chemie / Physik am Beispiel d. Amöbe (Rashevski);

Kurzinhalt: Rashevski's attempts to discern common patterns at the molecular level among groups of amoeba cells yields only explanations of individual cells as particular and unique.

Textausschnitt: 11/4 In his ninth chapter of Randomness, Statistics and Emergence, McShane draws upon some evidence gained from experiments performed by N. Rashevski in the field of mathematical biophysics to point towards the significance of randomness in relating scientific explanatory 'levels.'1 The relations between the processes of biology and the laws of physics and chemistry can be illustrated in contemporary accounts of the life processes of the amoeba. The amoeba consists of atoms and molecules within a certain spatio-temporal range and distribution. But the biological accounts of amoeba-processes, such as digestion, excretion and reproduction, while rooted in physical and chemical explanations, concern a system of characteristics and relations that supervene upon the physical and chemical phenomena. If these biological processes ultimately can be explained completely in terms of the physical and chemical laws then what is the status of the distinct terms and relations of biology? How are we to understand the relation between biological laws and physico-chemical laws? (103; Fs)

12/4 One approach to the problem among philosophers of science has anticipated a systematic or functional relationship between the physical and chemical conditions associated with an amoeba and the biological processes of that amoeba.2 That is to say the philosophers anticipate a unified set of functional relationships which grasp and express a single pattern of interactions among all of the relevant physical and chemical processes associated with every amoeba. And this unified pattern, expressed in the terms of physics and chemistry, would decisively account for all the biological functions which distinguish each amoeba as an instance of the generalized class, amoeba. The particularities of each individual amoeba, in this physico-chemical explanation, would be irrelevant to understanding each amoeba as an amoeba.3 But McShane notes that this anticipation leads to a dilemma. Since biological explanations concern a completely different set of terms and relations from those of physics and chemistry, the philosopher of science is forced either to conclude that the higher, biological level, distinguished by non-deducible characteristics is an epiphenomenon (Pepper) or to accept the overwhelming power of the biological explanations and to account for them by introducing non-scientific factors that could neither be measured nor verified (Meehl and Sellars).4 (103f; Fs)

13/4 McShane approaches this dilemma by noting that the working hypothesis among serious biologists is of distinct levels of science; levels that concern different sets of terms and relations.5 He notes, too, that evidence from the work of such scholars as H. Kaeser,6 and N. Rashevski leads one to conclude that this hypothesis of systematic or functional relationships is not empirically tenable.7 Rashevski's attempts to discern common patterns at the molecular level among groups of amoeba cells yields only explanations of individual cells as particular and unique. (104; Fs)

But, since there are no two cells perfectly alike, the exact solution of the problem for a given case would contain a tremendous amount of detail which is biologically insignificant because it applies only to the given case.8
Similarly H. Kaeser remarks that: (104; Fs)

[...] the complete enumeration, even if it were possible, of all the molecules within an organism would not account for any but its most trivial aspects.9
McShane finds that the evidence points to the fact of randomness, in some way or another, operative at the physical and chemical levels. (104; Fs)

[...] the processes involved within the amoeba form a coincidental aggregate which can be understood concretely only through a coincidental aggregate of equations and conditions.10

When amoeba processes are explained in terms of physics and chemistry it would seem from the evidence that it is the pattern that is particular and unique to the processes of each amoeba that decisively interrelates what is common to all amoebas. If there exists a single set of generalized explanations of the biological processes operative in all amoebas it cannot consist of classical explanations of biological processes as outcomes of determining physical and chemical conditions.11

14/4 McShane takes the evidence of randomness or absence of system as a clue to the relevance of a statistical element in explaining the relationship between 'levels' of explanation. In terms of the definition of f-probability developed in the previous chapter, a statistical norm or an f-probability neither precludes the determinate operation of classical laws nor explains classes of outcomes in terms of determining conditions. Rather, in a random or non-systematic process a converging coincidence of laws whose pattern or intelligibility may be unique in any single occurrence of the process, nonetheless can yield an event or an outcome that can be classified in a direct insight. This outcome is recognized as an instance of a class of events which recurs and which, together with other types of events, defines a population. The event recurs not because of an identical pattern or intelligibility in a set of classical laws. Rather, because a set of initiating and boundary conditions forces a randomly interacting set of classical processes to yield one or another from a determinate set of classifiable outcomes, the classes of outcomes recur with a more or less stable frequency that is expressed in an f-probability, and this f-probability can be explained in terms of a few initiating, environmental or boundary conditions without violating the absence of system relating the conditions to outcomes. (104f; Fs)

15/4 Thus a succession of events of one particular class can recur without any common systematic or intelligible explanation in terms of determining conditions but with a relatively stable frequency that is explained in part in terms of a few selected conditions and in part in terms of the other events that make up the population.12 The introduction of Lonergan's notion of f-probability makes at least possible or conceivable an explanation of f-probably recurring classes of events in terms other than a complete functional or systematic correlation between events and conditions. Whether this clue can constitute an element in an adequate explanation of the relation between explanatory levels in science depends upon whether f-probably recurring events can link up with other f-probably recurring events to yield new systematic patterns and 'laws.' And Lonergan's notion of the 'recurrence scheme' is an attempt to conceive this possibility. (105; Fs)