From Physics to Biology

The aim of this paper is to investigate the foundations of the human and social sci­ences. Two interpretations of social reality, those of positivism and hermeneutics (born as a reaction to positivism), confronted each other.

I assume that physics is the prototype of the natural sciences and that sociology is the prototype of the social sciences. I shall seek to show not only their shared bases but also and especially their specificities. In doing so, I shall consider biology to be a science intermediate between physics and sociology, in that it possesses features that can be related to both the former and the latter. The transition from physics to biology will proceed upwards: at every step the specific nature of individual sciences will emerge. As a consequence, any type of reductionism will be avoided. Particular importance will be given to the concept of ‘reality’ in physics, biology and sociology. It will thus be seen how the ontology of the social (social being) can be introduced into the ontology of the external world (of physics and biology). In this regard, I shall show that the reality of physics and biology is independent of the observer (it is onto­logically objective) whilst the reality of sociology is dependent on the observer (it is epistemologically objective and normative). I shall examine the certain and uncontro- versial foundations of physics and biology, and on these foundations I shall base soci­ology as a science, of which I shall provide a preliminary epistemological analysis.

Alternatively, sociology can be founded independently of physics and biology, but this will not be the route followed here.

I begin by describing the essential features of physics at the origins of mod­ern science. The scientific revolution of the sixteenth and seventeenth centuries, whose protagonists were Galileo, Descartes and Newton, today represents the beginning of what we call ‘science’. At that time, science coincided with mechan­ics and astronomy. Galileo, in particular, was convinced that mechanics was the supreme science, the foundation and origin of all the sciences. Since mathemat­ics performs an essential role in mechanics, not surprisingly it was a decisive and essential component of Galileo’s conception of science. Famous in this regard is the definition that Galileo gave of ‘nature’ in The Assayer: “The book of nature cannot be understood unless one first understands the language and recognises the characters by which it is written. It is written in a mathematical language, and its characters are triangles, circles, and other geometric figures, without which means it is humanly impossible to understand a single word of it; without them it is like wandering hopelessly through a dark labyrinth”.

Galileo’s mechanics is a science formed by laws expressible in the language of mathematics. Mathematics is therefore its necessary and sufficient condition.

Physics (mechanics and astronomy) becomes the archetype, the model of sci­ence in general. Every discipline that aspires to becoming a science must, like physics, have natural laws, and these must be mathematizable.

The fundamental concepts of physics are the following: observation, experi­mentation, laws, theories formed of laws, mathematization, closed world, deter­minism, causality, reductionism.

After physics, however, other disciplines were born, such as cosmology, geol­ogy, psychology, linguistics, philology and history. The first problem that arose in their regard was establishing whether they were sciences in the same way as phys­ics was a science.

Opposed to this distinction was logical positivism, which maintained that only the model of science elaborated by Galileo and Newton could be the basis for a discipline which aspired to becoming a science. The positivists believed that the social sciences were still in their infancy and that they could develop by adopting the models used by the most advanced sciences, like mathematical physics. This entailed that the social sciences must have general laws, nomological models of explanation and prediction, and axiomatic theories. It was precisely the transfer of the hypothetical-deductive method from the natural sciences to the social sci­ences that gave rise to difficulties which severely strained the positivist theory and fuelled criticisms against it.

In identifying the relationship between physics and sociology, both the positivists and their critics ignored biology, as if that science were an embarrassment to both of them. Yet biology—at least as its nature and method have been recently formulated— can shed a great deal of light on the concept of ‘science’ from physics to sociology.

Today biology is a science which enjoys equal dignity with physics. The theory of evolution, genetics, and molecular biology have definitively dispelled doubts concerning its scientificity. However, before achieving its current status, biology had to overcome numerous difficulties.

Since antiquity, philosophers had sought to define life and the characteristics of living beings, and they had put forward the most disparate solutions. Descartes, for example, proposed that the problem of life could be solved by cancelling it: a liv­ing organism, he maintained, is nothing other than a machine.

The majority of naturalists, however, were reluctant to accept this position, and in order to vindicate the autonomy of living beings they concocted the concept of ‘vital force’: just as the planets and the stars were controlled by the invisible force which Newton called the force of gravity, so the motions of living organisms were controlled by an invisible force called the vital force. Those who believed in the existence of this force were termed ‘vitalists’.

Vitalism immediately became popular, and it represented a qualified reaction to Cartesian mechanism. Among its numerous proponents were H. Bergson (1859— 1941) and H. Driesch (1867-1941), who sought, authoritatively but in vain, to demonstrate the existence of a vital force. Lately it has been genetics and molecu­lar biology which have definitively confuted that hypothesis.

Teleology was another obstacle that biology had to overcome before achiev­ing the same scientific status as physics. Vitalism disappeared from biology when it was clearly understood that the experiments intended to demonstrate its exist­ence in reality had failed to do so. But eliminating teleology proved more difficult, mainly because the term ‘teleological’ was applied to diverse natural phenomena. Thus there arose the need to examine the biological and philosophical literature and find a way to classify the term’s different meanings.

E. Mayr demonstrated that four of the five phenomena traditionally considered to be teleological could be entirely explained by science, whilst the fifth phenom­enon, cosmic teleology, did not exist.

The elimination of vitalism and finalism from biology was a first important step towards its foundation as a science with the same dignity as physics.

A second and equally important step was the demonstration that it was impossi­ble to apply certain fundamental principles of physics to biology.

After these centuries-long philosophical vicissitudes, biology now divides into two distinct parts: mechanistic biology (genetics and molecular biology) and evolutionary biology (theory of evolution). The former deals with the physiology of living organisms, in particular the cellular processes (including those of the genome) which can be explained in terms of chemistry and physics. The latter instead has to do with aspects of the living world which concern historical time and evolution. These cannot be explained by the laws of physics or chemistry, but require a specific methodology founded on the historical narrative and on hypo­thetical scenarios. The biological specificity not reducible to physics is given by evolutionary biology.

Having defined the twofold nature of biology, now it is to be established what principles and concepts of physics are applicable to it. From what has already been said it is evident that biology is partly similar to physics and partly different from it.

If biology, with its mechanistic and evolutionist parts, is a science, then it is necessary to revise and enlarge the concept of ‘science’ adopted by Galileo, Newton and the positivists, so that it includes the characteristics typical of evolu­tionary biology.

Unlike physics, biology does not have a mathematical basis. This means that there exist sciences which do not satisfy the requirement of mathematization imposed by Galileo, Newton and the positivists.

Every science is constituted by theories. And theories in their turn are consti­tuted by laws or by concepts. Whilst the theories of physics are constituted by laws, those of biology are constituted by concepts. The most important concepts of biology are those of ‘evolution’, ‘biopopulation’ and ‘natural selection’.

The difference between physics and biology is evident if we compare the nature of living beings with that of inanimate ones. Because of their complexity, biologi­cal systems are endowed with the capacities of reproduction, metabolism, repli­cation, regulation, adaptability, growth and hierarchical organization. Nothing similar exists in the inanimate world of physics.

The concept of ‘biopopulation’ is perhaps the one which best characterizes the difference between the inanimate and animate worlds. The former is constituted by classes whose members are identical, so that apparent variations among them are random and therefore irrelevant. Conversely, in the living world represented by a biopopulation, every individual is unique and unrepeatable. Variation is not irrel­evant but instead crucial for evolution.

From the twofold nature of biology derives a twofold causality: the first cau­sality is constituted by the natural laws that hold for physical and inanimate phe­nomena; the second consists in the genetic programs which characterize solely the living world. There is not a single living phenomenon or process that is not con­trolled by a genetic program contained in the genome. Nothing similar exists in the inanimate world.

A process absolutely unknown in the inanimate world is the natural selection propounded by Darwin to confute the concept of ‘design’ put forward by the natural theologians, and according to whom it is thanks to God’s design that organisms are perfectly adapted to each other and to the environment in which they live. Natural selection, unlike the deterministic laws of physics, was the result of interaction among numerous factors, the principal among them being randomness. Because evolutionary biology—or simply biology, since the specificity of biology resides in its evolution­ary part—is not reducible to physics, it cannot use the latter’s methodology. Biology’s methodology must instead take account of the uniqueness of the phenomena that it studies, like the extinction of the dinosaurs or the origin of the human species. In explaining such phenomena, it cannot resort to laws, nor can it conduct experiments. The extinction of the dinosaurs was a unique occurrence which cannot be derived from a general law nor be subjected to experimentation. The method used to explain it is that of historical narrative, which constructs a scenario whose explanatory capacity is verified on the basis of the existing evidence.

It is thus obvious why reductionism, though essential for physics, cannot be applied in biology. Biological systems are constituted by parts structured into levels which interact with each other. The interactions take place among genes, between genes and tissues, between cells and other components of the organism, between an organism and the inanimate environment in which it lives, and among different organisms. According to physicalism, the higher levels should be reduc­ible to the lower ones, so that their properties can be determined and the system as a whole explained. Applying reductionism to biological systems would deprive the individual levels of their specificity: everything would assume the meaning of the lowest level, namely physics.

The attempt to create a philosophy of biology based on physics was bound to fail. It was therefore necessary to leave the narrow ambit of physicalism to assert the autonomy of biology as a science enjoying equal dignity with physics. The twofold nature of biology has entailed enlarging the concept of science as under­stood by Galileo, Newton and the positivists.

If we were to draw a boundary between the natural sciences and the social sci­ences, we would find that this boundary traverses biology in its middle, connecting its mechanistic part (genetics and molecular biology) to physics, and its evolution­ary part to sociology.

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