Science is concerned both by the utterance of hypotheses concerning the nature of the world, and the verification of these theories as adequate to reality according to an experimental method, which differs according to the domains.
- Structures may belong: Theory
- to the subject: idealism
- to the object: empiricism
- both to the subject and object: constructivism
- exclusively to the relation between the subject and the object: structuralism
- neither to the subject nor to the object: Platonic idealism
Rationalism posits as a principle the dependence of scientific rules established by reason, mainly mathematical, physical, chemical rules, possibly supported by experimental verifications.
It is most often considered that the founder of rationalism is René Descartes, who in the Discourse on the Method (1637) expounded his conception of the scientific method, and developed, in the Principles of Philosophy (1644), his vision of philosophy of science. The proposed method is very personal and deductive, the classification of sciences refers to the situation of the seventeenth century. The conditions in which Descartes developed his system are no longer exactly those of our time.
In a more radical conception, Auguste Comte founded positivism, thinking that the world could be reduced to phenomena explicable by “laws” expressed in mathematical language. This position has been discredited by epistemological criticism. It is often criticized for its subjective bias.
Empiricism posits the principle of dependence on evidence. It is one of the pillars of the philosophy of science, which has developed mainly in the Anglo-Saxon world. Empiricism indicates that knowledge derives directly from the human experience of the world, so that the scientific knowledge comes and remains dependent upon our experiences and observations. Scientific theories are constructed and tested through experimentation, methodical manipulation of experience, using empirical methods. This information drawn from the experience, once gathered in sufficient numbers, can become a consensual basis for the scientific community which posits as evidence its principles, and establishes that these evidences will serve as bases of the scientific explanation. All science is therefore an attachment to empirical experience, to invariant law, which would amount to say, according to some schools of thought, that science is fundamentally a reflexive a priori belief.
Observation involves perception, which makes it a cognitive act, a thought action that also depends on how we can build a rational understanding of the world. If this understanding were to change, then our observations also will change, at least at the appearance stage.
Scientists are trying to use induction, deduction, quasi-empirical methods, or conceptual metaphors to transform this flow of observations into a coherent system.
Scientific realism and instrumentalism
Scientific realism, or naive empiricism, consists in taking the scientific discourse as reality of the world. The term naïve is not pejorative, but indicates that it is a question of sticking to the scientific discourse to apprehend the reality – which is the point of view of many scientists. Thus, a follower of realism will hold for existing electrons and magnetic fields.
Unlike realism, instrumentalism argues that our perceptions, scientific ideas and theories do not necessarily reflect the perfect reality of the world, but that they are useful means to explain, predict and control our experiences. According to an instrumentalist’s point of view, electrons and magnetic fields are convenient ideas whose existence is contingent. Instrumentalism comes in part from John Dewey’s pragmatism.
In fact, this current analyzes that science uses “explanatory hypotheses”, in other words, theories that have “hitherto” been able to predict observations.
Let’s take an example :
When we drop an object, our experience tells us that it falls in a certain direction. A first theory could postulate (unlike that in force today) that a force attracts objects without variation in their size and always in the direction given by our first test. As long as the experiments only apply to objects of identical mass and in a reduced space (a garden for example) which does not suggest that the direction changes according to the masses of the surrounding objects, it is possible to use successfully this first explanatory hypothesis, however false.
In the field of epistemology, constructivism is a stream of thought based on the idea that our representations, our knowledge, or the categories structuring these knowledge and representations, are the product of the human understanding. Constructivism joins in its approach instrumentalism and pragmatism.
In sociology, social constructivism is at the intersection of different currents of thought and was presented by Peter L. Berger and Thomas Luckmann in their book The Social Construction of Reality (1966). It seeks to discover how social reality and social phenomena are “constructed”, that is, the way in which these phenomena are created, institutionalized and transformed into traditions.
Analysis and reductionism
Analysis consists of splitting an observation or theory into simpler steps or concepts in order to understand it. Analysis is essential to science, just as to any rational enterprise. For example, it would be impossible to describe the motion of a projectile mathematically without separating the force of gravity, the projection angle and the initial velocity of the moving body. Only the separate analysis of these components, then their regrouping into a system, makes it possible to formulate a theory of practical movement.
Reductionism in science can have different meanings. One type of scientific reductionism consists of the belief that all fields of study can ultimately be reduced to a purely scientific explanation. Thus, a historical event can certainly be explained in sociological or psychological terms; from a reductionist point of view, this explanation can be described without loss of meaning in terms of human physiology, which itself can be described as the result of chemical or physical processes, so that the historical event is reduced to an event of physical science. This would imply that the historical event was nothing other than the fruit of a physical schema, which denies the existence of independent spontaneous phenomena. Physicalism is the reduction of all phenomena to phenomena that can be explained by physical laws.
In the simplest and shortest reductionism, by the suffix “ism” which designates a doctrine, consists in bringing back the “complex” to the simple, as a two-dimensional photograph of a three-dimensional statue, the biological complexity to the mechanical simplicity. Reductionism is not Occam’s razor-saving ruler.
“[…] Reductionism: To account for known data, any scientist must provide the simplest possible explanation, the most economic and (usually) the most elegant possible. But reductionism becomes a defect if we attach excessive importance to the principle that the simplest explanation is the only one possible, sometimes the data must be considered in a larger Gestalt “. (Gregory Bateson, “Nature and Thought”).
Daniel Dennett showed that total reductionism was possible, while stressing that it would be a “bad science”, seeking to demonstrate too much from too little. The arguments against such reductionism are based on the idea that self-referenced systems contain more information that can be described by individual behaviours, or as part of that of a group, than the other systems. Concrete examples are fractal organizations or self-evolving systems discovered in chemistry. But the analysis of such organizations is necessarily destructive for information, because the observer must first select a sample of the studied system, which may be partially only representative of the coherent whole. Information theory can be used to calculate the extent of information loss; it is also one of the techniques applied in chaos theory.
Scientific realism and metaphysics of science
The metaphysics of science is the project of developing a coherent and complete vision of nature on the basis of scientific theories. Science is not built on a foundational base – an absolute point of view – but it is in perpetual constitution (the Neurath ship). The metaphysics of science, which belongs to analytic philosophy, no longer consists solely in the analysis of language, but more broadly in a systematic and argumentative discourse aimed at understanding the world and the position that the human being occupies in it. Pursuing Plato and Aristotle, it develops general categories that seek to grasp the being of the empirical world (see Aristotle, Metaphysics, Book 4) from a powerful anchoring in the sciences. This project is a form of scientific realism characterized by:
- a metaphysical proposition: the existence and construction of nature are independent (ontology and causality) of scientific theories.
- a semantic proposition: the constitution of the nature says which scientific theories are reliable (term preferred to “true” because science is in perpetual construction) and therefore which are not true (here the term is opportune).
- an epistemic proposition: sciences are, in principle, capable of giving cognitive access to the constitution of nature. There are two discussions: one on the under-determination of theory by experience (Pierre Duhem, 1906, Willard Van Orman Quine, 1951). The other relates to cognitive leaps linked to the great advances that have been observed in the history of science (twentieth century).
This project of metaphysics of science has at its disposal the universal and fundamental theories acquired since Newton, some of which are deterministic and others probabilistic (privileged position of physics). Special science theories are not universal and depend on the theory of fundamental physics. Contrary to the theory of fundamental physics for which a principle is applied to a causal, nomological and explanatory completeness, the theories of the special sciences are not complete.
Four metaphysical positions are possible related to 2 distinctions (David Lewis):
- Intrinsic properties (atomism) or relations in a structure (holism).
- Categorical properties (purely qualitative) or causal properties (generating by their very nature certain effects)
Two other distinctions were also examined: properties as universals and properties as modes.
After examining the distinctions, special sciences such as quantum mechanics and biology in particular as well as philosophical currents of science as scientific realism, Michael Esfeld concluded by taking care to recall the vassalage of philosophy on the state of knowledge of the science in the process of becoming and advising the avoidance of dynamics that lead “to very dubious ontological commitments (such as the one postulating the existence of an infinity of parallel branches of the universe) [and which prevents] from succeeding to a coherent vision of fundamental physics and special sciences.”