The term evolution is understood in the classical Darwinian theory and in today’s common synthetic theory of evolution as the gradual, irreversible change of species over generations and time.
This is the distinct difference from the Frankfurt Theory, in which organisms are the evolving units. From the point of view of the philosophy of science, the two statements are two different subject determinations, and the two theories thus have different scopes of validity.
In the 19th century, the question was whether species are constant or changing over generations and tine. Lamarck had already assumed the gradual change of species in 1809: he supposed that each species originated through a spontaneous generation of its own and developed its final design in the course of time and generations. He had thus developed a theory of change, but not a theory of origin and descent.
The explanation for them came only through Darwin. He placed the basis of his theory in the title of his 1859 book: The Origin of Species by Means of Natural Selection.
Darwin argues on the basis of his breeding practice. Here the species already exist, and the individuals are not identical, but rather variants of a species. He saw the natural processes like overproduction of progeny, survival of the fittest: the environment decides who is “fit for life”; the species adapt to the environment. Environmental adaptation and selection are closely linked as a basis for argumentation, and, in this view, become the driving force of evolution. It is no distortion to say: the environment makes the species fitting. That is how Charles Lyell saw it. He stated: were the Earth again to have a climate as in the Jurassic, there would also be dinosaurs again.
Since the species propagate and advance into different environments, one species can become two or more species. With this, Darwin had formulated a theory of origins, a theory of descent.
Modern Darwinism, the “synthetic theory of evolution,” researches the mechanisms and driving forces of change, and in so doing always moves in the field of species. That is the scope of application of this theory, and here it has contributed decisively to insights and findings about population dynamics and the diversification of species. In modern parlance, the individual and the species are considered the result of the information stored on the genes, – “genotype-phenotype.” This results in the definition: evolution is the irreversible change of genomes. The organism (the individual) is nothing but a gene product and a gene carrier (Dawkins: The Selfish Gene).
The Synthetic Theory of Evolution
In the first half of the 20th century, the molecular basis of inheritance and of the change of species was discovered. These results were integrated by classical Darwinism, and the modern Synthetic Theory of Evolution was born.
The Synthetic theory has provided essential insights into population dynamics and species diversification. It continues to work in the field of species, thus maintaining the scope of the original Darwinianism. The genesis of the synthetic theory is well researched and presented several times (Mayr 1984, Junker & Engels 1999; unker 2004).
Darwinism in criticism
Scopes of application: microevolution – macroevolution
The change of species can be explained with the Darwinian theory, but not the origin of the basic types of body design.
Gould calls the level of species, on which the synthetic theory works, „microevolution“ and he stresses that one cannot get any answers for macroevolution, the bauplan-evolution, with microevolution working methods.
Corresponding critical statements were already given in the 1930s by Ernst Cassirer (see Weingarten 1993) and by Wuketits (1988). Mocek (1988) sees „The Becoming of Form“ not explained in Darwinism. Bonik & Gutmann (1981) did not leave it at this criticism and developed the Critical Theory of Evolution, the basis of the subsequent Frankfurt Organismic Theory. Edlinger (2009) goes beyond this point in his critical appraisal of Darwinism and examines the basic positions of synthetic theory, especially the concept of adaptation.
The species is a unit of similar individuals, and in the Darwinian system of arguing it should be essentially shaped by environmental adaptation. All attempts failed to establish a scientific definition of „species“ applicable to all living beings. Already Darwin was aware of the vagueness of the term „speciesIn the end, it remains that a species is what zoologists or botanists consider it to be, so that in fact „species are cultural kinds“ (Gutmann & Janich 1998). The „species“ as a central concept of the Darwinian theory of evolution cannot be defined scientifically. It remains on the field of naturalism. This is true even if one does not speak of species, but of populations and the change of their characteristics controlled by genes.
This central concept of Darwinism takes on an expanded significance in the Frankfurt theory. It is no longer, as was traditionally the case, limited to the relationship between individual (or species) to the environment. Selection is a process on several levels: the level of the molecules, the level of the body structures and their functioning – internal selection — and the level of interaction with the environment in the broadest sense — external selection — which deals with the acquisition of food, use of space, or competition within the species or with other species. (The word selection is not suited to describe the issue because selegere – select is an active verb. This originates in Darwin’s breeding practice. In nature, there is no entity that intervenes actively. Organisms can at most die or die out through their own inadequacy.)
Darwin and Wallace applied this concept to the relationship between the species and the environment, although they themselves saw the explanatory difficulty in explaining this term, namely with the birds of paradise of New Guinea, which had developed quite different species in the same environment.
As the term adaptation is vague, it could be used in an almost inflationary way, as critically compiled by Edlinger (2009). Two suggestions were made to drop the vage term and to talk instead about „viability“ (Edlinger 2009) or „specialization“ (Grasshoff 2014). These two terms refer to the body structure, its ability to work and to its relations to the environment.
In our modern view, it is the mechanical and physiological properties that determine which habitats organisms can enter and where they can live, and they specialize in a specific way of life. They influence their environment through their spatial presence and their turnover of matter and energy. They are the subjects of evolution and not the objects of the demands of the environment.
Genotype — Phenotype
In the view of the Synthetic Theory the individual is the result of the information stored on the genes, it is the „phenotype“ of the „genotype“. This leads to the definition: evolution is the irreversible change of genomes. In this extreme reductionism, — „The Selfish Gene“ (Dawkins) — the genes are the single actuators controlling the chemical conversions and the mechanical construction. In this way, the body structure with its mechanical conditions is completely out of the focus. Therefore, the Synthetic Theory cannot make statements about the evolutionary change of the architecture and the question about the „Becoming of the form“ and of macro-evolution remains unanswered.