Major Stages of the Conceptual History of Systematics
Different emphases on the conceptual history of systematics inevitably lead to a significantly different understanding of its main stages that are acceptably considered scientific revolutions. Thus, botanists usually distinguish two main stages in this history, viz. the epochs of artificial and natural systems [Sachs 1906]. Proponents of the evolutionary idea divide the entire systematics into pre-evolutionary and evolutionary [Mayr 1942, 1969, 1982]. A variant combining these two versions is a partition of the history of systematics into artificial, natural, and phylogenetic stages [Starostin 1970]. Within the framew'ork of empirical history, it is popular to distinguish three main stages, denoted as alpha-, beta-, and omega-systematics: the first (initial) corresponds to descriptions of local fauna and flora, the second to the construction of general classifications, and the third (final) to the development of a comprehensive overall classification [Mayr 1942, 1969; Davis and Heywood 1963; Stace 1989]. The ideologists of biosystematics distinguish between descriptive, systematic, and biosystematic stages in the history of systematics [Valentine and Love 1958]. Theoreticians of the numerical program believe that its development in the second half of the 20th century became the most significant achievement almost since the time of Linnaeus [Sneath 1995; Vernon 2001], while the devoted cladists argue that the most significant is the cladistic revolution that also occurred in the second half of the 20th century [de Queiroz 1988].
Based on the above general ideas about what the history of systematics is and how it can be presented, four main stages can be quite naturally distinguished: presystematics, proto-systematics, scholastic systematics, and post-scholastic systematics [Pavlinov and Lyubarsky 2011; Pavlinov 2018, 2019]. The first two are united in the “prehistory” of the scientific systematics, whereas the last two correspond to the development of the scientific systematics proper. The principal feature of the latter is that research programs dealing with rational exploration of the Natural System of living nature begin to develop. As noted, changes in such programs, dominating at one stage or another in the development of theoretical systematics, have the character of scientific revolutions, signifying transitions from one historical stage to another.
Pre-systematics begins with the history of all human classification activities; it is known as folk systematics, characteristic of communities of indigenous people. It is developed on various local ethnic bases and, in its foundations and aspirations, is not abstractly cognitive but mostly empirical and pragmatic, without explicitly expressed onto-epistemic premises.
Proto-systematics is immersed in a broader context of ideas about both the ordered Cosmos and ordered ways of its knowing; an idea of Cosmos means that protosystematics, in contrast to pre-systematics, is by its scope global rather than local. Within the framework of this context, two key tasks are solved, laying down two already-mentioned basic cognitive programs: (a) “methodical” is associated with the rational development of the first onto-epistemic principles of any cognitive activity; and ( b) “collectionist” is associated with the primary systematization and generalization of information about living nature, partly in a “cosmic” and partly in a utilitarian sense. In proto-systematics, several stages can be quite naturally distinguished, viz. primary (Antique), scholastic (Medieval), and herbal (Renaissance). In the first, certain general principles of logical classification and related basic notions are developed, viz. genus, species, essence, difference, etc. In the second, the main rational categories of onto-epistemology, basic argumentation schemes, and classification methods become more advanced; all of them will be inherited by theories of early scientific systematics. Renaissance herbalistics mainly develops the “collectionist” program, thus laying the foundations of descriptive systematics.
Scientific systematics begins with the shift from natural theology to natural philosophy (in its broad sense) in the 16th century, with the development of a new cognitive situation and cognitive paradigm of exploration of Nature. The main goal becomes the latter’s rational cognition aimed at uncovering a certain universal natural law that organizes the entire material world into the System of Nature. In systematics, the key task becomes the recognition of the natural groups of organisms in which this System is manifested. According to the way this general cognitive intention is filled, the conceptual history' of systematics can be divided into several stages, each initiated by the respective scientific revolution.
The first stage covers the 16th-18th centuries and is largely associated with the development of classification methodology borrowed from Medieval scholasticism. It begins with a specific initial rationalization of the branch of natural philosophyexploring plants and animals, which leads to the scholastic revolution and to the emergence of systematics as a scientific discipline. As a result, scholastic systematics appears to deal with a global rational systematization of living nature instead of just listing its facts and uses. The respective classifications of plants and animals are elaborated based on the logical genus-species scheme, with the essences of organisms being used to recognize their natural groups. An adaptation of this scheme to the exploration of living matter becomes the characteristic trend of the conceptual history of scholastic systematics, with the main debates being about the principal essences of organisms. As one of the important results of this trend, the hierarchical system of fixed ranks is developed to replace the rankless hierarchy of the genus-species scheme.
Post-scholastic systematics begins to emerge in the second half of the 18th century as a result of the post-scholastic revolution that becomes a kind of protest against the previously dominant scholastic approach to the comprehension of the Natural System. It is flagged by a transition from the main emphasis on the scholastic method of cognition of Nature, with organisms being characterized by a few essences, to Nature itself in all its manifestations, with organisms being characterized by all available characters. This new cognitive situation yields a certain harmony of “methodical” and “collectonist” programs and means “biologization” of systematics, thus making it biological in a full sense. This change is largely due to the empirization of taxonomic research: the predominantly deductive (“top-down”) classification method is replaced by the predominantly inductive (“bottom-up”) one. This general trend gives rise to a significant variety of particular taxonomic theories, differing in their natural philosophies (from “systemic” to “ladder,” from typological to early transformist, from organismic to numerological, etc.) and methodologies (the ratio of inductive and deductive elements, different approaches to character weight). The most noticeable and influential become natural systematics (in its narrow, mostly botanical content) and classification typology, each claiming to be most “natural” in its classification theory and method.
In the second half of the 19th century, an important step in the development of post-scholastic systematics brings it from an early to a more mature stage. It is marked by an active assimilation of the transformist natural philosophy in its historical understanding and, on this basis, by the adoption of the genealogical meaning of the Natural System. This step marks the evolutionary revolution in the conceptual history of systematics giving birth to evolutionary interpreted systematics. Darwin’s model of evolution attracts taxonomists’ interest in intraspecific categories, while Haeckel’s model focuses mainly on high-rank groups.
Throughout the 20th century, the development of systematics is largely associated with the search for answers to the challenges of new versions of scientific rationality. In the first half of that century, ideas of the positivist philosophy of science become dominant in systematics: this philosophical shift causes a positivist revolution in systematics and the emergence of the positivistically oriented taxonomic thought. The latter’s development first leads to the formation of biosystematics based on the Darwinian evolutionary model. Somewhat later, classification phenetics and numerical systematics are formed in conjunction, and to a certain extent lead to the debiologization (formalization) of the positivist systematics.
In the second half of the 20th century, there is an active rethinking of the phylogenetic concept, which marks the next significant step in the conceptual history of contemporary systematics deserving being called a post-positivist revolution. The main tone is set by the cladistic version of phylogenetics, which absorbs significant elements of positivist reductionism. Towards the end of the 20th century, its development is governed mostly by its active “molecularization,” i.e., the assimilation of molecular data together with new numerical methods [Lee 2004]. This results in the absolute dominance of genosystematics (better known as molecular phylogenetics); because of ignorance of all other biologically significant features of organisms (such as morphological, physiological, developmental, etc.), this appears to be another manifestation of the debiologization of our discipline.
Along with these “mainstream” research programs of post-scholastic systematics, each pretending to be “revolutionary,” taxonomic theories of more particular significance emerge over the two centuries of its conceptual history. In the 19th century, these are “esoteric” theories like numerology and organismic natural philosophy. In the 20th century, several variants of rational systematics (in its broad sense) are formed, implementing in different ways the general idea of nomotetization of this discipline. Along with them, biomorphics emerges, paying most attention to the life forms (ecomorphs). Finally, in recent years, a new taxonomic theory seems to begin to assert itself, based on the ideas of evolutionary developmental biology (evo-devo).