A Step Aside: Positivist Revolution
At the end of the 19th and in the first half of the 20th centuries, natural science is developing under a strong influence of positivist philosophy, dating back to the philosophical empiricism of the 16th century (F. Bacon, J. Locke, etc.) and finally taking shape in the second half of the 19th century (O. Comte, E. Mach, etc.). The central idea is that true scientific knowledge can only be achieved by the inductive scheme of argumentation: at the heart of everything is empirical data, generalizations arise on their basis, all kinds of a priori judgments about the “nature of things” must be discarded, everything complex must be decomposed into elementary “bricks,” and the relations between them serve as the basis for explaining complex things. An ideological core of this philosophy of science is so-called physicalism, according to which any judgments about natural phenomena deserve to be considered scientific if they are substantiated by means and expressed in the language of physics, including employment of experimental evidence and mathematical apparatus.
Against this background, new biological disciplines make it possible to take a significantly different look at organisms and at relations between them; with this, they correspond, to a greater or lesser degree, to the physicalist understanding of the content and principles of natural science. First of all, genetics should be mentioned here, in which an organism is reduced to a “sum of genes” and thus the evolutionary issues are transferred from the level of organism to the level of genetic units. This reductionist trend is reinforced by biochemical studies making it possible to compare organisms not by anatomical (macrolevel) but by biochemical (microlevel) features. Finally, the emergence of ecology, in which the main emphasis is placed on the processes occurring in local populations, also becomes an important novelty of the “new biology.”
Because of all this, classical biology associated with the study of the diversity of organisms at just the macrolevel appears to be outside the realm of science thus understood. This concerns first of all classical systematics, which is assigned the role of the Cinderella of the “new” natural science. Thus, Sinai Tschulok divides biology into biophysics (exploring “real” relations) and biotaxonomy (exploring “imaginary” relationships) [Tschulok 1910]; similarly, the ecologist Eugene Odum divides biological disciplines into fundamental and taxonomic [Odum 1953]. Classical systematics is criticized as purely descriptive by the founders of the onto-rational doctrine [Driesch 1908; Lyubishchev 1923]; developers of new' taxonomic ideas and approaches (biosystematics, numerical phenetics) reject it as “morally obsolete” [Turrill 1940; Gilmour and Turrill 1941; Mayr 1942; Heslop-Harrison 1960; Michener 1962; Sokal 1966]. The growing influence of the Darwinian micro-evolutionary theory also plays a significant role in the decline of interest in classical systematics: its interpretation of the causes of the diversity of organisms appears to be more compatible with physicalist philosophy and makes the general concept of the Natural System completely redundant.
Progressive rationalization of systematics in a new guise, trying to respond to the challenges of the new philosophical scientific context, becomes the most noticeable trend of its conceptual history during the first half of the 20th century. The emergence of this “new' rationality” marks a drastic shift from the old to a new cognitive situation in systematics, which can be called the positivist revolution [Pavlinov 2018, 2019]. Accordingly, as a result of the latter, something like positivist systematics is shaped; this term designates a certain cognitive program of a physicalist kind, and within its scope several particular research programs are formed. The article “Taxonomy and Philosophy” by the botanist John Gilmour appears in a festschrift with the iconic title The New Systematics [Huxley 1940a] to become a kind of “positivist manifesto” for this revolution [Gilmour 1940]. The symposium “Philosophical Basis of
Systematics” organized by the Society of Zoological Systematics (USA) in 1961 (materials published in Systematic Zoology, vol. 10, issue 4) clearly shows the dominance of positivist ideas in the theoretical systematics of this time.
This movement of systematics towards a new rationalization is most clearly evident from the attempts to re-formulate its onto-epistemic foundations. On the one hand, the task of its nomotetization is designed to make classifications by status similar to physical or chemical laws [Driesch 1908; Lyubishchev 1923, 1972, 1975; Ho 1990, 1992; Ho and Saunders 1993, 1994; Webster and Goodwin 1996; Zakharov 2005]. On the other hand, attempts at axiomatizating systematics and building its foundations by employing more rigorous formalisms become more accentuated [Woodger 1937, 1952; Thompson 1952; Gregg 1954; Mahner and Bunge 1997; Pavlinov 201 la, 2018].
An active assimilation of research methodologies of a physicalist kind becomes another important response of systematics to these new challenges: this includes issues in experimental (reliance on experiments with organisms or their derivatives), numerical (reliance on the aphorism “mathematics is the queen of all sciences,” by Carl Gauss), and phenetic (substantiated by direct reference to the elementarist background of positivism) systematics. One of the first becomes biosystematics, w'hich grows out of classification Darwinism [Hall and Clements 1923; Camp and Gilly 1943; Camp 1951]. In it, all discussions about species and supraspecific taxa, phylogeny, and homology are discarded as “unscientific”; the main emphasis is placed instead on classifications of intraspecific categories. A prerequisite for this is the interpretation of populations as the key units of the ecological communities and the real actors of the evolutionary process. Among its important parts are new approaches to solve systematic tasks based on ecological, hybridological, and immunogenetic experiments. Penetration to the subcellular level gives rise to several branches of biosystematic studies that can be called “character-based”; these are chemosystematics (analysis of chemical compounds, including macromolecules), karyosystematics (analysis of chromosomes), etc.
One of the most important parts of the positivist revolution in systematics becomes a combination of phenetic and numerical ideas: this gives rise to numerical phonetics, which ties biological systematics most closely with the philosophy of physicalism. It is the maturation of these ideas that their supporters declare to be another revolution in systematics estimated as almost greater than the previous “Darwinian” one [Sneath 1995]. Quantitative methods for demarcating populations developed by biosystematics are the first step in this direction, though elaborating full-fledged classifications on a quantitative basis is not presumed at this step [Simpson and Roe 1939]. Such a task for “exact systematics” is set for the first time by the zoologist Evgeny Smirnov in the 1920s-1930s [Smirnov 1923, 1938], but his approach does not become popular because of its typological terminology. Actually, the beginning of this “revolution” is laid by a series of works by zoologist Robert Sokal and microbiologist Peter Sneath, and the appearance of another “new systematics” is immediately announced [Michener 1962], with the book Principles of Numerical Taxonomy becoming a kind of “gonfalon” [Sokal and Sneath 1963]. In the second half of the 20th century, the development of computer technology, including ready-to-use computer programs with standard statistical and classification methods, leads to a nearly total “numericalization” of most of systematics. New high-performance computers make it possible to process large amounts of data, which causes the announcement of the emergence of yet another “new systematics” stimulated by quantitative processing of “big data” [Schram 2004]. These newest instrumental developments in systematics are considered to mark the early stages of a technology-driven revolution [Wilson 2005], resulting in cybertaxonomy that deals with processing data and metadata on biodiversity using standard electronic tools [Smith 2013; Wheeler and Hamilton 2014].
The biosystematic research program is being developed mainly by botanists and retains a fairly large influence on botany to this day [Lines and Mertens 1970; Takhtadjan 1970; Hedberg 1997; Feliner and Fernandez 2000]. Numerical phenetics in its pure form turns out to be very limited in its effective application to microsystematic research only and, because of this, fades away from the 1970s. However, its principal ideas are in demand in the currently dominant “new phylogenetics,” which flourishes within the framework of post-positivist systematics.