[Georges Louis Leclerc de Buffon (1701-1788). The main ideas of his science of life. On the tricentenary of the French naturalist's birthday].

The aim of the paper is construct an outline of G. L. Buffon's ontology, epistemology and theoretical foundations of biology, using the general ideas recovered from and revealed in the voluminous text of Buffon's Histoire naturelle, which underpinned his biology and the natural science of the Age of Enlightenment, and which Buffon never expounded in a separate work. It was deism that Buffon used as a theoretical assumption that could facilitate explaining of where to look for the origin of the uniformity and order that prevailed in nature, and for the source of the natural laws that were being discovered. It was naturalism, a common cognitive attitude among the natural scientists of the Age of Enlightenment, that Buffon expressed in his view that the created and embodied nature was the only object of cognition within whose bounds the cognizant should remain in the process of cognition, by explaining it through itself. Indeed, Buffon made the notion of nature, which sometimes reveals pantheistic overtones, his main theoretical category. The naturalist Buffon was also a universalist in that he conceived of nature as the infinite universe and entered into it cognitively. He proved his universalist stance by (i) propounding the cosmogonic hypothesis, (ii) formulating the concept of life dispersed throughout the universe, and (iii) viewing the process of Earth's formation as one of the many occurring in the universe, and of life on Earth as one of the many biospheres. Buffon was also a determinist, which can be seen in his belief that the object of nature show stability in their mutability, and unity in their variability, which is the effect of immutable laws which belong to the nature of the world. This determinism showed in Buffon's views in three varieties: causal determinism, co-existential (or morphological) determinism and statistical determinism; he did not accept finalism. Buffon was the author of the principle of the conservation of life, according to which the amount of life in the universe is constant, life is an autonomous quality, and animate matter is as ancient as inanimate matter. This principle forms part of the concept of organic corpuscles, a concept which is not without its internal contradictions. Prominent in this concept, the best known among Buffon's theoretical concepts, is the idea of corpuscularism, and ancient concept, related to that of atomism, which found an application in the biology of the Age of Enlightenment in its qualitative variety. Continualism, an idea opposed to that of corpuscularism, manifested itself in Buffon's philosophy in the form of the concept of the chain of being, which Buffon devised basing on one morphological type which was subject to modification. Connected with this latter, specific way of modelling the structure of nature is the notion of species. Species, discovered by Buffon in nature and viewed as existing in nature in a real way, had a physiological character (in that species were formed by individuals that produced a fertile offspring) and endured in an immutable way (irrespective of the suggestion formulated by historians of biology that species were mutable). As a natural scientist, Buffon was an empiric, or even an empiricist. His attempts at experiments, such as the model experiment in trying to develop the cosmogonic hypothesis, are among the rare exceptions. It was this hypothesis, and the history of the Earth that was intertwined in it, that led Buffon to adopt the concept of geological time and to postulate that irreversible events occurred within it, thus discovering something that was reminiscent of the history of human society. Although Buffon used many very general theoretical notions and hypothetical concepts, this broad view of nature cannot be said-- in spite of the opinions of numerous historians--to have formed a system. It does, however, remain a comprehensive vision of nature, an attempt at an ambitious synthesis in the field of natural science.