If one wants to investigate the development of biology into its modern shape, one must surely study the works of Buffon. Including him in a discussion of philosophy might seem less reasonable, but considering the importance of Darwin's theory of evolution to a modern way of thinking and Buffon's value as a step towards Darwin, his inclusion seems more understandable.
Buffon's main work is Histoire naturelle, a huge, multivolume study on such varied topics as cosmology, geology and biology. Going through all of these volumes would be an arduous task, and so I've chosen to read only a selection of what should be especially philosophical portions of Buffon's works. Even in comparison with this selection, my post will be just a quick summary of some interesting features found in Buffon's writings.
We might begin from Buffon's methodological remarks. Buffon sets out himself between what he considers two faulty extremes. First of these extreme was symbolised by Aristotle, who according to Buffon had no real method at all in his biological writings – he just enumerated arbitrary observations on the behaviour of animals, without trying to make the observations into a coherent system. The other extreme, on the contrary, tried to use an artificial, rigid and external classification for making sense of the living world – Buffon mentions especially Linné as a representative of this group. Buffon's own attempt is to find natural classification and systemification of nature. Of course, one cannot just directly start from such a classification, but one can still try to proceed toward such a classification – man-made classifications are only a starting point, which must be constantly compared with empirical data.
A good example of Buffon's reliance on empirical data is his attitude towards the history of Earth. While some of Buffon's contemporaries still tried to fit Earth's development with the account of Genesis, Buffon wanted to justify his view of Earth's history more through proper research. Of course, he still wasn't ready to throw out all of the Bible and accepted, for instance, the idea of a worldwide deluge. Yet, he didn't base this idea merely on Bible, but also noted how fossils of sea animals could be found on dry land.
Fossils were indeed an important piece of evidence for Buffon, because they show that animals of previous times have been different than they now are – elephants of ancient times (mammoths, that is) were considerably larger than they current counterparts. Buffon still isn't an evolutionary thinker, but believes that there has been a fixed number of species since the generation of life on Earth. These species could have varied in their features and especially they might have degenerated, like elephants have become smaller – earlier Earth had more vigour in producing animals, Buffon explains. Still, no truly new species is ever born. Here he justifies once again his statement through fossils – all species of current times have been found from fossil sources.
Although Buffon believes in the fixedness of certain genera of living things, he does think there is a certain continuum of life. For instance, he suggests that there is no clear division between plants and animals, because certain entities, like corals, share features of both animals and plants. Somewhat inconsistently, Buffon then insists on a leap from the level of animals to the level of human beings. While animals are irrational, human beings are rational, and there cannot be any middle road between irrationality and rationality. This very traditional division implies, according to Buffon, that while for animals mere satisfaction of physical desires is enough, human happiness relies on harmony between reason and sensuous impulses.
The most intriguing aspect of Buffon's thought is then how he manages to unify quite revolutionary ideas with some rather traditional and even conservative thoughts. Earth and especially its living denizens have a history, but this history does not entail that all species are related to one another.Living beings form a continuum, but humans are still far removed from other species.
As most of Buffon's works concern rather specific questions of biology and other particular sciences, I shall leave my account of his work to this rather general level and turn again to American philosophers.