Darwin's contrivances: orchids, evolution and scientific ethics in the philosophy of science of XIX century

With Orchid book Charles Darwin was able to accurately explain and demonstrate the evolutionary mechanisms underlying flower adaptations and, at the same time, to build a philosophical dimension for natural history. Asa Gray was one of the first to perceive that Orchid book might undermine theological explanations of nature and he described it as "a flank movement on the enemy". Darwin accepted such description implying that he intended to attack natural theology: but there is a debate whether he and Gray had the same "enemy" in mind. I will try to demonstrate that the flank movement was, before than a direct attack on natural theology, a clever and scrupulous attempt to convince scientists of the validity of Darwin's science exposed in Origin. This attempt didn't consist only in the ability to respond to the criticisms of the theologians and philosophers of science. Darwin was able to convince scientists first of all through the methodology imposed on his work: Orchid book was the result of 20 years of a "patient observation" and "accuracy of reasoning", the proposed results were original and showed how advantageous the study of organisms was for natural history under the belief of the modification of species. Among all his post-Origin researches, Orchid book provided a weapon to counteract the destructive and widespread criticisms that the theoretical results of Origin had been obtained. However there are other historical-scientific aspects that we can discover in Orchid book and made the flank movement irreducible to a theological dispute over the fixism and transmutation of species: the place of religion and finalism in the working life of scientists, the meaning of evolution in the professionalization and institutionalization of biology, the emergence of ecology, the historical role of orchids in political and social beliefs of nineteenth-century, the research for practical and theoretical tools for classification, the possibility of observational predictions in botany, the reference to graphic examples to observe the results of natural selection, innovations in agriculture for horticulturists and a new way of interpreting the beauty of nature emancipated from the explanations of natural theology. This leads to a multi-component approach for the clarification of the meaning of the flank movement that makes complementary all the aspects above described. Following this model I will try to show that if we want to give an historical justification for the conversion of botanists to darwinian side of explaining natural history, we have to conceive the flank movement as a mosaic of interactive historical, philosophical and biological components. The core of my argument is that through the choice of orchids as subject for a book in Victorian age and the demonstration that this book allowed new ways for studying classification of species, coevolution, the relationship between function and design in morphology, homologies and natural selection from the perspective of common descent, Darwin managed to convince the scientific community to which he belonged that Origin's generalizations were correct and/or that he never had betrayed the inductive method