The philosophy of biology is a subfield of philosophy of science, which deals with epistemological, metaphysical, and ethical issues in the biological and biomedical sciences. Although philosophers of science and philosophers generally have long been interested in biology (e.g., Aristotle, Descartes, and even Kant), philosophy of biology only emerged as an independent field of philosophy in the 1960s and 1970s. Philosophers of science then began paying increasing attention to biology, from the rise of Neodarwinism in the 1930s and 1940s to the discovery of the structure of DNA in 1953 to more recent advances in genetic engineering. Other key ideas such as the reduction of all life processes to biochemical reactions as well as the incorporation of psychology into a broader neuroscience are also addressed.
Philosophy of biology today has become a very visible, well-organized discipline - with its own journals, conferences, and professional organizations. The largest of the latter is the International Society for the History, Philosophy, and Social Studies of Biology (ISHPSSB); the name of the Society reflects the interdisciplinary nature of the field. The philosophy of biology can be seen as following an empirical tradition, favoring naturalism. Many contemporary philosophers of biology have largely avoided traditional questions about the distinction between life and non-life. Instead, they have examined the practices, theories, and concepts of biologists with a view toward better understanding biology as a scientific discipline (or group of scientific fields). Scientific ideas are philosophically analyzed and their consequences are explored. It is sometimes difficult to delineate philosophy of biology as separate from theoretical biology. A few of the questions philosophers of biology have attempted to answer, for example, include:
A subset of philosophers of biology with a more explicitly naturalistic orientation hope that biology will provide scientific answers to such fundamental problems of epistemology, ethics, aesthetics, anthropology and even metaphysics. Furthermore, progress in biology urges modern societies to rethink traditional values concerning all aspects of human life. The possibility of genetic modification of human stem cells, for example, has led to an ongoing controversy on how certain biological techniques could infringe upon ethical consensus (see bioethics). Some of the questions addressed by these philosophers of biology include:
Increasingly, ideas drawn from philosophical ontology and logic are being used by biologists in the domain of bioinformatics. Ontologies such as the Gene Ontology are being used to annotate the results of biological experiments in a variety of model organisms in order to create logically tractable bodies of data available for reasoning and search. The Gene Ontology itself is a species-neutral graph-theoretical representation of biological types joined together by formally defined relations.
One subject within philosophy of biology deals with the relationship between reductionism and holism, contending views with epistemological and methodological significance, but also with ethical and metaphysical connotations.
Some philosophers of biology have attempted to explain the rise and fall of reductionism, vitalism, and holism throughout the history of biology. For example, these philosophers claim that the ideas of Charles Darwin ended the last remainders of teleological views from biology. Debates in these areas of philosophy of biology turn on how one views reductionism.
All processes in organisms obey physical laws, the difference from inanimate processes lying in their organisation and their being subject to control by coded information. This has led some biologists and philosophers (for example, Ernst Mayr and David Hull) to return to the strictly philosophical reflections of Charles Darwin to resolve some of the problems which confronted them when they tried to employ a philosophy of science derived from classical physics. This latter, positivist approach emphasised a strict determinism (as opposed to high probability) and to the discovery of universally applicable laws, testable in the course of experiment. It was difficult for biology, beyond a basic microbiological level, to live up to these strictures - Karl Popper for example said in 1974 that "Darwinism is not a testable scientific theory, but a metaphysical research programme." Standard philosophy of science seemed to leave out a lot of what characterised living organisms - namely, a historical component in the form of an inherited genotype.
Biologists with philosophic interests responded, emphasising the dual nature of the living organism. On the one hand there was the genetic programme (represented in nucleic acids) - the genotype. On the other there was its extended body or soma - the phenotype. In accommodating the more probabilistic and non-universal nature of biological generalisations, it was a help that standard philosophy of science was in the process of accommodating similar aspects of 20th century physics.
This led to a distinction between proximate causes and explanations - "how" questions dealing with the phenotype; and ultimate causes - "why" questions, including evolutionary causes, focused on the genotype. This clarification was part of the great reconciliation, by Ernst Mayr, among others, in the 1940s, between Darwinian evolution by natural selection and the genetic model of inheritance. A commitment to conceptual clarification has characterised many of these philosophers since. Trivially, this has reminded us of the scientific basis of all biology, while noting its diversity - from microbiology to ecology. A complete philosophy of biology would need to accommodate all these activities. Less trivially, it has unpacked the notion of "teleology". Since 1859, scientists have had no need for a notion of cosmic teleology - a programme or a law that can explain and predict evolution. Darwin provided that. But teleological explanations (relating to purpose or function) have remained stubbornly useful in biology - from the structural configuration of macromolecules to the study of co-operation in social systems. By clarifying and restricting the use of the term to describe and explain systems controlled strictly scientifically by genetic programmes, or other physical systems, teleological questions can be framed and investigated while remaining committed to the physical nature of all underlying organic processes.
Similar attention has been given to the concepts of natural selection (what is the target of natural selection? - the individual? the genome? the species?); adaptation; diversity and classification; species and speciation; and macroevolution.
Just as biology has developed as an autonomous discipline in full conversation with the other sciences, there is a great deal of work now being carried on by biologists and philosophers to develop a dedicated philosophy of biological science which, while in full conversation with all other philosophic disciplines, attempts to give answers to the real questions raised by scientific investigations in biology.
While the overwhelming majority of English-speaking scholars operating under the banner of "philosophy of biology" work within the Anglo-American tradition of analytical philosophy, there is a stream of philosophic work in continental philosophy which seeks to deal with issues deriving from biological science. The communication difficulties involved between these two traditions are well known, not helped by differences in language. Gerhard Vollmer is often thought of as a bridge but, despite his education and residence in Germany, he largely works in the Anglo-American tradition, particularly pragmatism, and is famous for his development of Lorenz's and Quine's idea of evolutionary epistemology. On the other hand, one scholar who has attempted to give a more continental account of the philosophy of biology is Hans Jonas. His "The Phenomenon of Life" (New York, 1966) sets out boldly to offer an "existential interpretation of biological facts", starting with the organism's response to stimulus and ending with man confronting the Universe, and drawing upon a detailed reading of phenomenology. This is unlikely to have much influence on mainstream philosophy of biology, but indicates, as does Vollmer's work, the current powerful influence of biological thought on philosophy. A more engaging account is given by the University of Chicago philosopher Marjorie Grene.