A prominent question in the philosophy of biology is whether biology can be
reduced to lower-level sciences such as chemistry and physics. Materialism is the view that every biological system including organisms consists of nothing except the interactions of molecules; it is opposed to
vitalism. As a methodology, reduction would mean that biological systems should be studied at the level of chemistry and molecules. In terms of
epistemology, reduction means that knowledge of biological processes can be reduced to knowledge of lower-level processes, a controversial claim.
Holism in science is the view that emphasizes higher-level processes, phenomena at a larger level that occur due to the pattern of interactions between the elements of a system over time. For example, to explain why one species of finch survives a drought while others die out, the holistic method looks at the entire ecosystem. Reducing an ecosystem to its parts in this case would be less effective at explaining overall behavior (in this case, the decrease in biodiversity). As individual organisms must be understood in the context of their ecosystems, holists argue, so must lower-level biological processes be understood in the broader context of the living organism in which they take part. Proponents of this view cite our growing understanding of the multidirectional and multilayered nature of gene modulation (including epigenetic changes) as an area where a reductionist view is inadequate for full explanatory power. All processes in organisms obey physical laws, but some argue that the difference between inanimate and biological processes is that the organisation of biological properties is subject to control by coded information. This has led biologists and philosophers such as
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. The old
positivist approach used in physics emphasised a strict
determinism and led to the discovery of universally applicable laws, testable in the course of experiment. It was difficult for biology to use this approach. 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, essential to the
philosophy of evolution. Philosophers of biology have also examined the notion of
teleology in biology. Some have argued that scientists have had no need for a notion of cosmic teleology that can explain and predict evolution, since one was provided by Darwin. But teleological explanations relating to purpose or function have remained useful in biology, for example, in explaining the structural configuration of
macromolecules and the study of co-operation in social systems. By clarifying and restricting the use of the term 'teleology' to describe and explain systems controlled strictly 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. While some philosophers claim that the ideas of Charles Darwin ended the last remainders of teleology in biology, the matter continues to be debated. Debates in these areas of philosophy of biology turn on how one views
reductionism more generally. ==Ethical implications of biology==