ABSTRACT
One of the explicit aims of molecular biology is providing a reductive explanation of biological phenomena in terms of molecular mechanisms. Many molecular mechanisms are interlocked into vast networks of partially overlapping mechanisms, where the sharing of mechanistic components is thought to play a role in the fine-tuning of quantitative-dynamic aspects of the phenomena produced by these mechanisms. Molecular mechanisms operate within an intracellular environment filled with other molecules. According to the ontic view, mechanistic explanations are objective features of the world. It is interesting to note that mechanistic explanations do not automatically preclude a role for generalizations and regularities in biology. This chapter describes questions about the levels of composition at which mechanistic explanations bottom-out and top-off–that is, the optimal resolution of detail at which mechanisms should be described and the extent to which mechanisms act as independent modules that can produce the phenomena for which they are responsible when separated from the systems in which they are embedded.
