1 Mechanism schemas and the relationship between biological theories

Current accounts of the relationship between classical genetics and molecular biology favor the ‘explanatory extension ’ thesis, according to which molecular biology elucidates aspects of inheritance unexplained by classical genetics. I identify however an unresolved tension between the ‘explanatory extension ’ account and examples of ‘explanatory interference ’ (cases when the accommodation of data from molecular biology results in a more precise genotyping and more adequate classical explanations). This paper provides a new way of analyzing the relationship between classical genetics and molecular biology capable of resolving this tension. The proposed solution makes use of the properties of mechanism schemas and sketches, which can be completed by elucidating some or all of their remaining ‘black boxes ’ and instantiated via the filling-in of phenomenon-specific details. This result has implications for the reductionism-antireductionism debate since it shows that molecular elucidations have a positive impact on classical explanations without entailing the reduction of classical genetics to molecular biology