Scientific Discovery: Between Incommensurability of Paradigms and Historical Continuity

Discoveries in physics imply two elements. The firstone is the belief that formal tools, already foundedin the framework of existing mathematical theories,may offer the solution to a puzzling anomaly. Thesecond one is the ability to assign a physical meaningto the adopted formalism, and to consider all itstheoretical implications.Discussing an historical case where the adoption of aparticular formalism represents the real motor of thecreative intuition, we mean to delineate scientificdiscovery both as a discontinuous change with respectto previous achievements and as a linear process ofknowledge enrichment.On March 1948, during the Pocono conference thatfollowed the one held in Shelter Island, Feynmananalysed the electron-photon interaction formulatingit in terms of the Lagrangian formalism. Thedevelopment of Feynman's idea draws attention to thepoint that novel theoretical discoveries may be theresult of applying existing formal tools. They may bethe result of giving different interpretations toprevious scientific thinking (according to thehermeneutical point that not even scientific textshave a single, absolute meaning but are given amultiplicity of possible readings by different peoplein different contexts).