The history of twentieth century physics is interpreted as the result of a consistent undertaking by the scientific community to retain for this discipline the characteristics of a science "of laws", by excluding from its domain all those phenomena and theories which could have introduced into physics some features of the sciences "of processes". A brief survey of the roads abandoned as a consequence of this choice is presented, together with a short review of recent attempts to formulate a theory equivalent to Quantum Mechanics by using the theory of stochastic processes.