A Possible Generalization of Onsager’s Theory

It is known that Onsager’s symmetry relations for linear irreversible processes are without meaning unless a criterion for the proper choice of fluxes and forces is given. Author proposes such a criterion. He then establishes some extremum principles which are equivalent to Onsager’s theory. These principles are compared with former ones, and it is shown that they provide a basis for the generalization of Onsager’s theory to nonlinear processes.