  A theoretical scheme, based on a probabilistic generalization of the
Hamilton's principle, is elaborated to obtain an unified description of more
general dynamical behaviors determined both from a lagrangian function and by
mechanisms not contemplated by this function. Within this scheme, quantum
mechanics, classical field theory and a quantum theory for scalar fields are
discussed. As a by-product of the probabilistic scheme for classical field
theory, the equations of the De Donder-Weyl theory for multi-dimensional
variational problems are recovered.
