The Collaborative International Dictionary of English v.0.48:

Voluntarism \Vol"un*ta*rism\, n.
   1. (Philosophy) Any theory which conceives will to be the
      dominant factor in experience or in the constitution of
      the world; -- contrasted with intellectualism.
      Schopenhauer and Fichte are typical exponents of the two
      types of metaphysical voluntarism, Schopenhauer teaching
      that the evolution of the universe is the activity of a
      blind and irrational will, Fichte holding that the
      intelligent activity of the ego is the fundamental fact of
      reality.
      [Webster 1913 Suppl.]

   2. The principle or practice of depending on volunteers to
      support institutions or perform some desired action.
      [PJC]

   3. A political philosophy opposed to dependence on
      governmental action or support for social services that
      might be performed by private groups.
      [PJC]