  Variational principles play a fundamental role in deriving evolution
equations of physics. They are working well in case of nondissipative evolution
but for dissipative systems they are not unique, not predictive and not
constructive. With methods of modern nonequilibrium thermodynamics, one can
derive evolution equations for dissipative phenomena and, surprisingly, can
also reproduce the Euler-Lagrange form of the evolution equations for ideal
processes. In this work, we examine some demonstrative examples and compare
thermodynamic and variational techniques. Then, we argue that instead of
searching for variational principles for dissipative systems, a different
program can be more fruitful: the second law alone can be an effective tool to
construct both dissipative and nondissipative evolution equations.
