The classical Chapman-Enskog expansion provides a bridge between the kinetic description of gas dynamics and continuum mechanics. However truncation of this expansion beyond (first) Navier Stokes order yields instability of the rest state. A special case of Chapman-Enskog is obtained when the constraint of constant density is imposed: the Rivlin-Ericksen fluid which of course exhibits the same instability phenomena upon truncation. This talk illustrates how an approximate sum of the Chapman-Enskog expansion eliminates the instability paradox via derivation of a generalized Clausius-Duhem inequality.