Following the suggestion of Goryachev in seeking a formulation of binary spinodal decomposition which better accords with the tenets of irreversible thermodynamics and with the experimental and computational modelling record we have revised de Fontaine＇s ternary version of Cahn＇s binary linearized theory. This modification was motivated by the fact that his version with Bragg-Williams thermodynamics does not accommodate the formulation of a differential initial value problem since the two 2 x 2 coefficient matrices cannot be simultaneously brought to the diagonal. In the time-dependent Ginzburg-Landau representation suggested by Goryachev the corresponding matrices are proportionate, abetting commutation and therefore simultaneous diagonalization well into the high amplitude range of decomposition. This suggests the need for revision of ternary small angle scattering theory. (C) .2000 Kluwer Academic Publishers.