The statistical mechanical development of a theory of polymeric systems, developed previously, is reconsidered. The “Stokes law” type of empiricism of the previous development is replaced by the introduction of the concept of “time‐smoothing” the kinetic equations. The introduction of this time‐smoothing affects, in an essential manner, only those expressions of the previous development which involve the distribution function in the configuration space of pairs of molecules. These are the expressions for the “hydrodynamic force” and the term in the expression for the stress tensor which was previously neglected by the “short‐range force” approximation. The present development leads to molecular expressions for the matrix of effective friction tensors, which in the previous development, were obtained through the introduction of the Stokes law type of expression for the hydrodynamic force and the concept of hydrodynamic interaction. In addition, an indication of the effect of the short‐range force approximation is obtained.