It is shown that the original Good-Girifalco derivation of an equation for cos theta (where theta is the contact angle of a liquid on a solid) based on intermolecular force (IMF) theory contains an inconsistency which leads to dependence of cos theta on the term -pi(theta)/gamma(L) (where pi(e) is the reduction in free energy on equilibraton of the solid surface with the vapor of the liquid at its saturation pressure). It is pointed out, furthermore, that the inconsistency has been carried over into the succeeding IMF approaches, such as, for example, that of Fowkes, that of Owens and Wendt, and that of Wu. Reported high experimental values for pi(e) on low-energy surfaces and the possible effect on contact angle prediction are discussed in light of the above and of other factors.