[en] Highlights: • A ‘consistent’ KS-DFT obtained by insisting IP condition for all occupied orbitals. • IP condition fixes Kohn-Sham potential for each orbital. • IP condition is a consequence of adiabatic TDDFT. • This also means that the ‘multi-electron self-interaction’, is mitigated. Once electron correlation is included in an effective one-particle operator, one has a correlated orbital theory (COT). One such theory is Kohn-Sham density functional theory (KS-DFT), but there are others. Such methods have the prospect to redefine traditional Molecular Orbital (MO) theory by building a quantitative component upon its conceptual framework. This paper asks the question what conditions should such a theory satisfy and can this be accomplished? One such condition for a COT is that the orbital eigenvalues should satisfy an ionization theorem that generalizes Koopmans’ approximation to the exact principal ionization potentials for every electron in a molecule. Guided by this principle, minimal parameterizations of KS-DFT are made that provide a good approximation to a quantitative MO theory.