 Although the mechanics of this part of supposition theory are well understood, in Ockham and in other authors, its exact purpose remains an open question. Although at first the theory looks like an account of truth conditions for quantified propositions, it will not work for that purpose. And although the theory was sometimes used as an aid to spotting and analyzing fallacies, this was never done systematically and the theory is in any event ill suited for that  purpose.[21]