 In sections 2–4, we discussed three sets of argument for the thesis that there are singular propositions. The first, the modal argument, was broadly linguistic in nature and the other two, the arguments from indexicals and reduplication, were pyschological. But singular propositions also give rise to a number of important metaphysical problems, in addition to those involving propositional attitudes and apparent substitution failures already discussed. We end this essay by discussing two related problems: Modal problems and temporal problems.