We have seen two important differences between the treatment of basic propositions in Reformed epistemology and Wittgenstein's treatment of basic propositions in On Certainty. First we saw that these propositions are foundational for the Reformed epistemologist whereas they are not for Wittgenstein. Second, there is a big difference in both cases between these propositions and their relation to the noetic structures, to use Plantinga's phrase, in which they appear. The foundational propositions of Reformed epistemology seem isolated. Though the believer trusts that they are true, they remain always open to the possibility of error. In Wittgenstein, on the other hand, the emphasis is on the way basic propositions underlie our ways of thinking without themselves being subject to doubt and speculation. Wittgenstein says, 'It may be for example that all enquiry on our part is set so as to exempt certain propositions from doubt, if they are ever formulated. They lie apart from the route travelled by enquiry. 1