For theologians: the October 2005 issue [Vol 85, #4] of the Journal of Religion has a very insightful issue on Frei's use of Midrash against the idea of modern hermeneutics. This might provide some ideas about what we mean when talking about the "plain sense" of scripture.
It is by according priority to the literal sense, and in light of the identity of Jesus Christ that tentatively emerges from our readings, that our own self-understanding and our place in the world can be grasped and articulated, if always in a partial, opaque and humble manner. [p619]
... The contrast with Midrash thus clarifies the distinctive shape of the Christian literal reading, which, in its ascription, is a form of discipleship. The Christian pattern of reading is distinctive because it follows, at a distance, the practice of reading ascribed to Jesus in the Gospel narrative itself. While we cannot describe this pattern exhaustively, several central features can be stated. First, and obviously, it is a practice the typologically reads scripture in ascriptive relation to Jesus Christ, as presented within the Gospel narrative. Second, such ascription requires that the reader lay down her own general, conceptual understanding of salvation, redemption, or the "meaning" of human life, as all such conceptual understandings founder before Jesus's unsubstitutable, narrative identity. Third, one receives new interpretive life in and through narrative ascription. The literal sense, one could say, is the crucifixion and resurrection of hermeneutics, in light of Christ's unique identity. [p629]
... The purality of interpretations in Midrash may thus model the hospitality created by the literal sense as a feature of what "reconstitutes" the Christian community in its distinctiveness and its unity.... One could say that the contingent, pluralistic unity of the literal sense embodies, and makes room for, a contingent, pluralistic unity within the church. [p632]