Surely we cannot agree with what the Maverick says here. Is the word 'surely' a device of literary bluster, to be used when one is unsure about something, or sure about what one has no right to be sure about? Surely not. 'Surely' frequently occurs in English translations of Aristotle, and practically every sentence of scholastic philosophy contains the word 'patet' (it is clear, obvious) or 'manifeste' (manifestly, clearly) or 'certe' (certainly, surely). Surely these writers cannot have been unsure in using these words, or sure about what they had no right to be sure about?
Though Bill's point certainly raises the interesting question: why say that something is sure, or certain or obvious, when it clearly is sure or certain or obvious? Surely it is redundant? Perhaps it indicates a residual uncertainty after all. I don't know.