 Those points on the boundary line are neither black nor non-black. Consider the propositions “Point O is black” and “Point O is not black” (where point O is on the boundary line of a black blot). Neither of them is true, but false, either. These are prime examples of Peirce’s L-proposition. Using Peirce’s own truth-tables in the previous subsection, let’s compute the truth value of “Point O is black or point O is not black”.