 Wittgenstein argues for this making a series of moves to show that to understand an ostensive definition presupposes an understanding of the way the word being defined is used.So, for instance, there is no difference between pointing to a piece of paper, to its colour, or to its shape; but understanding the difference is crucial to using the paper in an ostensive definition of a shape or of a colour.Why is it that we are sure a particular activity—e.g.