  So far, reasons to reject P1 and P3 have been discussed. But one might also question the step from P1 and P2 to C1. As an analogy, suppose that Hare is on a train, looking at a tomato in his lunchbox, and that Tortoise is on the platform, looking at the tomato as the train speeds by. Both Hare and Tortoise have normal vision, in particular, normal visual motion perception. Consider the following argument.