The success of empiricism in accounting for our knowledge of the tri-dimensionality of the physical world is intimately connected with its ability to refute Kant's claim that the existence of such similar but incongruent counterparts as the left and right hands constitutes evidence for his transcendental a priori of space.¹ Since the reasons for the untenability of this particular Kantian contention are not given even in Reichenbach's definitive empiricist critique of the transcendental idealist theory of space² and are not sufficiently known to the philosophical public, I shall give a brief statement of them.