 Another central idea of Ludwig’s program is the description of intra- and inter-theoretical approximations by means of “uniform structures”, a mathematical concept lying between topological and metrical structures. Although this idea was later adopted by the other structuralistic programs, it plays a unique rôle within Ludwig’s meta-theory in connection with his finitism. He believes that the mathematical structures of the infinitely large or small, a priori, have no physical meaning at all; they are preliminary tools to approximate finite physical reality. Uniform structures are vehicles for expressing this particular kind of approximation.