At the end of the eighteenth century, in the Metaphysical Foundations of Natural Science , Kant argued that the only "true" sciences were those that could be given a mathematical foundation. He exempted psychology from the true sciences, arguing that no mathematical analysis could be given of the occurrence of thoughts and ideas. Johann Friedrich Herbart and others in the tradition of empirical psychology (later including Wundt, Fechner, and Weber) took Kant's words as a challenge, coming up with ways to quantify sensation and perception and to test them experimentally. But Kant's more fundamental distinction between mathematically based, a priori sciences and inductive, a posteriori sciences based on observation lingered.The schools of neo-Kantianism that followed took differing positions on Kant's stance. The Southwest School, or Baden School, argued for a dualism between nature and value, taking the position that beyond the objects present to us, there are also meaningful and valid relations of valuation. The realm of value can be treated scientifi cally as well ( Š uber 2009 : § 14.2.2).