In the mid-1760s, Johann Heinrich Lambert wrote a letter to Kant who offered cooperation with a view to reforming metaphysics. Based on the short correspondence between the two philosophers, it can be shown that this cooperation could never really come about. Nevertheless the thesis was sometimes put forward in research that Lambert had a defining influence on Kant’s Metaphysical Foundations of Natural Science, also, and above all, with regard to the Newton-critical moments of this natur­al theory. However, this thesis can (...) only be confirmed in relation to individual theorems, such as the relationship between attraction and repulsion force, even though the reasons for Lambert and Kant’s deviation from Newton’s theory of gravity also differ. For in its main features the transcendental metaphysics of Kant’s nature is substantially different from the mathematical methodology of Lambert’s theory of nature. In addition, Lambert stuck throughout his life to a theonomous natural teleology in the succession of Wolff, which was fundamentally made impossible by the Critique of Pure Reason: because the wise “intention of the creator”, which Lambert’s empirical-rationalistic cosmology could not and did not want to do without, could no longer be referred to in a rational context according to the Critique of Pure Reason. Even if Lambert certainly had moments of the Kantian theory of matter or — as Kant himself admitted — elements of the spatial theory of the first Critique, there is no way from his mathematisation of metaphysics and his natural teleology to the fundamental innovation of the Metaphysical Foundations. (shrink)