Background
Nelson, Leonard was born on July 11, 1883 in Berlin. *29 November 1927, Göttingen, Germany.
Nelson, Leonard was born on July 11, 1883 in Berlin. *29 November 1927, Göttingen, Germany.
Nelson was the founder of the so-called ‘neoFriesian’ school. The members of this school based their approach on the thought of Jakob Friedrich Fries (1773-1843), who himself had advocated a positivistic philosophy that followed Kant, Jacobi, Schleiermacher and Ernst Platner. Nelson saw Fries as having solved Hume’s problem, and thus as having perfected Kant's philosophy. His attempt to make Reinhold relevant again for the philosophical discussion of the day therefore also meant a return to Kant. Nelson believed that ‘every important dispute in philosophy is a dispute about principles’. He argued that Kantian epistemology cannot provide sufficient conditions for the objective validity of our knowledge. It can only supply necessary conditions for it, and it must thus be supplemented by another approach. Nelson called this approach ‘deduction’, and he understood by it a descriptive psychological theory of reason. Arguing that our perceptual judgements are not only based on logical principles, but also on sensations that are immediately evident, he claimed that it was these sensations that are most basic for determining the objective validity of judgements. Since epistemology was an attempt to find a criterion for the objective validity of judgements that itself constituted a judgement, it was, he felt, an enterprise doomed from the start. Metaphysics, though not based on psychological description, must be preceded by it. The psychological deduction does not prove the basic philosophical principles, but it determines what they are. Indeed he argued that in so far as these principles are truly basic they cannot possible be proved. Just as Nelson's metaphysics proceeded by descriptive analysis, so his moral philosophy started from psychological observation. Nelson argued that our moral feeling proves that we have duties. The content of these duties was determined through another ‘deduction’, which was meant to determine ‘the interests of pure practical reason’. He found two principles, namely the categorical imperative, or the principle of balanced consideration of all interests, which stated that one should never ‘act in such a way that you could not agree to your way of acting if the interests of those affected were also your own’, and the principle of rational self-determination that states that everyone should pursue his own ends independently and in accordance with the true, the good, and the beautiful. He thought that there was no tension between these two principles, if the true interests of humanity were understood. Nelson’s theory, like that of Fries before him, was often accused of ‘psychologism’, and it remained rather controversial. However, it is not always clear whether these criticisms were motivated by philosophical or by political reasons, for Nelson was also very active in the Social Democratic movement. He not only openly advocated socialism as the best way to transform the unfair political system of Germany into a fair and just society, but he founded such political organizations as the ‘Internationale Sozialistische Kampfbund’. His demands for reform extended to animal rights. Indeed he argued that the slaughter of animals constituted a form of exploitation that stood in the way of the development of a society without exploitation.