Abstract

The paper considers Ernst' Cassirer's standpoint with reference to Euclidean geometry and the complementarity principle of quantum theory, interpreted as a choice between a causal description and a space — time description. The acceptance of the complementarity principle by Cassirer not only lands him off the Kantian path slightly, but it also leads him to some contradictions and incompatibilities within his own system of thought. 1. Accepting complementarity, Cassirer cannot still hold that there is an infinite hierarchy of objective levels as he does towards the end of hisDeterminismus; and 2. accepting complementarity, Cassirer cannot still hold on to the observability principle of Leibniz.