As with any scientific revolution, quantum mechanics entailed a profound revision of our fundamental epistemological concepts and also of our worldview as a whole. This was the case for the concepts of causality and reality. Around these concepts, there arose in the third decade of the last century a heated debate in which almost all the scientists and philosophers of the time took part and which in a certain sense is still going on today. The Author provides a reconstruction of the various different positions, from the "conservative" attempt to defend determinism to the most radical stochastic positions, and singles out in Ernst Cassirer’s solution the most convincing approach.
Keywords: Causality, reality, determinism, indeterminism, probability, quantum mechanics, hidden variables or parameters, epistemology