  We argue that Anton Zeilinger's "foundational conceptual principle" for
quantum mechanics according to which an elementary system carries one bit of
information is an idealistic principle, which should be replaced by a realistic
principle of contextuality. Specific properties of quantum systems are a
consequence of impossibility to speak about them without reference to the tools
of their observation (identification) and, consequently, context in which these
tools are applied. In particular, the assumption of non-locality is not
required to explain quantum correlation. Correlated quantum events are related
with each other in a causal way. But this is not classical, but quantum
causality expressed by an entangled wave function. This or that particular
correlation does not arise in measurement; in measurement it is identified in
context. In contrast to Zeilinger's proposed principle of quantization of
information, the principle of contextuality explains it realistically.
