The Copenhagen interpretation presumes the legitimacy of quantum superpositions, attaches ``the probabilistic nature'' to quantum mechanics, brings observers into axioms of the theory, and claims that quantum mechanics is already a complete theory. Einstein disagreed with this interpretation; he argued against the legitimacy of quantum superpositions, worried about observers in the axioms, and considered quantum mechanics incomplete. Inspired by Einstein, Bell and his followers intended to complete quantum mechanics within the framework of local realism. They derived Bell inequalities, tested them by experiments, and proved Bell's theorem to interpret the experimental results. Regrettably, the experimental results are misinterpreted. This article introduces a new principle, the general principle of measurements, and provides its mathematical proof. Based on this principle, quantum mechanics can be completed within the framework of local realism by using disjunction (``or'') as the logical relation between orthonormal vectors spanning any given Hilbert space while keeping its general definition unchanged. Probabilistic predictions given by the completed theory and the current theory are exactly the same. Furthermore, by eliminating observers from the axioms and precluding inexplicable collapses of wave-functions, the completed theory alleviates much difficulty in understanding quantum mechanics and is intuitively comprehensible. In conclusion, Einstein's local-realist world-view is correct.
I distinguish two senses in which one can take a given physical theory to be `complete'. On the first, a complete physical theory is one that, in principle, completely describes physical reality. On the second, a complete physical theory is one that provides all of the conceptual resources one needs to describe any (in general probabilistic) physical phenomenon to any level of detail one likes, in principle. I argue that while the (neo-)Everettian approach to interpreting quantum mechanics aims to show that it is complete in the first sense, the (neo-)Bohrian approach begins from an understanding of quantum mechanics as being complete in the second sense. I then discuss some of the essential differences between how classical and quantum theory describe phenomena, and the way in which the quantum description can be thought of as a ``natural generalisation'' (to use Bohr's phrase) of the classical description. Finally, I elaborate upon the two visions of physics from which one can motivate the first and the second sense of completeness, respectively: \emph{metaphysical realism}, on the one hand, and what I will call \emph{methodological realism}, on the other -- and discuss what one can say about the significance of the differences between quantum and classical description from each of these points of view. I suggest that there is a sense in which the views of (neo-)Everett and the views of (neo-)Bohr can be understood to be mutually supporting positions, from their respective perspectives, even though they are diametrically opposed.
In the Einstein-Bohr debate, Einstein considered quantum mechanics incomplete and disagreed with Born’s probabilistic interpretation of wave-functions. Observers in the axioms of quantum mechanics also bothered Einstein. Inspired by Einstein, Bell and his followers intended to complete quantum mechanics within the framework of local realism. Regrettably, the deterministic correlation between distant components of a separable system in Einstein’s local-realist description of the world is mistaken for non-locality in the world described by Bell’s theorem, leading to incorrect interpretations of experimental results obtained by testing Bell inequalities. This article introduces a new principle, the general principle of measurements, which is proved as a mathematical theorem and allows quantum mechanics to be completed within the framework of local realism while keeping the formal axiomatic definition of a general Hilbert space unchanged. The completed theory can provide the same probabilistic predictions of empirical results as those provided by the current theory. Using disjunction (“or”) as the logical relation between superposed orthonormal vectors, the completed theory precludes observers in the axioms of the current theory and inexplicable collapses of wave-functions, thus it is intuitively comprehensible and alleviates much difficulty in understanding quantum mechanics. Among various world views, Einstein’s local-realist world view is correct.