Quantum mechanics in general only makes probabilistic predictions. Einstein, Podolsky, and Rosen (EPR) were puzzled by this because it would lead to EPR-non-locality. They believed that quantum mechanics must be incomplete, as they tried to argue for in their seminal paper on the completeness of quantum mechanical descriptions. Later, de Broglie and Bohm showed that causal theories extending quantum mechanics like EPR sought for exist (even though manifestly non-local). Although such theories are possible, it remains open if extensions of quantum mechanics would also have enhanced predictive power. In other words, is quantum mechanics empirically complete? Many quantum features suggest an affirmative answer. I will discuss some of them and show an intermediate result towards proof of the theory’s empirical completeness.