Getting contextual and nonlocal elements‐of‐reality the easy way

What if Einstein, Podolsky, and Rosen were right that quantum mechanics is incomplete, and there do exist ‘‘elements‐of‐reality’’ corresponding to all observables whether or not they are compatible? The implications are surprising. Not only must the values of these elements‐of‐reality depend upon what measurements are actually performed on the system, but also upon measurements performed at spacelike separation from it! The former dependence has been dubbed ‘‘contextualism,’’ and the latter ‘‘nonlocality.’’ It is important for students to understand the necessity of these two features, if only to reinforce the point that a straightforward classical recasting of quantum theory in terms of pre‐existing measurement independent elements‐of‐reality is not feasible. Unfortunately the argument for contextualism, in particular, is daunting due to its reliance on an elaborate geometrical argument. I aim here to minimize the geometry needed to argue for contextualism by using some ideas inspired by the original arguments of Bell and of Kochen and Specker. Using similar methods, I simplify the closely related geometrical argument for nonlocality due to Heywood and Redhead and to Stairs.