The most elementary empirical truth associated with any experiment involving light (electromagnetic radiation) propagation is the distinction between the source (region of cause) and the detector (region of effect), i.e. ``cause/effect'' distinction, based on which one can speak of ``distance between source and detector'', ``propagation from source to detector'' and, therefore, ``action at a distance'', ``velocity of propagation''. According to EPR's completeness condition, ``cause/effect'' distinction should be taken into account in a theory that is supposed to provide explanations for such an experiment, the simplest one being the Hertz experiment. Then, in principle, one can decide whether ``cause before effect'' or ``cause after effect'' i.e. the logic of causality remains decidable. I show that, working with Maxwell's equations and ``cause/effect'' distinction to explain Hertz experiment, Poynting's theorem is unprovable. It is provable if and only if ``cause/effect'' distinction is erased by choice through an act of free will, but the logic of causality becomes undecidable. The current theoretical foundation behind the hypothesis of `light propagation' comes into question as theoretical optics is founded upon Maxwell's equations and Poynting's theorem. A revisit to the foundations of electrodynamics, with an emphasis on the interplay among logic, language and operation, seems necessary and motivated.