A para-reflection is a privational phenomenon that is often mistaken as a reflection. You have seen them as the “reflection” of your pupil in the mirror. Your iris reflects light in the standard way but your pupil absorbs all but a negligible amount of light (as do other dark things such as coal and black velvet). Para-reflections work by contrast. Since they are parasitic on their host reflections, para-reflections are relational and dependent in a way that reflections are not. Nevertheless, para-reflections obey nearly all the laws of reflection with exquisite fidelity. Physicists and psychologists who study optics have neglected these everyday phenomena. Happily, physicists have been attentive and insightful about other privational phenomena such as vacuums and cold spots. This kind of subtle treatment of negative things needs to be extended to optics.
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