Journal Article


Roy Sorensen

in The British Journal for the Philosophy of Science

Published on behalf of British Society for the Philosophy of Science

Volume 54, issue 1, pages 93-101
Published in print March 2003 | ISSN: 0007-0882
Published online March 2003 | e-ISSN: 1464-3537 | DOI:

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A para‐reflection is a privational phenomenon that is often mistaken for 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. Para‐refractions display parallel obedience to the laws governing refraction. 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. I conclude that this kind of subtle treatment of negative things needs to be extended to optics.

1 The invisible red herring

2 Mind‐independent privations

3 Para‐reflections are mind‐independent

4 Parasitical entities

5 Para‐refractions and shadows

6 How science has coped with privations

Journal Article.  0 words. 

Subjects: Philosophy of Science ; Science and Mathematics

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