In
critical theory, a binary opposition (also binary system) is a pair of theoretical opposites. In
structuralism, it is seen as a fundamental organizer of human philosophy, culture, and language. In
post-structuralism, it is seen as one of several influential characteristics or tendencies of Western and Western-derived thought, and that typically, one of the two opposites assumes a role of dominance over the other. The categorization of binary oppositions is "often value-laden and ethnocentric", with an illusory
order and superficial meaning.
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If you use "binary thinking," you are a person who sees no gray, no fuzziness between your categories.  Everything is black or white.