The principle that things are not identical to themselves over time, challenging Aristotle's law of identity (A = A). The law of non-identity observes that everything changes constantly—the you of this moment is not the you of a moment ago, a river is never the same water twice, and your favorite coffee mug, after years of use, is physically, chemically, and sentimentally different from the one you bought. Identity is an illusion we impose on flux. The law of non-identity explains why you can't step in the same river twice, why returning to a childhood home feels strange (it's not the same home, and you're not the same you), and why "I'm just not myself today" is literally true every day.
Example: "She invoked the law of non-identity when her partner said 'you've changed.' 'Of course I have,' she said. 'The law of non-identity says I'm not the same person I was yesterday, let alone five years ago. If I were identical to my past self, that would be the problem.' Her partner missed the person she used to be. She was busy becoming the person she was going to be."
by Dumu The Void February 15, 2026
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