This slippage in meaning isn’t a unique case of politics outgrowing a speaker’s intentions, but a reflection of the fundamental structure of language itself. As philosophers since Plato have noted, language does not and cannot stay confined to one object or situation; to speak of something is, to some extent, to speak of it in general. Even a sentence as simple as “the sky is blue” already depends on a broader concept—blueness—that goes beyond the sky itself. Understanding the sentence therefore entails recognizing the sky as part of a larger category, creating an inherent comparison between it and all other blue things. So too when we call something a genocide; the word itself would be meaningless if it did not categorize historical events within a general framework of atrocity.

Philosopher Jacques Derrida called this essential feature of language “iterability”: for a word or phrase to be meaningful at all, it must be able to be grafted onto new contexts. As he writes in “Signature Event Context,” any piece of language “can break with every given context, engendering an infinity of new contexts.” This is how “never again” was able to travel from Kahane’s manifesto to an anti-Zionist rallying cry used by Jewish Voice for Peace. To understand a phrase is to be able to replicate and reinterpret it, so to understand the meaning of “never again” is to immediately call to mind other instances of genocidal violence—Rwanda, Bosnia, Darfur, and, inevitably, Gaza.