"If language is to be a means of communication there must be agreement not only in definitions but also (queer as this may sound) in judgments." (Part I, section 242)

How would we communicate with someone who genuinely doubted that the world existed five minutes ago? We could not discuss history, memory, or current affairs. our very conception of the significance of our lives would be incomprehensible to this person. Further, there is no evidence we could convince this person otherwise. The ordinary statements of everyday life—the kinds of statements that we can claim to know, doubt, justify, and explain—are not founded upon a bedrock of certainty. Rather, they are founded upon a number of judgments that are not open to question. We are able to debate questions in history because we are not able to debate the question of whether the world has existed for more than five minutes. In order to communicate fruitfully, we must agree in these judgments. This agreement is not explicit, nor even tacit. Such agreement reflects our shared forms of life.

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