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The unexpected hanging paradox or hangman paradox is a paradox about a person's expectations about the timing of a future event that he is told will occur at an unexpected time. The paradox is variously applied to a prisoner's hanging, or a surprise school test. Despite significant academic interest, there is no consensus on its precise nature and consequently a final correct resolution has not yet been established. One approach, offered by the logical school of thought, suggests that the problem arises in a self-contradictory self-referencing statement at the heart of the judge's sentence. Another approach, offered by the epistemological school of thought, suggests the unexpected hanging paradox is an example of an ''epistemic paradox'' because it turns on our concept of ''knowledge''.〔(Stanford Encyclopedia discussion of hanging paradox together with other epistemic paradoxes )〕 Even though it is apparently simple, the paradox's underlying complexities have even led to it being called a "significant problem" for philosophy. ==Description of the paradox== The paradox has been described as follows:〔(【引用サイトリンク】title=Unexpected Hanging Paradox )〕 Other versions of the paradox replace the death sentence with a surprise fire drill, examination, pop quiz, or a lion behind a door.〔 The informal nature of everyday language allows for multiple interpretations of the paradox. In the extreme case, a prisoner who is paranoid might feel certain in his knowledge that the executioner will arrive at noon on Monday, then certain that he will come on Tuesday and so forth, thus ensuring that every day he is not hanged really is a "surprise" to him, but that the day of his hanging he was indeed expecting to be hanged. But even without adding this element to the story, the vagueness of the account prohibits one from being objectively clear about which formalization truly captures its essence. There has been considerable debate between the logical school, which uses mathematical language, and the epistemological school, which employs concepts such as knowledge, belief and memory, over which formulation is correct. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Unexpected hanging paradox」の詳細全文を読む スポンサード リンク
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