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Let's say that two individuals are epistemic counterparts iff they happen to be in precisely the same (non-factive) mental states. If one has a veridical experience, her counterparts will undergo a subjectively indistinguishable conscious experience. If she remembers something, her counterparts will seem to recall the same event or fact. If she knows something to be true, her counterparts will believe it to be true. Counterparts always find the same things intuitive. Any difference between those who know a great deal about the external world and their systematically deceived counterparts is a difference the deceived counterparts could never appreciate.
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Clayton Littlejohn (2009) studied this question.
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