The Tortoise asks Achilles whether the conclusion logically follows from the premises, and Achilles grants that it obviously does. The Tortoise then asks Achilles whether there might be a reader of Euclid who grants that the argument is "logically valid", as a "sequence", while denying that "A" and "B" are true. Achilles accepts that such a reader might exist (that is, a reader who denies the premises), and that he would hold that "if" "A" and "B" are true, "then" "Z" must be true, while not yet accepting that "A" and "B" are true.