 The argument is a paradox because apparently impeccable reasoning from apparently impeccable premises yields a falsehood. The argument can be run equally in the opposite direction, from the premise that one million grains make a heap: if one million grains make a heap, then one million less one grain make a heap; and if one million less one grain make a heap, then one million less two grains make a heap; etc. It follows, absurdly, that even a single grain makes a heap. Thus soritical reasoning appears to show both that no number of grains make a heap and that any number of grains make a heap.