Whatever it is that makes people worthy of moral consideration, these things don’t all appear in one magic moment. Without a magic moment to believe in, pro-choicers simply have to draw the line somewhere, while acknowledging that the line they’ve drawn is somewhat arbitrary. There may be no better place to draw the abortion line than where we currently draw it. But if there are good arguments, based on common currency, for drawing the line elsewhere, then deep pragmatists should listen.