 Slippery slope arguments express the worry that permitting a certain practice may place us on a slippery slope to a dangerous or otherwise unacceptable outcome. Several commentators have argued that accepting or allowing cloning research is the first step that would place us on a slippery slope to reproductive cloning. As Leon Kass (1998, 702) has put it: “once the genies put the cloned embryos into the bottles, who can strictly control where they go?”