Which is not an appropriate thesis for an essay comparing the safety of artificial sweeteners? although both authors carefully document their sources and present ample evidence to support their claims, the statistics and expert testimony that keitel cites is ultimately more convincing. blackwell’s reliance on personal stories and dated reports makes his argument less convincing than keitel’s. keitel argues that artificial sweeteners are safe, and blackwell asserts they are not. keitel’s use of statistics and government reports makes her argument that artificial sweeteners are safe more convincing that blackwell’s assertion that they are not.