I'm pro genetic engineering, but I have to present a strong case for squarely the exact opposite. So what are some compelling arguments against it? Take what would be the most uncontroversial usecase--correcting a single gene disorder, something like Tay Sachs or Huntington's. The slippery slope towards eugenics argument as well as the off-target effects are pretty standard at this point. You could make an appeal to evolution and suggest that nearly all traits are pleiotropic, and the removal of one gene to correct a negative phenotype would almost certainly have unpredicted effects. Are there any clever justifications I'm missing? It's hard to argue against removal of a single gene that has no upside and is fatal for the carrier. Perhaps embryo selection would be an alternative, but this would not work in the rare instance where both parents have homozygous alleles.