Fine-tuning the impairment argument

Perry Hendricks' original impairment argument for the immorality of abortion is based on the impairment principle: if impairing an organism to some degree is immoral, then ceteris paribus, impairing it to a higher degree is also immoral. Since abortion impairs a fetus to a higher degree than fetal alcohol syndrome (FAS) and giving a fetus FAS is immoral, it follows that abortion is immoral. Critics have argued that the ceteris paribus is not met for FAS and abortion, and so we proposed the modified impairment principle (MIP) to avoid these difficulties. Dustin Crummett has responded, arguing that MIP is open to various counterexamples which show it to be false. He also shows that MIP can generate moral dilemmas. Here, we propose a modification to MIP that resolves the issues Crummett raises. Additionally, Alex Gillham has criticised our appropriation of Don Marquis' 'future like ours' reasoning about the wrongness of impairment. We show that his objections have minimal implications for our argument.