Philosophy Professor Dr. Joel MacClellan defends axiological extensionalism in a chapter of forthcoming book, Ethical Diets and Animal Ethics — Beyond Extensionism, which will be part of the Springer International Library of Environmental, Agricultural and Food Ethics.

The paper offers a defense of axiological extensionism both in its own right and in response to contemporary critics. Axiological extensionism takes a morally valuable trait already recognized in us and argues that we should recognize the value of that trait in other entities, such as non-human animals, who have been historically marginalized. First, MacClellan distinguishes axiological extensionism from other forms of ethical extensionism, such as the extension of traditional moral theories to new areas of inquiry. Next, he lays bare the underlying logical form of axiological extensionism, arguing that such arguments are valid, and when supplied with plausible and substantive moral premises, are also sound. As evidence of their pervasiveness and historical efficacy, he then traces the history of axiological extensionist arguments in late 18th century English authors’ calls for progressive expansions of the human moral community to historically marginalized groups. Lastly, he defends axiological extensionism from several criticisms in the recent literature, including (1) the claim from some environmental ethicists that it contains too austere a conception of moral value (2), the objection of some feminist ethicists that in emphasizing similarity, it fails to account for the moral significance of difference, (3) some disability theorists’ criticism that axiological extension to nonhuman animals is offensive to the disabled and their loved ones, and (4) the objection by animal rights theorists that axiological extensionism has failed to adequately improve the treatment of non-human animals. While something is to be gained from each criticism, he argues that these criticisms ultimately fail and that axiological extensionism remains a compelling view.