As others have mentioned, it’s basically a virtue argument: are you the sort of person who, given a nearly equal choice, would avoid consuming slaughtered animals (vegetarian) or all products of animal farming (vegan). The exact utility is not easy to calculate, and deontology is virtue ethics or utilitarianism codified into easy-to-digest (hah) rules, anyway.
As others have mentioned, it’s basically a virtue argument: are you the sort of person who, given a nearly equal choice, would avoid consuming slaughtered animals (vegetarian) or all products of animal farming (vegan). The exact utility is not easy to calculate, and deontology is virtue ethics or utilitarianism codified into easy-to-digest (hah) rules, anyway.