Suppose that, for reasons of animal welfare, it would be better if everyone stopped eating chicken. Does it follow that you should stop eating chicken? Proponents of the “inefficacy objection” argue that, due to the scale and complexity of markets, the expected effects of your chicken purchases are negligible. So the expected effects of eating chicken do not make it wrong.
We argue that this objection does not succeed, in two steps. First, empirical data about chicken production tells us that the expected effects of consuming *many* chickens are not negligible. Second, this implies that the expected effect of consuming one chicken is ordinarily not negligible. *Parity* between your purchase and other counterfactual purchases and *uncertainty* about others’ consumption behavior each tend to pull the expected effect of a single purchase toward the average large scale effect. While some purchases do have negligible expected effects, many do not.