Midwest Studies in Philosophy 28, 75-90, 2014. Preprint PDF.
The problem of imperceptible effects arises because very small changes are not perceived, even if many of these small changes together are. If the normatively relevant consequences of an action, holding all other actions fixed, cannot be perceived, we are challenged to explain what makes the action wrong. I argue that an action cannot only be wrong because of its immediate effects, it can also be wrong because it can cause an effect together with other actions. More precisely, individuals performing these actions do wrong because they ignore the risk that their action, even though it cannot be perceived while holding all other actions fixed, may well be perceived together with other actions if we do not hold everything else fixed.