The “Necessity” Fallacy in Kantian Ethics

A common strategy in ethical argumentation tries to derive ethical obligations from the rational necessity of not acting against certain “necessary” conditions for satisfying some good end. This strategy is very often fallacious, and works by equivocating over what counts as a “necessary” condition. Very often, what is counted as a necessary condition is not logically necessary for the end in question, but is at most related to it by affecting the probability of the end’s satisfaction. If other conditions affecting the probability of satisfying this ends are then discounted as merely “instrumental” or “probabilistic”, this strategy has the function of hypocritically privileging some of the arguer’s preferred values over others. We should instead recognize that nearly all conditions affecting the probability of satisfying some good end borrow some value from the value of the end, in proportion to how much they tend to affect its probability of satisfaction. The fallacy tends to support rigid deontological norms; once we abandon it, many arguments against consequentialism are revealed merely as special pleading. Many ethical arguments use this fallacy, but I focus here on its use by Immanuel Kant.