 Can the economic theory of rationality accommodate this understanding of normativity? Arguably, the ad hoc assumption that the agent incurs a cost when she fails to comply with a legal duty captures this idea. This ad hoc cost implies that ordinary costs and benefits must be sufficiently large to outweigh the cost imposed by the prohibition. But this approach fails to capture some of the potential subtleties of an exclusionary reason as the obligation may not depend on the size of the costs (or force of the reason) but on the nature of it. An obligation may exclude some types of costs, no matter how large, but not exclude other types of costs, no matter how small. 