 Skyrms’ (1993) “diachronic Dutch book” argument for conditionalisation can be read in this way. The agent is assumed to have EU preferences and to take a sophisticated (backwards reasoning) approach to sequential decision problems. Skyrms shows that any such agent who plans to learn in a manner at odds with conditionalisation will make self-defeating choices in some specially contrived sequential decision situations. A conditionalising agent, by contrast, will never make choices that are self-defeating in this way. The kind of “self-defeating choices” at issue here are ones that yield a sure loss. That is, the agent chooses a strategy that is surely worse, by her own lights, than another strategy that she might otherwise have chosen, if only her learning rule was such that she would choose differently at one or more future decision nodes.