Abstract
Whether understanding-why is reducible to propositional knowledge of cause is among the most debated issues in the philosophy of understanding. Many anti-reductionists consider that understanding comprises a set of cognitive abilities and that it is different from having propositional knowledge. In contrast, one strategy that reductionists adopt is showing that such abilities constituting understanding are also required for propositional knowledge. This paper aims to show that this type of strategy fails because it confuses abilities prerequired for propositional knowledge with ones that are constituents of understanding. Undeniably, an agent is sometimes required to answer some type of ‘What-if’ questions in order to have propositional knowledge. However, this only shows that the agent is required to understand concepts that appear in a proposition in order to know the proposition. It is thus important to examine the “process”—how the agent has a belief when judging whether the agent has propositional knowledge—while it is important to examine the “achievement” when judging whether the agent understands the phenomenon at issue.