Causal inference in process tracing recently gained interest in the literature. Large parts of the debate focus on van Evera''s typology constituted on the dimensions of uniqueness and certitude. My paper specifically focuses on the dimension of uniqueness. According to one line of reasoning, the confirmation of a unique observable implication is argued to confirm one hypothesis and disconfirm rival hypotheses. I argue and show by empirical examples that this interpretation of uniqueness is ill-conceived. It conflates the implications of the presence and absence of confirming empirical evidence for causal inference in process tracing. Finally, a proposal is made for improving the typology in order to get a comprehensive picture of hypothesis tests in process tracing.
