An often overlooked aspect of the interpretive theory of intentionalism is the extent to which it relies on the notion of counterfactual intention. Intentionalism is the thesis that the interpretive meaning of legal texts is determined by the author’s intentions at the time of writing.Examples of writers who endorse different kinds of intentionalism for different reasons are the following: Alexander (1995); Goldsworthy (1997); MARMOR (1992), esp. p. 176ff; and Raz (1996). Authors’ intentions, however, like all psychological states, are often inchoate, conflicting, or inaccessible to interpreters due to conflicting or inadequate evidence. In such cases, intentionalists resort to counterfactual reasoning, that is, reasoning about the intentions that the author would have had under more optimal conditions than those that actually obtained. What is usually not noted is that counterfactuals are vague, and therefore that the resort to counterfactual intentions brings with it a significant risk of indeterminacy.Some of the ideas in this paper were first developed in STOLJAR (1998).