 White (1982) and Fodor (1987) have offered a rather different, and highly influential, way of thinking about narrow content. This conception focuses on what narrow contents are supposed to accomplish. A narrow content is supposed to be something that Oscar and Twin Oscar share, and by virtue of which Oscar believes that water is wet and Twin Oscar believes that XYZ is wet. Similarly, it should be something that Art in his actual environment shares with Art in his envisioned counterfactual environment, and by virtue of which he believes, in his actual environment, that he has arthritis in his thigh, and believes, in the counterfactual environment, that he has a different and broader disease in his thigh. So one approach to narrow content is simply to declare that a narrow content is something that, given a particular environment, determines a particular broad content. Block (1991) calls this the “mapping theory,” since on this account a narrow content maps environments into broad contents.