 This outcome suggests that not only careful empirical work, but also difficult conceptual work, is required for determining the scope and degree of introspection’s reliability—solving what Goldman aptly terms “the problem of calibration” (Goldman 2004: 14). Some targets of introspection, such as sensations, can be identified only through introspection itself: third-personal methods (for instance, identifying pain via a brain scan) depend on prior correlations between third-personal and introspective data. Goldman notes that, for this reason, we can fix the range of introspective reliability only by using introspection and evaluating its results for internal coherence and for consistency with other sources. But since there is no clear consensus as to how to evaluate the results of introspection, or how to weigh its results against other sources of evidence about mental states, the problem of calibration is especially thorny and complex as it relates to introspection. Spener (2015) proposes that we calibrate introspection by reference to abilities that we could not possess unless introspection were reliable (relative to certain circumstances, and about certain states). For example, our ability to focus binoculars on a distant object suggests that introspection is reliable in identifying when things look blurry.