 William Bechtel and Robert McCauley (1999) develop a version of “heuristic” mind-brain identity theory (HIT) and defend it explicitly against multiple realizability. HIT insists that identity claims in science typically are hypotheses adopted in the course of empirical investigations, which serve to guide subsequent research. They are not conclusions reached after empirical research has been conducted. Concerning the multiple realizability of psychological on brain (physical) states, cognitive neuroscience’s heuristic identity claims assert type-commonalities in comparative studies across species, not type-differences. Bechtel and McCauley illustrate their hypothesis with case studies: Brodmann’s early twentieth century work mapping the brain into functionally relevant areas; Ferrier’s late-nineteenth century work employing electrical stimulation to cortex; and more recent detailed maps of visual processing regions in the primate brain. All of these landmark functional anatomical studies used multiple species. As Bechtel and McCauley remind us,