Chalmers (2012) argues that the functional conception neglects important features of computation. As he notes, computational models usually describe more than just input-output relations. They describe intermediate steps through which inputs are transformed into outputs. These intermediate steps, which Marr consigns to the “algorithmic” level, figure prominently in computational models offered by logicians and computer scientists. Restricting the term “computation” to input-output description does not capture standard computational practice.