His criticism of Stout turns on the difficulty of giving any empirical meaning to such notions as the mind or the subject he quotes from Stout the sentence: The most important drawback is that the mind, in watching its own workings, must necessarily have its attention divided between two objects, and he concludes: Without question, Stout is bringing in here illicitly the concept of a single observer, and his introspection does not provide for the observation of this observer; for the process observed and the observer are distinct (p.