Criteria of mind

James (1890) observed that an outside observer, unable to perceive accompanying consciousness, might be unable to tell automatic acts from willed ones.¹ If the criterion of mind is the choice of proper means to an end, he argued, all acts seem intelligent, because appropriateness marks them all alike.¹ He reported two opposed theories. Some authors gave even the lowest reflexes an accompanying feeling. Others held that appropriateness owes nothing to consciousness.¹ Loeb (1912) described the same criterion in use. Some authors called a reaction conscious when an animal or organ acted as a rational human would, and consciousness had even been ascribed to the spinal cord.⁷

Washburn (1908) reported that the criterion most often applied was a change in behaviour that shows the result of previous individual experience.⁴ She quoted Romanes asking whether an organism learns to make new adjustments from its own experience. She also quoted Loeb, who named associative memory as the elemental component of all psychic phenomena.⁴ She described an opposite tendency among physiologists, who made biological concepts suffice where possible and assumed consciousness only when unavoidable.⁵ In her account, Loeb in 1890 treated animal responses as tropisms like those of plants to light and gravity. Bethe in 1898 explained ants and bees by reflexes without consciousness. She called this a revival of the Cartesian doctrine in altered form.⁵

Jennings (1906) argued that objective evidence can demonstrate neither the presence nor the absence of consciousness, since consciousness cannot be perceived objectively.³ He therefore confined his volume to the objective processes of behaviour.³ Verworn (1899) rejected the usual direction of explanation. He held that all attempts to explain the psychical by the physical must fail, and that the task is to reduce physical phenomena to psychical elements.² Driesch (1908) took another course. He held that natural science may not mix psychical elements with phenomena already objectified as physical, and he proposed the psychoid, a kind of entelechy, as a natural correlate.⁶ Loeb, in contrast, looked for elementary physiological processes underlying consciousness.⁷

Levin (2022) quotes an earlier author who wrote that terms pointing to psychical analogies were used again and again, and were meant as more than poetical metaphor.⁸ Levin (2025) argues that the categorical line between molecular pathways and cognitive content, such as memories and world models, is dissolved.⁹ On this view, biomedicine becomes communication with an unconventional agent, and the relation of mind and matter is a practical matter as well as a philosophical one.⁹