To the Editor: The concept of mental first-person experiences is not as irrevocably grounded as Dr. Kendler suggested. He maintained the solipsism of the individual, ignoring Wittgenstein’s concept of language as a tool that individuals use to interact with the environment (1). Wittgenstein noted that language and action produced by thought are a means of producing an empathic relationship between the first and second person. Psychiatrically, this empathic interaction results in a phenomenological psychopathology, a process that is vital to the practice of psychiatry.

Dr. Kendler avoided the basic problem psychiatry faces, which is, what is a mental state? In so doing, he leaves any potential framework hanging in limbo, maintaining the gulf between the mind and the brain. Dr. Kendler did not mention intentionality, which Brentano noted in 1874 (2) as characterizing "the mental." The concept of intentional causality associated with meaning and belief and the nonintentional associated with chemical and physical law-like relationships can provide an acceptable explanation of mental function. The mind can then be explained in a framework of dynamic intentional and nonintentional causal processes in which top-down and bottom-up causality can explain all mental functions and dysfunctions, from molecular interactions to the higher-level intentional processes that produce consciousness.