In a detailed monograph, the author studies speech disorders in detail. First, a historical outline of the development of the doctrine of speech disorders from Dieffenbach's unfortunate speech, which considered the cause of stuttering to be a peripheral spasm of the tongue, to the classic work of Kussmau, which played a huge role in Logopathology, and to the current state of the issue. Under the name of Logology, the author understands a doctrine that embraces the physiology of speech and psycho-biological research, as the development of a childs speech and its relationship to his intellect, with special attention to the psycho-physiological foundations of speech development, psychology and philosophy of speech.