structural:scholar_edition, linguistic:translation
Opposition to the Stoics

Galen was well known for his advancements in medicine and the circulatory system, but he was also concerned with philosophy. He developed his own tripartite soul model following the examples of Plato; some scholars refer to him as a Platonist. Galen developed a theory of personality based on his understanding of fluid circulation in humans, and he believed that there was a physiological basis for mental disorders. Galen connected many of his theories to the pneuma and he opposed the Stoics ' definition of and use of the pneuma.

The Stoics, according to Galen, failed to give a credible answer for the localization of functions of the psyche, or the mind. Through his use of medicine, he was convinced that he came up with a better answer, the brain. The Stoics only recognized the soul as having one part, which was the rational soul and they claimed it would be found in the heart. Galen, following Plato's idea, came up with two more parts to the soul.

Galen also rejected Stoic propositional logic and instead embraced a hypothetical syllogistic which was strongly influenced by the Peripatetics and based on elements of Aristotelian logic.