Ancient Theories

Abstract

The ancient Greek and Roman philosophers developed the ingredients of most of the conceptions about the soul which have later become influential in the history of philosophy. Plato’s contributions to psychology include highly influential arguments for dualism, whereas Aristotle emphasises the functionalist idea of the soul as the form of a living body. However, both philosophers are far from unambiguous in their theories of the soul, and their importance is by no means reducible to these basic ideas.

Among the Hellenistic philosophers, there existed a remarkable consensus about some features in the nature of the soul, even though their other philosophical views were quite divergent. The Epicureans, the Stoics, and many Hellenistic physicians endorsed dualist theories of the soul in the sense that the soul and the body are distinct from each other as substances. Despite this distinction, many Hellenistic philosophers also held that the souls are material or corporeal. They share the belief that something can be said to exist only if it is spatially extended, three-dimensional, and capable of acting or being acted upon. Therefore, the idea of a purely immaterial soul is rejected. Souls have matter which is, however, different from the matter of inanimate, or ‘non-souled’, bodies.

The later part of the ancient philosophical tradition saw a renewed interest in Plato and Aristotle. The first major commentator of Aristotle, Alexander of Aphrodisias (third century), developed the Aristotelian position in great detail. The most important development was the interpretation he gave to De anima III.5, and the introduction of the so-called agent intellect. An influential discussion of this doctrine is in a small treatise on the intellect which was translated into Latin and known in the Arabic philosophical tradition. The Platonic doctrines became more and more influential towards the end of the ancient tradition. Plotinus (204/5–270) and the Neo-Platonists foremost incorporated the view which Plato explicated in the Phaedo. Plotinus in turn had a significant influence on the first major Christian philosopher, Augustine (354–430). In De trinitate, Augustine develops arguments for the incorporeality of the soul, which in turn had an enormous influence on philosophy of mind in a Platonic tradition throughout the Middle Ages and into early modern times.