HEGEMONIKON is ‘internal rational ruler’. This name is in use among many philosophers of Ancient Greece to address the intellectual governing part of the soul. In particular, Stoics distinguish the <hegemonikon> from the senses. In fact, the thinkers of that philosophical movement identify the ‘control room’ of the soul as the <hegemonikon>. So it is the <hegemonikon> which receives and assembles the impressions of <phantasiai> (imagination) delivered by the senses.
The <hegemonikon> has four powers: imagination, reason, impulse and assent. Firstly imagination is either sensory or mental reproductions of past phantasies. Secondly, reason is the faculty of making sense of things, applying logic. Thirdly, impulse is acting towards an imagination. In conclusion, assent is the action which comes after an evaluation of the object of desire.
According to Stoics, the soul has eight parts which are streams of <pneuma>. Hence, seven of these eight parts are the senses (sight, hearing, smell, taste, touch), the reproductive faculty, the speech faculty. Then there is the central commanding faculty <hegemonikon>. Also the parts of the soul as extensions of <pneuma> originate in the <hegemonikon>. In fact, some analogies explain the architectonics of the soul: the soul is like an octopus, a tree, a spring of water, and also a spider’s web. Indeed, the analogies of octopus, tree, and spring all underline the unity of the soul and the notion that the faculties are in the <hegemonikon>. Moreover Stoics, together with Aristoteles (Aristotle), think that the cognitive center is in the chest, not the head.
<Hegemonikon> is ‘internal rational ruler’. And the rationality is crucial in determining its role as governing part of the soul.