Cohesion

Cohesion, in Stoic physics, refers to the principle of cohesion that holds a body together and allows it to exist as a unity. It is not a merely mechanical bond, but an active internal tension that gives a body its consistency, continuity, and resistance to dispersion.

For the Stoics, everything that exists is corporeal. A body does not persist through a simple juxtaposition of parts, but because an internal force keeps those parts unified. The synektikón is precisely this force: that which prevents a body from dissolving, that which maintains its integrity and form.

This cohesion is ensured by pneuma, a principle that is both material and rational, which permeates bodies and structures them from within. Depending on its degree of tension (tonos), pneuma produces different levels of organization: mere cohesion in inanimate bodies, growth in living beings, sensation in animals, and reason in human beings. The synektikón corresponds to the most basic level of this structuring. It is essential to note that Stoic cohesion is not fixity. It is dynamic: a maintained balance of forces, a sustained tension rather than immobility. A body exists as long as this internal tension persists; when it relaxes, the body comes apart. Cohesion is therefore compatible with change, movement, and transformation.

Conceptually, the synektikón allows the Stoics to account for unity without appealing to transcendent forms or immaterial essences. An entity’s unity does not come from an external principle, but from what acts within it and runs through it. In this sense, cohesion is a paradigmatic expression of Stoic immanence.

Thus, the synektikón is not merely a physical concept, but an ontological key: to exist is to be held together from within. Cohesion is not what endures unchanged, but what continuously operates to sustain a being in existence.