The term Stoic categories refers to Stoic ideas regarding categories of being: the most fundamental classes of being for all things. The Stoics believed there were four categories (substance, quality, disposition, relative disposition) which were the ultimate divisions. Since we do not now possess even a single complete work by Zeno of Citium, Cleanthes or Chrysippus what we do know must be pieced together from a number of sources: doxographies and the works of other philosophers who discuss the Stoics for their own purposes.
The present information comes from Plotinus and Simplicius, with additional evidence from Plutarch of Chaeronea and Sextus Empiricus. According to both Plotinus and Simplicius there were four Stoic categories, to wit:
A simple example of the Stoic categories in use is provided by Jacques Brunschwig:
I am a certain lump of matter, and thereby a substance, an existent something (and thus far that is all); I am a man, and this individual man that I am, and thereby qualified by a common quality and a peculiar one; I am sitting or standing, disposed in a certain way; I am the father of my children, the fellow citizen of my fellow citizens, disposed in a certain way in relation to something else.
Stoicism, like Aristotelianism is derived from Platonic and Socratic traditions. The Stoics held that all being (ὄντα) — though not all things (τινά) — are corporeal. They accepted the distinction between concrete bodies and abstract ones, but rejected Aristotle's teaching that purely incorporeal being exists. Thus, they accepted Anaxagoras' idea (as did Aristotle) that if an object is hot, it is because some part of a universal heat body had entered the object. But, unlike Aristotle, they extended the idea to cover all accidents. Thus if an object is red, it would be because some part of a universal red body had entered the object.
In addition, the Stoics differed from Aristotle in their sharp distinction between concrete and abstract terms. Technically speaking all four Stoic categories are of concrete bodies. For Aristotle white, whiteness, heat, and hot were qualities. For the Stoics, however, quality refers to white, but not whiteness; hot, but not heat. Furthermore, they believed that there are concrete bodies with no corresponding abstraction, something that makes no sense in Aristotelian terms.
It was apparent that the mere distinction between concrete substance and concrete quality was not a sufficient basis for logic. Socrates in the Hippias Major had pointed out problems in Anaxagoras' approach, explaining all attributes through their presence in a body in the way one body may be contained in another. In that dialog, Hippias tried to explain beauty to Socrates. Socrates finds fault with his explanations, that beauty is a beautiful maiden, that beauty is gold, that beauty is health, wealth and a long life.
Aristotle solved the problem in proposing that accidental attributes are non-substantial beings that inhere in substances. He defines this presence saying "By being 'present in a subject' I do not mean present as parts are present in a whole, but being incapable of existence apart from the said subject." (The Categories 1a 24–26)
Such incorporeal presence caused problems to the Stoics in saying that the οὐσία of a thing is its matter. It is easy to understand the problem. If there is an insubstantial being, in Athens somehow present in Socrates, causing him to be substantially present in Athens we seem to be faced with an infinite regression, for there would seem to be an insubstantial Socrates in the insubstantial Athens in Socrates, in Athens, etc. Ultimately, who is to say who is the real Socrates and what is the real Athens? Similar arguments can be made of Aristotle's other categories. Was there an insubstantial running in Archimedes causing him to run naked through the streets of Syracuse, shouting out his immortal "Eureka"? Was there an insubstantial fist in Athena causing her to strike Aphrodite as the Iliad recounts?
Once Hera spoke, Athena dashed off in pursuit,
delighted in her heart. Charging Aphrodite,
she struck her in the chest with her powerful fist.
It was the effort to solve the problems raised by the Platonists and Peripatetics that led the Stoics to develop their categories, somehow disposed and somehow disposed in relation to something. The fact that Stoicism, rather than either Platonism or Aristotelianism became the prominent philosophy of the ancient world is due in part to the approach they took to the problem.
According to Stephen Menn the first two categories, substance and quality, were recognized by Zeno. The fourth category somehow disposed in relation to something seems to have been developed by the time of Aristo. The third category, somehow disposed is first seen in Chrysippus.
The need for relative terms, seen in the fourth category somehow disposed in relation to something is more obvious than the need for the third category somehow disposed and so it seems to have arisen first.
Aristotle had used relative terms in a somewhat general way. "Those things are called relative, which, being either said to be of something else or related to something else, are explained by reference to that other thing." (The Categories 6a 37–38) Thus he says that knowledge and the thing known are relatives. One can certainly consider knowledge as something properly existing in its subject. Aristotle himself recognized a much different kind of relationship. "In respect of relation there is no proper change; for, without changing, a thing will be now greater and now less or equal, if that with which it is compared has changed in quantity." (Metaphysics 1088a 33–35) In the first case, a relative term can be said to be something in its subject. In the second case, it can not. Thus, the need for somehow disposed in relation to something to explain how one thing can be relative to another without the presence of anything corporeal in a subject.
According to Stephen Menn, the third category, somehow disposed probably was recognized first in relation to the virtues. According to Socrates, virtue was a sort of knowledge. The wise man will act virtuously, since he will see it as the right thing to do. But the ignorant man can not avoid vice. The Stoic position held that a sage will possess all the virtues in their fullness. Aristo had argued that there is really only one virtue differentiated as somehow disposed in relation to something. This seemed to be too much like the Megarian position. Chrysippus thus came to see the virtues as distinct bodies, inseparable from each other somehow disposed in themselves and not in relation to something. Thus the need for the third category.
Plotinus criticized both Aristotle's Categories and those of the Stoics. His student Porphyry however defended Aristotle's scheme. He justified this by arguing that they be interpreted strictly as expressions, rather than as metaphysical realities. The approach can be justified, at least in part, by Aristotle's own words in The Categories. Boethius' acceptance of Porphyry's interpretation led to their being accepted by Scholastic philosophy.
The Stoic scheme did not fare as well. Plotinus wrote...
Besides, if they make life and soul no more than this "pneuma," what is the import of that repeated qualification of theirs "in a certain state," their refuge when they are compelled to recognize some acting principle apart from body? If not every pneuma is a soul, but thousands of them soulless, and only the pneuma in this "certain state" is soul, what follows? Either this "certain state," this shaping or configuration of things, is a real being or it is nothing.
If it is nothing, only the pneuma exists, the "certain state" being no more than a word; this leads imperatively to the assertion that Matter alone exists, Soul and God mere words, the lowest alone is.
If on the contrary this "configuration" is really existent- something distinct from the underlie or Matter, something residing in Matter but itself immaterial as not constructed out of Matter, then it must be a Reason-Principle, incorporeal, a separate Nature.