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The Greek word aitia (or aition ) derives from the adjective aitios, meaning "responsible," and functions as such as early as the Homeric poems. It was originally applied to agents, and only later does it come to qualify nonsentient itemsalthough owing to the fragmentary nature of earlier sources, it is by no means clear when this transition takes place. But certainly by the latter part of the fifth century BCE, Hippocratic doctors were using the term, as were the historians Herodotus and Thucydides. It is in the latter, as well as in some of the Hippocratic texts, that the beginnings of the distinction of causal terminology can be found. Similar fine distinctions are also beginning to appear in the forensic and rhetorical traditions. In his discussion of the plague at Athens (Peloponnesian War 2.4754), Thucydides disavows any knowledge of its origins or "what causes (aitiai ) may be adduced adequate to explain its powerful natural effects" (2.48), and notes that "in some cases there seemed to be no prophasis " (2.49). A prophasis is an external cause, or occasion, or antecedent event correlated with an outcome. This word, as well, has Homeric roots, but it also has a legal (and more general) sense of pretext. Hippocratic texts also contrast prophaseis with aitiai, and in the same general way: Prophaseis are the observable antecedent signs, aitiai the inferred inner, structural facts causally responsible for the outcome. Aitiai are now closely linked with the notion of phusis or nature, the primary matter of pre-Socratic inquiry. If things have naturesinternal structuresthen those natures will explain how and why things behave the way they do.

Plato was the first philosopher to subject the concept of an aitia to detailed examination. Whereas generally an aition is "that because of which something comes to be" (Cratylus 413a), and "the cause and the productive may rightly be said to be identical" (Philebus 26e), Plato treats these characterizations generallythey do not restrict causation to efficient causation. Indeed, at Phaedo 95e103b, he takes the pre-Socratics to task for concentrating on mechanical causation at the expense of teleology: It is only if you know why things are for the best that you understand them. Moreover, Plato elaborates a thesis of necessity and sufficiency with regard to cause and effect (or explanans and explanandum ): If F 's cause G 's, then there is no F without a G, and vice versa.

Aristotle followed Plato in espousing teleological explanations, and referring to them in the language of aitiai. Final causes are one of his four causal (or explanatory) types, along with material, efficient, and formal (Physics 2.3). But unlike Plato, Aristotle's final causes in nature presuppose no agency. Where Plato spoke of the Craftsman who designed everything for the best (Timaeus ), Aristotle makes finality an irreducible component of nature itself. Nature is goal-directed, and no adequate account of natural processes can ignore that fact (as those of the atomists and other mechanists do). As Plato had before him, Aristotle thinks explanatory resources available to pure mechanism are inadequate to give a satisfying explanation of the order and regularity of the cosmos. The four causes are designed primarily to account for substances, and only derivatively for events and processes. Thus one might ask what makes an oak tree what it is. Firstly, its efficient causenamely its parent tree, which supplies the formal model from which it derives. Secondly, its material cause: There could be no oak tree without a suitable supply of matter for the form to mold. Thirdly, there is the form itself, deriving from the efficient causeyet from the moment the seed is created (or at least begins to germinate) it is an independent structural principle. And finally there is the endor completely expressed formtoward which the process of maturation is directed and in which it will culminate if all other (material) factors equal.

Aristotle seeks to apply this model, with varying success, to all cases of coming to be (although he allows that coincidences lack final causes: Physics 2.46); and that all of the factors involved may equally be called aitiai. Moreover, he believes that even abstract objects have formal causes (the formal cause of the octave is the ratio 2:1). Plato's Stoic successors, however, reserved the term aition for a physical productive causea body that brought about in another body an incorporeal effect, a predicate's coming to be true of it. They allowed matter a role in overall explanation, yet being passive by definition it could not be a cause; neither could it be disembodied goals or ends. These Stoic successors, or their contemporaries in the medical schools, turned to making further fine distinctions within the notion even more restricted, distinguishing between "perfect" or "sustaining" causes on the one hand and "antecedent" causes on the other. "Perfect" or "sustaining" causes were sufficient, necessary, and coterminous with their effectsand functionally correlated with themin that any increase or decrease in intensity in the one is matched by a similar change in the other, "antecedent" causes answered roughly to the earlier prophaseis : prior events that set a causal process in train but are not sufficient for it (since they require suitably constituted bodies upon which to act).

Skeptics were to argue that causes could not both precede and be coterminous with their effects; and that because cause and effect are relative terms, they cannot be conceived independently, as they must be if one is to explain the other. This and other such attacks in turn prompted doctors and philosophers such as Galen to even further conceptual refinements that continued at least until the third century CE, whereas Neoplatonists like Proclus would later insist that, properly speaking, all causes were immaterial (being the action of soul).

See also Aristotle; Causation; Plato; Stoicism.


Barnes, J., ed. The Complete Works of Aristotle. 2 vols. Princeton, NJ: Princeton UIniversity Press, 1984.

Cooper, J. M., ed. Plato: Complete Works. Indianapolis: Hackett, 1997.

Hankinson, R. J. Cause and Explanation in the Ancient Greek World. Oxford: Oxford University Press, 1998.

Warner, R. Thucydides: History of the Peloponnesian War. Harmondsworth, U.K.: Penguin Books, 1953.

R. J. Hankinson (2005)

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