Posidonius Biography

Stoic philosopher, scientist, and historian. A Syrian Greek from Apamea on the Orontes (Syria), he was educated at Athens under Panaetius, but settled in Rhodes, a prosperous free city with already a reputation for philosophy and science. Granted citizenship, he took a significant part in public life as prytanis (‘president’, a magistrate's title), and as a member of at least one embassy to Rome in 87/6. Probably in the 90s he embarked on long tours of research to the west, visiting certainly Spain, southern Gaul, and of course Rome and Italy. Thereafter his School in Rhodes became the leading centre of Stoicism, and a general mecca not only for intellectuals, but for the great and powerful of the Roman world such as Pompey and Cicero.

The range of his writing is astonishing. In addition to the conventional departments of philosophy (Natural philosophy, ethics, logic), he wrote penetratingly on astronomy, meteorology, mathematics, geography, hydrology, seismology, zoology, botany, anthropology, and history. Some thirty titles survive over this field, but no complete work. This has led to a crux of methodology in Posidonian scholarship. Earlier this century research inspired by K. Reinhardt concentrated on a wide range of supposed echoes of Posidonian influence conjectured from horizontally parallel passages in later authors as the main tool for reconstructing his philosophy; but the uncertainty and dangerously subjective nature of this process, although at times illuminating, produced contradictory results. A fresh start has been made by the collection and study of the attested fragments which form a more secure base for what can be accepted as evidence, and offer a new picture.

Posidonius has been dubbed unorthodox in his Stoicism, but this is a misconception. He was not so regarded by his contemporaries, and he did not diverge from the fundamental tenets. He believed rather in the development of philosophy by continued interpretation in the light of subsequent criticism of the basic ideas of the founders and ‘the old authorities’. At that level there had always been divergence of interpretation in the Stoa, as between Ariston and Chrysippus. So Posidonius had strikingly original things to say within the context of Stoic natural philosophy in defence of the ultimate principles as material without quality or form; on problems of destruction, generation, continuity and change related to the individual; on the problem of ‘now’ in time viewed as a continuum; on a finite cosmos surrounded by infinite void; and in logic, on the criterion of truth, dialectic, and on the relational syllogism.

On the other hand he was convinced that in ethics Chrysippus had seriously distorted Stoicism with his monolithic rational psychology which defined emotion as mistaken judgement, and so failed to explain the cause and operation of emotions and hence the major questions in moral behaviour. Posidonius argued for a return to irrational faculties of mind with affinities towards pleasure and power. These were natural, but not good. Only our rational affinity for moral virtue he recognized as good and absolute. Hence the uncompromising Stoic end of virtue alone is preserved, despite some ancient and modern misunderstandings. Posidonius claimed that he could now explain the mechanics of moral choice, moral responsibility (since the root of evil lies within us), and moral education which required behavioural therapeutics as well as rational argument. His attack on Chrysippus in his book On Emotions as culled from Galen's De Placitis rests on three grounds: respect for the facts, consistency derived from deductive proof, and under standing sprung from explanation of the causes of phenomena. Posidonius was himself famed for all three in antiquity. They are the key for the coherence of his own work.

In the first place, he promoted logic from being the organon or tool of philosophy to that organic part of it which as bones and sinews supplied the articulation and dynamic of its structure. From the model of Euclidean mathematics, in whose foundations he was much interested, he regarded axiomatic deductive proof as the top-down causal explanation of the cosmic nexus. The tools of philosophy, and this is explicitly stated, now become the special sciences, a completely original concept peculiarly apposite for the material continuum of the Stoic universe. The sciences were thus necessary for natural philosophy, and the two complementary, but not equal. For while science supplied the descriptive factual pattern of phenomena as the cosmic map on which their rational organization may be traced, and so included the plotting of their immediate relationship of antecedent causation, and even offered possible alternative explanatory hypotheses at that level, only philosophy could provide final and complete explanation of causes or aetiology by its incontrovertible method of deductive proof from assured axiomatic premisses established by the natural philosophers. These procedures demanded precise distinction between different kinds of cause, but the details of the synthesis and interaction of natural philosophy and science are largely missing because of the lack of interest of reporters like Strabo. Some of Posidonius' own research in the sciences is remarkable, such as a lunar theory of the periodicity of tides which held sway until Newton; or his ingenious method of measuring the circumference of the earth leading to the establishment of latitudinal bands. On Ocean was an extraordinary work ranging from the astronomical establishment of geographical zones and so physical and climatic conditions, to human geography and anthropology. It is one of the lost books of antiquity one would most like to recover.

The same relationship holds for history and ethics, for history with its descriptive framework of actual social behaviour was his necessary tool for moral philosophy. The History was a major work in its own right of 52 books covering the period from 146 BC probably to the mid-80s and possibly unfinished. Its scope was all-embracing of the Mediterranean-centred world, from the histories of Asia Minor to Spain, Egypt and Africa to Gaul and the northern peoples, Rome and Greece. It was packed with formidable detail of facts and events, both major and minor, global and local, and of social and environmental phenomena. But the unifying factor of the huge canvas, factually drawn and sharply critical of credulous legend was, as Athenaeus implied and the tone and presentation of the brief Athenian tyranny of Athenion in 88 BC demonstrates, a moralist's view of historical explanation, where events are caused by mind and character in the relationship between ruler and ruled, and by tribal or racial character in social movement and motives. Hence his detailed interest in ethnology (Italian, Roman, Gallic, Germanic), i.e. ethology operating as cause. Again, such studies offer immediate historical explanation; final aetiology and principal causes come from the philosophical study of psychology and ethics.

His style, vivid, forceful and highly coloured, still gleams fitfully through the fragments. It so impressed such an authority as Cicero that he importuned Posidonius to write up his cherished consulate. The manner of declining showed a diplomat of enviable tact.

Posidonius' position in intellectual history is remarkable not for the scattered riches of a polymath and savant, but for an audacious aetiological attempt to survey and explain the complete field of the human intellect and the universe in which it finds itself as an organic part, through analysis of detail and the synthesis of the whole, in the conviction that all knowledge is interrelated.

A dominant figure in his lifetime, his subsequent reputation and influence have been overstressed to pandemic proportions and require re-examination; but the impact was considerable and continued at least to the 6th cent. AD. In mainstream Stoicism he did not supplant Chrysippus of Soli, and it was often outside the School, and not least in the sciences and history that he was consulted. The riches of the details tended to obliterate the grand design.

Ian Gray Kidd