There is no doubt that Democritus' atomism was widely appreciated and admired among thinkers of the fourth century BC. It was, of course, flagrantly at odds with any kind of Platonism, and so far as we can tell most philosophers tended to orientate themselves very clearly towards one or other of these apparently exclusive alternatives. What is distinctive about Aristotle is that, no doubt by a combination of reasons of temperament and circumstance, he attempted a kind of synthesis of, or compromise between, the two positions. In this respect, he can perhaps be compared with the more recent and thus familiar case of Kant, who similarly saw himself as achieving a historic reconciliation between the insights of empiricism and rationalism.
The tension between Platonic idealism and Democritean materialism set the stage for the development of Aristotle's thought, but we cannot hope now to reconstruct with confidence the precise plot of the drama.
It seems likely that Aristotle's ideas were forming during the first thirty, perhaps even forty, years of his life and that he inclined at various times now towards the materialist, now towards the idealist perspective, before reaching his final remarkable synthesis (or syntheses, as we shall see). It is unlikely that we will ever know for certain more than this, but my own feeling is that Aristotle's development up to the time at which he left the Academy after the death of Plato in 347 BC went approximately as follows.
His early years were dominated by the intellectual climate of the Northern Aegean in general and by his father's profession in particular.
As we have already seen, the Aegean basin, and perhaps especially its northern littoral, had always tended to produce thinkers of a relatively hard-headed and materialistic outlook. It tended to be in the West that philosophers dreamed of an ideal order transcending the mundanities of our imperfect world and in the East that the spirit of mechanistic explanation even of animate phenomena was most pervasive. This involved to a particular extent the profession of Aristotle's father, Nicomachus, which was that of medicine.
The history of Greek medicine is that of an institution of caste-like and exclusive character, which nevertheless was prepared to tolerate radical innovation and a critical attitude to accepted practices that would have been praised by Sir Karl Popper. The medical profession in Ancient Greece was a profession that one joined not by a formal qualification but by birth. All doctors claimed to be descendants of the legendary, or mythical, Asclepius, and membership of this descent-group was, it seems, not only a necessary but also, in the normal way, a sufficient cause for membership of the profession. Thus Aristotle would from his earliest awareness have known what his destined profession was to be.
He would no doubt soon have sensed the prestige attached to itinerant Asclepiad doctors and the cult of secrecy that tended to surround their art. But he would also, we may assume, have known of the bold and speculative writings that had been produced by the membership of the medical guild, writings which have come traditionally to be attached to the name of Hippocrates of Ceos. He may well have been brought up to think that speculation on the inner workings of natural processes, far from being an affront to religious susceptibilities, was actually a pious recognition of the wishes of Asclepius for his successors and heirs.
In assessing the influence on Aristotle of Nicomachus and the medical profession, we must take into account that his father died when Aristotle was merely ten years old. Whereas this probably weakened his direct connection with practising doctors and perhaps his own predetermination for a medical career, it may well have given a special place in his feelings to the naturalistic perspective that was at the heart of Greek medicine. His education between the ages of ten and seventeen was of the conventional Hellenizing kind favoured by the states that stood within the penumbra of the Greek world proper. This would no doubt have given him a reverence of a different kind for Athens and everything associated with it, which would have had some influence on his state of mind when he was dispatched by his father's former employer, the King of Macedon, to study in Plato's Academy.
Entering the Academy in the late 360s, he would have encountered idealist metaphysics in full cry and it is certainly possible that he fell immediately under its spell. It has often been pointed out that in the period of his stay in the Academy he wrote several works for popular consumption of an overtly Platonizing nature. It is unlikely that these were merely exercises or routine pieces of institutional propaganda. He seems to have lavished on them his rhetorical gifts, which had no doubt been sharpened by his tutors in Macedon, and the fragments that have survived suggest a powerful emotional identification with the aspirations of the Theory of Forms, as well as mastery of the arguments on which the Theory was held to rest. He did not - and this is crucial to the greatness of his own system - merely dismiss the perspective of idealism with the animus that scientifically minded philosophers have often felt against it.
Nevertheless, it seems likely that, perhaps by the 340s, when he had been in the Academy for some ten years, he was coming to see that a reconciliation of some kind had to be effected between the science of nature, especially as it related to living things, for which it is clear that he felt an extraordinary attraction, and the more abstract reflections that seemed to point away from the reality of the world of the senses towards a quite different ultimate structure of the world. It is the fact that he achieved this reconciliation with such mastery, and in a way so palatable to common sense and to perennial philosophical intuitions, that has made his system, for all its obscurities and even occasional absurdities, the intellectual foundation for the received metaphysics of the Western world.
It is best, I think, to see Aristotle's philosophy as being dominated by the following three questions. What is being and what are the things that are? How can the things that are undergo the changes that we see all around us in nature? How can the world be understood? It is, of course, true that his thinking covers a vast range of other major topics in the formal, empirical and philosophical domains, but he would have regarded these other topics as being dependent on, and in some way secondary to, the ones that I have given, in a way that was not reciprocal.
It is, in any case, these three questions that dominate his metaphysical theory. But if we wish to understand how he answers these questions in his mature metaphysics, contained in the central books of the Meta-physics, we must first look briefly at two other major works, the Categories and the Physics, which constitute preliminary stages of his metaphysical view, whether earlier stages in its evolution or preparatory contributions to its presentation.
