present-aim theory See PARFIT. pre-Socratics, the early Greek philosophers who were not influenced by Socrates. (Generally they lived before Socrates, but some are contemporary with him or even younger.) The classification (though not the term) goes back to Aristotle, who saw Socrates’ humanism and emphasis on ethical issues as a watershed in the history of philosophy. Aristotle rightly noted that philosophers prior to Socrates had stressed natural philosophy and cosmology rather than ethics. He credited them with discovering material principles and moving causes of natural events, but he criticized them for failing to stress structural elements of things (formal causes) and values or purposes (final causes). Unfortunately, no writing of any pre-Socratic survives in more than a fragmentary form, and evidence of their views is thus often indirect, based on reports or criticisms of later writers. In order to reconstruct pre-Socratic thought, scholars have sought to collect testimonies of ancient sources and to identify quotations from the pre- Socratics in those sources. As modern research has revealed flaws in the interpretations of ancient witnesses, it has become a principle of exegesis to base reconstructions of their views on the actual words of the pre-Socratics themselves wherever possible. Because of the fragmentary and derivative nature of our evidence, even basic principles of a philosopher’s system sometimes remain controversial; nevertheless, we can say that thanks to modern methods of historiography, there are many points we understand better than ancient witnesses who are our secondary sources. Our best ancient secondary source is Aristotle, who lived soon after the pre-Socratics and had access to most of their writings. He interprets his predecessors from the standpoint of his own theory; but any historian must interpret philosophers in light of some theoretical background. Since we have extensive writings of Aristotle, we understand his system and can filter out his own prejudices. His colleague Theophrastus was the first professional historian of philosophy. Adopting Aristotle’s general framework, he systematically discussed pre-Socratic theories. Unfortunately his work itself is lost, but many fragments and summaries of parts of it remain. Indeed, virtually all ancient witnesses writing after Theophrastus depend on him for their general understanding of the early philosophers, sometimes by way of digests of his work. When biography became an important genre in later antiquity, biographers collected facts, anecdotes, slanders, chronologies (often based on crude a priori assumptions), lists of book titles, and successions of school directors, which provide potentially valuable information.
By reconstructing ancient theories, we can trace the broad outlines of pre-Socratic development with some confidence. The first philosophers were the Milesians, philosophers of Miletus on the Ionian coast of Asia Minor, who in the sixth century B.C. broke away from mythological modes of explanation by accounting for all phenomena, even apparent prodigies of nature, by means of simple physical hypotheses. Aristotle saw the Milesians as material monists, positing a physical substrate – of water, or the apeiron, or air; but their material source was probably not a continuing substance that underlies all changes as Aristotle thought, but rather an original stuff that was transformed into different stuffs.
Pythagoras migrated from Ionia to southern Italy, founding a school of Pythagoreans who believed that souls transmigrated and that number was the basis of all reality. Because Pythagoras and his early followers did not publish anything, it is difficult to trace their development and influence in detail. Back in Ionia, Heraclitus criticized Milesian principles because he saw that if substances changed into one another, the process of transformation was more important than the substances that appeared in the cycle of changes. He thus chose the unstable substance fire as his material principle and stressed the unity of opposites. Parmenides and the Eleatic School criticized the notion of notbeing that theories of physical transformations seemed to presuppose. One cannot even conceive of or talk of not-being; hence any conception that presupposes not-being must be ruled out. But the basic notions of coming-to-be, differentiation, and indeed change in general presuppose not-being, and thus must be rejected. Eleatic analysis leads to the further conclusion, implicit in Parmenides, explicit in Melissus, that there is only one substance, what-is. Since this substance does not come into being or change in any way, nor does it have any internal differentiations, the world is just a single changeless, homogeneous individual. Parmenides’ argument seems to undermine the foundations of natural philosophy. After Parmenides philosophers who wished to continue natural philosophy felt compelled to grant that coming-to-be and internal differentiation of a given substance were impossible. But in order to accommodate natural processes, they posited a plurality of unchanging, homogeneous elements – the four elements of Empedocles, the elemental stuffs of Anaxagoras, the atoms of Democritus – that by arrangement and rearrangement could produce the cosmos and the things in it. There is no real coming-to-be and perishing in the world since the ultimate substances are everlasting; but some limited kind of change such as chemical combination or mixture or locomotion could account for changing phenomena in the world of experience. Thus the ‘pluralists’ incorporated Eleatic principles into their systems while rejecting the more radical implications of the Eleatic critique. Pre-Socratic philosophers developed more complex systems as a response to theoretical criticisms. They focused on cosmology and natural philosophy in general, championing reason and nature against mythological traditions. Yet the pre-Socratics have been criticized both for being too narrowly scientific in interest and for not being scientific (experimental) enough. While there is some justice in both criticisms, their interests showed breadth as well as narrowness, and they at least made significant conceptual progress in providing a framework for scientific and philosophical ideas. While they never developed sophisticated theories of ethics, logic, epistemology, or metaphysics, nor invented experimental methods of confirmation, they did introduce the concepts that ultimately became fundamental in modern theories of cosmic, biological, and cultural evolution, as well as in atomism, genetics, and social contract theory. Because the Socratic revolution turned philosophy in different directions, the pre-Socratic line died out. But the first philosophers supplied much inspiration for the sophisticated fourthcentury systems of Plato and Aristotle as well as the basic principles of the great Hellenistic schools, Epicureanism, Stoicism, and Skepticism. See also ELEATIC SCHOOL, IONIAN PHILOS- OPHY, MILESIANS , PARMENIDES , PYTHAGO — RA. D.W.G.