Stanford Encyclopedia of Philosophy
1. Who Were the Presocratic Philosophers?
Our understanding of the Presocratics is complicated by the incomplete nature of our evidence. Most of them wrote at least one “book” (short pieces of prose writing, it seems, or, in some cases, poems of not great length), but no complete work survives. Instead, we are dependent on later philosophers, historians, and compilers of collections of ancient wisdom for disconnected quotations (fragments) and reports about their views (testimonia). In some cases, these sources had direct access to the works of the Presocratics, but in many others, the line is indirect and often depends on the work of Aristotle, Theophrastus, and other ancient philosophers who did have access. The sources for the fragments and testimonia made selective use of the material available to them, in accordance with their own special, and varied, interests in the early thinkers. (For analyses of the doxographic tradition, and the influence of Aristotle and Theophrastus on later sources, see Mansfeld 1999, Runia 2008, and Mansfeld and Runia 1997, 2009a, and 2009b.) Although any account of a Presocratic thinker has to be a reconstruction, we should not be overly pessimistic about the possibility of reaching a historically responsible understanding of these early Greek thinkers.
Calling this group “Presocratic philosophers” raises certain difficulties. The term was made current by Hermann Diels in the nineteenth century, and was meant to mark a contrast between Socrates who was interested in moral problems, and his predecessors, who were supposed to be primarily concerned with cosmological and physical speculation. “Presocratic,” if taken strictly as a chronological term, is not quite accurate, for the last of them were contemporaneous with Socrates and even Plato. Moreover, several of the early Greek thinkers explored questions about ethics and the best way to live a human life. The term