The scope of this chapter is dauntingly broad, since Avicenna was the central figure in the history of Arabic-Islamic philosophy. Before Avicenna, falsafa (Arabic Aristotelian and Neoplatonic philosophy) and kalām (Islamic doctrinal theology) were distinct strands of thought, even though a good deal of cross-fertilization took place between them. After Avicenna, by contrast, the two strands fused together and post-Avicennian kalām emerged as a truly Islamic philosophy, a synthesis of Avicenna’s metaphysics and Muslim doctrine.
To talk about the sources, evolution, and influence of Avicenna’s ideas is, in fact, to talk about over two thousand years of philosophical activity. Avicenna’s sources begin with Aristotle in the fourth century B.C.E. and include the late antique Greek Aristotle commentators, both Peripatetic and Neoplatonist. Avicenna himself was extremely prolific: between 40 and 275 titles have been attributed to him by bibliographers ranging from his student Jūzjānī to the late Egyptian scholar Georges Anawati, with approximately 130 reckoned to be authentic by the Iranian scholar Yahyā Mahdavī. What is more, his ideas evolved during the course of his career,with the result that, as with Plato’s and Aristotle’s thought, Avicenna’s philosophy will often resist our attempts to systematize it, and his position on a number of important philosophical issues will appear frustratingly underdetermined. As for Avicenna’s impact, it was felt acutely in both the Islamic world and in Christian Europe.