W. Brian Arthur is an External Professor at the Santa Fe Institute and a Visiting Researcher at PARC (Palo Alto Research Center). Formerly he was Morrison Professor of Economics and Population Studies at Stanford University. One of the pioneers of complexity theory, he also formulated the influential “theory of increasing returns,” which offered a paradigm-changing explanation of why some high-tech companies achieve breakaway success. Former director of PARC John Seeley Brown has said of him, “Hundreds of millions of dollars slosh around Silicon Valley every day based on Arthur’s ideas.” Arthur is the recipient of the International Schumpeter Prize in Economics, and the inaugural Lagrange Prize in Complexity Science. He lives in Palo Alto, California.