The Economist is playing host to an online debate on whether innovations in finance over the past few decades have contributed to growth. Arguing the “pro” case is Ross Levine, an economist at Brown. On the “con” side, arguing that ever-more-complex financial instruments have enriched speculators while destabilizing markets, is Joseph Stiglitz, the Columbia economist and Nobelist. Online readers side 55 percent to 45 percent with Stiglitz.