After the wholesale discrediting of the strong form of the efficient markets hypothesis, Robert Shiller may be the most respected financial economist in the world at the moment. This is what he has to say on the last page of Justin Fox’s The Myth of the Rational Market:
Finance is a huge net positive for the economy. The countries that have better-developed financial markets really do better. . . . I think that we’re less than halfway through the development of financial markets. Maybe there’s no end to it.
I think Shiller’s first and second sentences are almost certainly true. There is a strong correlation between having a high material standard of living and having a relatively sophisticated financial system; think of the United States, Japan, and Germany as opposed to Zimbabwe, for example. But you can’t infer that more financial market “development” is always better. (I’m not saying that Shiller necessarily believes that, but most of the defenders of financial innovation take it for granted.)
Just because something is good, it doesn’t necessarily follow that more of it is better. Take food, for example. It’s pretty obvious that over a wide range – say from 0 to 1500 calories per day – more food is better for you. For most people that range probably extends up to 2000 calories or a little more. After that, not so much.