The other day, a BBC producer from London called me up and asked me if I would care to comment on the recent big sell-off in the Indian stock markets. I confessed that I am not fully qualified to do so but added that in all honesty that my guess would be as good as any one else’s. Still I declined. The best we can do is pull out Keynes’s “animal spirits,” which unfortunately is not amenable to rigorous scientific or economic analysis. The essential story of the stock market …