Markets and perceptions of the economic outlook change rapidly. Even two months ago most observers doubted predictions of a US recession, saw no need for a fiscal stimulus, and thought that inflation fears should constrain monetary policy. Now, Washington is more or less settled on a stimulus package that will exceed $150bn; markets at one point last week expected a Fed funds rate below 2 per cent by September. The debate about recession is now about how deep and global its impact will be.

There is enormous uncertainty around economic or financial forecasts. It is possible that pessimism will recede as declining interest rates and dollar exchange rates increase demand. It is more likely, though, that the situation will deteriorate further as perceptions of declining growth increase credit spreads and risk premiums in financial markets, leading to reduced lending, borrowing and spending exacerbating the pessimism about growth.