One reason for this, he says, is that lower oil prices and the fall in the euro should help prevent the euro area falling back into recession. This could support share prices if only by reducing the risk of a big drop in earnings. Others believe continued growth in the US will support share prices. Patrick Legland at Societe Generale says that rising corporate earnings "could provide some relief for shares". Axa's Chris Iggo adds that a combination of falling oil prices and rising employment could generate a big rise in consumer spending.
On top of all this, negative real yields on government bonds make it likely that holders of safe assets will suffer a loss. The desire to avoid this could cause investors to switch into equities at the sight of any comforting economic news.
Nevertheless, some dangers remain. One is that central bankers might not be able to support share prices. Alastair Winter at Daniel Stewart & Co says it would be dangerous for investors to rely on the "Yellen put" - the Fed's tendency to loosen monetary policy to stop shares falling very far. And although many economists still expect the European Central Bank to adopt full-blown quantitative easing, they warn it could disappoint equity investors by being slow to do so.
Another danger, warns Erik Britton at Fathom Consulting, is that the euro area's "slide towards outright deflation" could trigger a renewed debt crisis; this is because falling prices would mean falling tax revenues and hence doubts about whether governments could service their future debts. Mr Britton warns that the sell-off in Greek government bonds could spread to Italy.
Perhaps the biggest reason for optimism, however, is simply that we are approaching the right time of year for shares. Research by Ben Jacobsen at the University of Edinburgh and Cherry Zhang of Nottingham University Business School has shown that stock markets around the world do much better between November and April than between May and October. This could be another year where the 'Halloween effect' proves itself.
