Both Nick Clegg and Vince Cable give the economic problems of Greece and the eurozone as the reason for Liberal Democrat support for public spending cuts now rather than when the recovery is assured.
In an article in the New Statesman David Blanchflower, the former member of the Monetary Policy Committee and the one who got things right, sates bluntly: "The deteriorating conditions in the eurozone have made it even more dangerous to cut (public) spending now."
The Conservative argument for cuts now is that they will boost confidence in the financial markets, floating on this bed of confidence industry will invest, and private spending will more than fill the gap left by the cuts in public spending. Given that the eurozone is our major export market, if it is in trouble then an export led stimulus becomes more difficult. In addition, to quote the Blanchflower article again: "If the pound... appreciates against the euro, the progress that the stimulus achieved in the UK would be thrown into reverse and growth would be even lower."
Blanchflower also points out that the US, which at roughly 12% has a similar level of current public borrowing as the UK, is not cutting public expenditure, nor are most of our major competitors
I suspect that the Liberal Democrat conversion to cuts now owes more to the malign effect of the chemistry than to the economic realities. We should stick to our Keynesian guns.