To be fair, Mr Greenspan did not argue that there were no bubbles, only that it was impossible to spot them while they were inflating.

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Both said that monetary and fiscal authorities should outline how they will step back from the rev-it-up policies since the global banking crisis, in order to achieve sustained, noninflationary growth (i.e. no bubbles).

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Inflation is quiescent with no asset bubbles reforming.

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No other major bubbles have burst back to where home prices are affordable again, and major cities from Shanghai to London to Vancouver to Melbourne and Sydney, Australia, are still going up or very near their peaks.

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"By that I mean try to imagine creating a cavity inside your mouth without any air bubbles and by letting in no air through your lips or throat -- it's basically impossible at sea level because the air pressure outside your mouth pushes the air pocket closed, " he said.

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Fisher would say there is no housing bubble when people are talking about housing bubbles.

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To be fair, no one can accurately predict the future, and only a rare few see bubbles for what they are before it is too late.

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Greed and recklessness always run rampant during bubbles, and the mania that engulfed housing and much of the financial sector was no exception.

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