The inevitable bubble chatter will pick up steam again. The best reason to believe we're not in a bubble is that people are still talking about a bubble. It'l

The inevitable bubble chatter will pick up steam again. The best reason to believe we're not in a bubble is that people are still talking about a bubble. It'll take a few more years till we're really at a new peak of irrational exuberance, till everyone has forgotten the last bubble and the damage it caused, till huge valuations with no profits seem completely rational, and no one dares speak out for fear of looking a fool and missing out on the huge gains everyone else is making. At that point, when no-one is talking about bubbles any more (either pro or con), we've entered a new normal, and once again people are talking about the end of history, we'll be in a bubble. What could pop this bubble when it comes to fruition? There are lots of possibilities, but a dip in profits at one of the big advertising companies might be enough to stop acquisitions and hiring and hit valuation badly. No acquisitions means no exits, no exits means no investment, no investment means no advertising. When contractions arrive, they're often unexpected and impossible to stop, because markets run on confidence. Volatility over the last few decades is certainly very high, possibly caused by the huge dislocations of globalisation, robotics and computerisation - very similar to the industrial revolution. I see no reason why that volatility would end right now, we are still in a transition period between a collection of protectionist nation states and a global economy, and between an industrial and an information economy. That means more bubbles and more crashes.