I think we have by far the better of the argument. There is no tipping point.The chart says different:
Each and every blue bar tipping point is associated with rapid rise in debt. The condition becomes more drastic as accumulated debt levels rise. Notice that keeping the deficits down is associated with milder tipping points. Brad has a problem, there is no visible mainstream theory that proves more debt avoids the tipping point.
Brad puts up a scatter chart of multiple economies and does not see a particular tipping point, His chart will not tip, it is an average of average growth in a collection of nations. Krugman tried foisting that chart on us, it is a bogus piece of evidence and clearly the chart above speaks of danger signals.