Because there's no objective, empirically based criteria for a tipping point; all such things are hypotheses which are falsified by the passage of time. I can t

Because there's no objective, empirically based criteria for a tipping point; all such things are hypotheses which are falsified by the passage of time. I can think of a few in the past 40 years. That's not to say there aren't 'tipping points' (you certainly can't prove they don't exist.)