I'm saying that we don't know that Krugman was right or wrong in his assertion that that we should have authorized significantly more stimulus spending...and history certainly doesn't show he was right in this regard as you incorrectly asserted. Krugman was right about many things...but we have no way of knowing whether or not he was right on this particular point.
The evidence clearly indicates he was right. Under your standard of evidence we can never say anyone is right if they advocate different policy than the one that was followed. That is pretty obviously ridiculous.
