Sure, housing was overpriced for a few different reasons. There's quite a few causes of it, you probably know a lot of them. But - it was definitely overpriced (in a "bubble").
Now, we're having what's called a "correction" - a correction is where housing prices come back into line with where they'd in a more sensible environment. This is where stupid and reckless people get burned, and people who were sensible and saved their money now buy at the correct market prices.
Krugman is saying we should print money, which strips the value of people holding cash via inflation. This transfers money from people holding cash to people holding debt (because during inflation, hard assets like housing increase in price relative to debt - mortgages). That takes money primarily from middle class people who were sensible and cautious, and distributes that money to a mix of middle class people who weren't sensible and to upper class people (who typically have significant debt and hard assets).
Krugman's basically saying - "whoa, whoa, whoa, we can't let this correction happen - instead, we should take money from people who didn't play in this mess and give it to people who did" - that is horrific.
> And since economics is not a science who decides what is good economics?
Economics can have falsifiable hypotheses, so it can be science at times. But you're right, I should have called Krugman's ideas reckless policy instead of economics. It's more policy than economics, yes.