Elementary Questions About Keynesianism

I think I asked this question back in '09 or early '10, but I didn't get a satisfactory answer so I'll ask it again. I am certain that there is a simple answer to it, but I haven't yet seen it. I know some Keynesian economists occasionally read this blog, so I'm hoping they'll set me straight.

As far as I can tell, the whole Keynesian framework depends on the existence of a liquidity trap. Without it, as Krugman keeps repeating, normal rules of macroeconomics apply: trade is good, monetary policy is effective, etc. But in Depression Economics all that is turned upside down. The rules of the game change because of the constraint imposed by the liquidity trap. Normal macroeconomics doesn't work.

In the Keynesian framework monetary policy is ineffective at the zero lower bound because people (banks, businesses, households) hoard cash. Thus there is a decrease in aggregate demand, economic activity slows, unemployment increases, etc. I get all of that. Here's the leap that I can't make: why isn't that true of fiscal policy as well? If I use monetary policy to give people money and they hoard it, why would they not hoard money if I use fiscal policy to give them cash?* The whole idea of Depression Economics depends on a psychological model of mass peoples -- what Keynes called "Animal Spirits"** --  that would seemingly apply universally to all public policy intended to stimulate demand. I see no reason why businesses or households would respond to cheap/free money from the monetary authorities by not hiring, but respond to cheap/free money from the fiscal authorities by hiring.

In other words, if the monetary multiplier is small because of the hoarding impulse derived from animal spirits, then the fiscal multipler should be no greater and probably smaller, for a few reasons. Cash transfers on the fiscal side only moves the money once, and then it should be hoarded in the same way as cash from monetary policy (which is also moved once). But fiscal policy also incurs new debt, which must be serviced. That imposes real future costs in the form of interest -- which is admittedly quite small or even negative in the present environment -- and fiscal drag from future taxation, both of which can be anticipated. Tack on some waste/corruption/deadweight loss and it's hard to see how fiscal policy would be more effective than monetary policy at the zero lower bound or anywhere else. Even at a high discount rate monetary policy can always be cheaper than fiscal policy, so it should seemingly have a higher multiplier.

I freely admit my ignorance and stupidity in this matter. I understand that economics often makes no sense until someone explains it to you, and my economics education effectively ended with my undergrad major. So I'm asking someone to explain it to me: why do animal spirits negate monetary policy at the zero lower bound but not fiscal policy? I'm guessing it has something to do with financial intermediaries, but then doesn't that require an additional, separate assumption about psychology?

*The closing scene in the HBO adaptation of Sorkin's Too Big to Fail has Poulson muttering to one of his deputies something like "We gave the banks the cash; now they better spend it and get the economy moving". I'm sure that's apocryphal, but the whole point is that they didn't. They hoarded it, as a Keynesian would expect from monetary policy, but not from fiscal policy. Poulson, of course, was most concerned with the fiscal intervention.

**While I'm here, there's something else I don't understand: Why is it that Keynesians smirk at assertions that businesses aren't hiring between of "uncertainty" when their entire underlying model depends on precisely that claim? Partisans on the right surely miss part of the story when they attribute this uncertainty only to Obama's policies -- I agree with Summers when he said that the biggest uncertainty is over the entries on the order books, i.e. aggregate demand --  but the uncertainty that matters is over expected profits. One part of that equation is revenue, the other part is costs including regulatory and tax costs. Decreasing uncertainty over the former (in a positive direction) increases confidence and thus investment, but so does decreasing uncertainty over the latter (in a positive direction). Both sides seem to be right and wrong. Or, rather, incomplete without the other.