Quote from Martinghoul:
So, like I promised, here's how I view this...
To me, your statement above is actually very telling. IMHO, the job of a Fed chairman (as well as a trader and/or risk manager, for that matter) is precisely about "making a guess based on a hypothesis supported by a theory", since, obviously, the future is completely unknown. In fact, even the present is largely obscured by a sort of "fog of war".
So suppose as a Fed chairman you're facing a bunch of outcomes, including the low probability (2 - 5%) outcome that you define as "utter ruin" (Great Depression, Japanification, secession, whatever). In fact, the consequences of the ruinous outcome are so dire that, even with a low probability, it makes the "expected value" of your future unacceptably negative. Also imagine that the set of available tools is limited and you don't have the ability, at short notice, to negotiate for a broader remit. What do you do? IMO, you do what you can, even if there are significant costs involved. In my mind, this is a situation similar to what a risk manager (or a good trader) faces if they find that they're in a trade that can totally destroy them. A good risk manager in this situation hedges, even if the hedge isn't perfect and/or costs too much. In my opinion, the logic above is legitimate justification for the initial rounds of QE. My disagreement with the need for QE3 stems from my subjective view that the probability of the "ruinous" outcome by the end of 2012 was very close to 0. To be fair, my view was supported by the pricing of various instruments in the mkt.
I realize that there are many parts of the above that are, to some extent, subjective. You may disagree with this or that specific element of the argument. However, to me, the logic is the important bit and, I believe, it is sound. Moreover, there's some historical precedent to support it.
And to add my final point, which, again, takes us full circle. That is why I have said all the things earlier about Rick Santelli. Based on what I have heard him say, he just doesn't think like a risk taker and/or trader. He sees his central scenario realized in the future with complete certainty. For a trader, that is the surest way to utter failure.