JACKSON HOLE, Wyo. (CNN/Money) - It's not MY fault the stock market bubble burst and it was never my job to make sure we didn't get one in the U.S. economy: That message came through loud and clear in Alan Greenspan's remarks here this morning.

Every year in Jackson Hole, Wyo., the chairman of the Federal Reserve kicks off the Kansas City Fed's two-day conference with a brief speech. The topic this year is "Rethinking Stabilization Policy," so the topic of how the Fed could and should use monetary policy to deal with the recent stock market bubble is certainly appropriate.

Greenspan basically said there was no way to know for sure if a stock bubble was forming in the late 1990s. With no way of knowing for sure, there was no way to justify the number and size of interest rate increases it would have taken to stop the bubble from inflating. And even if the Fed had been willing to implement Draconian measures, Greenspan seems to doubt they would have been effective. No if's, and's or but's.

Over the past three years, a number of stock market types -- money managers in particular -- complain that the Fed "blew" it -- either by not raising rates early (preventing the bubble) or by raising rates (causing the bubble to deflate).

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Upon hearing the speech today, I couldn't help but wonder: Is the criticism of Greenspan's handling of the stock market bubble so pervasive and serious that he feels he must go on the offensive with a strong defense like this one?

More than one economist here brought up the issue of Greenspan's legacy. As the day when he inevitably steps down draws nearer, the question of how he will go down in history is also coming to the fore. And although his record is jam packed with successes, including presiding over the longest economic expansion in U.S. history, he may now be worried that this final chapter of his chairmanship will be deemed a misstep, a policy failure.

Another policy wonk wondered about strategy: why here, why now? Greenspan is so "shrewd," he observed, he never says anything without a good reason. That musing led yet another economist to wonder if Greenspan is getting ready to step down soon and, knowing this, trying to make sure that history is written in a way that is favorable to him.

As for the actual substance of Greenspan's argument, economists here seem to agree that the whole question of what a central bank can and can't do to deal with bubbles the likes of which may only form once or twice in a century is open to debate. And many here seemed sympathetic to Greenspan's position.

However, that doesn't mean there wasn't some head-scratching and criticism.

Angry -- that's how one participant reacted. "After running the central bank for 15 years, with a great deal of success, you'd think he could admit to getting this wrong," he fumed after the speech. Said another, "He presented two extremes: the Fed doing nothing to stop the bubble or pushing rates up so much that the economy goes into recession -- as if there was nothing in the middle."

It would be easy to dismiss this as an academic issue that matters only to policy wonks, academics, and nerds like me who find all this fascinating. Problem is, as a longtime Fedwatcher commented to me today, if the Fed hasn't learned from this episode and insists that it played no part in the bubble that developed, then we all may suffer if a bubble forms again and policy-makers, instead of learning from the past, just fold their arms and say, "It's not my job, man."

Kathleen Hays co-anchors Money & Markets, airing Monday to Friday on CNNfn, and appears throughout the day reporting on the economy and how it affects financial markets. As part of CNN's Business News team, she is also a regular contributor to Lou Dobbs Moneyline.