Last week, earnings surprises from the likes of Apple (AAPL), Caterpillar (CAT), and Starbucks (SBUX) helped push the Dow Jones Industrial Average past the psychologically-important 9000 level for the first time since early January. Now the question on our pundits' minds is: How long can this rally last?

With so much of the recent run predicated on less-bad-is-good news, no one is calling this a case of fundamentals driving share prices. After all, the economy isn't forecast to grow again until the third quarter and even then growth is expected to be anemic at best. Clearly other forces technical, psychological and perhaps even mystical are driving the rally, but the good news is that even the more pessimistic pundits see additional catalysts in second-quarter earnings reports.

"Friends, this is a faith-based rally, pure and simple," writes bearish David Rosenberg, chief economist and strategist at Gluskin Sheff. "And, as powerful as it is, this rally to new post-Lehman highs is being driven primarily by the technicals. Momentum is extremely strong at this time, and this often exerts a self-perpetuating move in the market, and in both directions."

Rosenberg says investors can do two simple, easy things to protect themselves from such extremes: Keep an extra careful eye on valuations and force yourself to lock in gains when the momentum reverses.

Liz Ann Sonders, chief investment strategist at Charles Schwab (SCHW), is more optimistic than Rosenberg, but she, too, underscores the role that momentum is playing in the rally. "The train has been leaving the station for many indexes, and investors don't want to be left on the cash platform," Sonders writes. She says investors are taking their cash and putting it into just about anything higher-risk bond sectors, emerging markets, U.S. stocks, commodities you name it.

"It's been my strong view that a lot of what we're seeing is 'capitulation in' vs. the 'capitulation out' that tends to occur as bear markets are ending," Sonders says. "I don't think we're finished with that process, but it won't last forever."

Ed Yardeni, president of Yardeni Research, sees the market remaining range-bound for another month or so, but acknowledges that second-quarter surprises could provide a lift. "Sideways could still be the direction for the stock market over the rest of the summer, before it heads decisively higher again, as I expect," Yardeni writes. "What would it take to move stock prices higher on a fundamental basis? More positive earnings would certainly do the trick," says Yardeni.

So far the rate of upside earnings surprises is "off the charts," writes Paul Hickey, founder of Bespoke Investment Group. True, we still have a long way to go through the current earnings season, but nearly 71% of companies reporting have beaten estimates. "Investors were worried heading into this earnings season that last quarter's numbers would be difficult to top, causing the market to struggle," he says. "However, the current earnings season has come in much stronger than last quarter so far."

If corporate earnings can continue that run, the market shouldn't have any problems holding onto its uptrend throughout earnings season, says Hickey.

Meanwhile, Jeffery Saut, chief investment strategist at Raymond James, does Hickey one better. He says one novel aspect of this recession is that productivity has actually increased because corporations have cut costs, setting us up for stronger, more sustainable gains (that is, predicated on something less ephemeral than technicals and momentum) later this year.

"The implication is that if demand picks up, the earnings rebound in the back-half of this year could be a lot stronger than most expect," Saut writes. "And that, ladies and gentleman, could be the carrot in front of the proverbial horse."