Whether you're an economic bad-news bear or a raging real-estate bull, one fact is indisputable: Mortgage-rate declines during the past 10 days have opened up opportunities for buyers and owners of homes that we haven't seen for nearly two years.

That's not to say mortgage money has suddenly gotten cheap or is headed back to the single digits. Forget those notions. Fourteen-percent-rate home loans aren't bargain basement by any standard, and the 9 percent fixed-rate mortgage is nowhere in sight.

But if you've been waiting for a break in the money market to start looking for a home--or to refinance that "creative" balloon note that's coming due--this could be it. It could also be a time to take a hard look at second mortgages, if you have a need to tap the equity frozen in your home.

Here's a perspective on why that's so, based on discussions with several top mortgage-market economists in the country.

No one--not even the Wall Street oracles whose words rock the stock market--knows how long or steep the current interest-rate declines will be. No one has a fail-safe system for forecasting interest rates six to 12 months from now.

But a handful of analysts have better-than-average records on forecasting, even if they don't agree about what's happening in the market today. Henry Kaufman of Salomon Brothers, for example, believes we've got a year's worth of slowly declining rates coming our way.

Tim Howard, the highly respected chief economist for the Federal National Mortgage Association, or Fannie Mae, believes the rate decreases we're seeing signal the long-term "crumbling" of the inflation-induced, superheated rate structure we've built up over the past decade.

Howard expects prime, conventional (non-government) mortgage quotes of 14 1/2 to 15 percent to be common within the next four to eight weeks and further, smaller declines to occur well into 1983.

"We're not in a classic interest-rate 'window' that's going to quickly close" with rates suddenly bounding up again, Howard predicts. Adjustable-rate loans may drop close to 12 percent in the next six months, he says, and "that should be low enough to enable a lot of people to buy and sell houses" who are currently squeezed out of the market.

If Howard and Kaufman are right, you've got time--perhaps three to six months--before mortgage rates bottom out. But you should know that Howard's and Kaufman's views are hardly unanimous.

Tom Parliment, economist for the U.S. League of Savings Associations in Chicago, argues that we are in a temporary period of lower rates that probably won't last much more than two months.

Once the Treasury begins moving back into the market to raise capital to feed the deficit, possibly right after the November elections, he says, "I don't see how rates will have anywhere to go but up." Parliment expects 14 percent rates during that window, but not much better. Afterwards, it's anybody's guess.

"I hate to be a bear when things look so good," he says, "but I am."

Another top economist, Tom Harter of the Mortgage Bankers Association of America, sees the market bottoming out around 15 percent in October, and forecasts a slow increase in rates into 1983. "I wouldn't bank on really big declines in mortgage rates," Harter counsels. "There's just too much demand out there for the available money, particularly if people begin rolling over their short-term, creative-financing balloon notes all at once." Harter also worries about the Treasury's borrowing after the election.

Some of the best minds in mortgage economics agree that rates have at least two months of moderation still to go. But they're not sure if those two months may be all we get this time around.

In deciding on a strategy for yourself, flip a coin and take your pick. But keep these points in mind:

If you've got to refinance short-term debt on your house within the next half year, give serious thought to a new, long-term, adjustable-rate mortgage (ARM). Rates on some yield-sensitive adjustable loans up to $107,000 are already down to 12.9 percent. If you believe analysts Howard and Kaufman are right, hook onto an ARM and take the ride down further.

Large, long-term second mortgages from local, Fannie Mae-approved lenders have dropped to just above 15 percent (plus service fees) for the first time. They can be a quick, cost-effective way to get tens of thousands of dollars of cash out of your house for investment, college costs or other big-ticket expenditures.

If you believe (along with the bad-news bears) that we're in a short-term rate "window," and you need long-term, fixed-rate money for housing, start talking to lenders now. The 14 percent some of them are offering today could be a mere memory by November.

Remember that the very lowest rates around don't come from professional lenders. They come from individual sellers of houses. They come from builders who will "buy down" your rate three to four points below conventional market rates. With the market heading for 14 percent, don't be shy. Bargain for 10 or 11 percent.