NEW YORK (CNNMoney.com) - All you guys sound like a broken record telling people they'll get bigger returns by investing in stocks. That hasn't been true the past five years, so why are you so convinced it will be true the next five? Retirees will starve if the next five years are like the last five.

-- Dennis Abshire, Carmel, Indiana

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Broken record? Why whatever do you mean, do you mean, do you mean...

Seriously. I can't (and wouldn't want to) speak for other personal finance columnists. But I can tell you that I've never made a practice of predicting stock returns, and certainly wouldn't try to do so over a period as short as five years.

But what I have said -- and continue to believe wholeheartedly -- is that anyone investing for the long-term ought to own stocks. Certainly not all of your money should be in stocks.

I've always recommended that investors should own both stocks and bonds, with the mix tilting more toward bonds and cash the shorter your investment horizon. (For more specific guidelines on how to divvy up your portfolio between stocks and bonds, check out our Asset Allocation tool.)

As for retirees, I think it's important that they invest in stocks too. Yes, retired investors should definitely own bonds as well, since fixed-income investments provide income and stability and, thus, more short-term safety. But equities help maintain purchasing power in the face of inflation during a retirement that these days can easily last 30 years.

Stocks' generally higher long-term returns can also give you a larger financial cushion throughout retirement. (For more on this cushion effect, click here. And to get more specific advice on how retirees should divvy up their portfolios between stocks and bonds, click here).

And you know what? That advice has served people pretty damn well. The reason is that stocks have without a doubt provided the highest returns over long periods of time, by which I mean 10 years or more. In fact, even if you look at five-year periods, stocks come out winners more often than bonds. For the 76 rolling five-year periods from 1926-1930 through 2001-2005, for example, stocks had the higher return 57 times, or 75 percent of the time.

Clearly, stocks do get clobbered at times. And if we knew in advance when those times would be, we could jump out of stocks just at the right time -- and get back in when the gains are ready to start rolling again.

But that's not realistic. Which is why prudent investors diversify. They hold a variety of different stocks -- large and small, growth and value -- and hedge with bonds.

Diversifying doesn't make you immune to stock setbacks, of course. But it can temper the severity of those downturns. And, just as important, having stocks as a core holding will allow you to participate in the big gains when stocks are on a run.

Which has been the case lately, by the way. Although stocks have performed poorly with annualized returns of just under 5 percent if you start counting from five years ago, they've gained about 11 percent over the past year (vs. 2.7 percent for bonds) and are up almost an annualized 20 percent over the past three years (vs. 2.9 percent for bonds).

I mention that not because I'm not predicting they'll continue that run. But I think it's important to know that one's assessment of how well or badly stocks are doing depends a lot on what period you choose. The longer the period, however, the more likely it is that stocks will come out the winner.

I also think it's important not to get caught up in the "recency" trap -- that is, let yourself be swayed too much by how any asset class has performed in the recent past. You're understandably chagrined by stocks' swoon back in 2000. Fine. That should give you a healthy respect for the downside to stocks and inform your investment strategy for the future.

But by avoiding stocks completely because of their collapse in the last bear market, you're acting more on emotion than reason. Those sorts of decisions rarely pay off over the long run.

So instead of getting your shorts in a knot about how lousy stock returns have been over the past five years, I suggest you check out some of the sources I've listed above and put your energy into building a well-balanced portfolio of stocks and bonds that makes sense given your investment goals, tolerance for risk and the length of time you'll have your money invested.

The future will always be uncertain. But at least you'll be facing it with a coherent strategy and a plan, a plan, a plan...

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