Just in case readers don't know what I'm up against in arguifng the bullish case for BlackBerry maker Research In Motion (NASDAQ:RIMM), let me paint a picture for you.

Let's see. Back in May, fellow Fool Rich Smith noted that an overwhelming contingent of CAPS investors thought RIM was ready for a big fall. Then, less than six months and nearly 150% later, Fool value guru Philip Durell gave a well-reasoned argument as to why RIM is the scariest stock in the world, with shares trading at $122. All this adds up to a stock that has already risen so far, it can't possibly go any higher. Or can it?

It all seems so simple
In all honesty, it's not hard to make a bear case for Research In Motion (RIM) with as little as 30 seconds of analysis. A whopping current earnings multiple of 66 stands out. Operating in the fiercely competitive and fickle market of wireless devices doesn't give warm fuzzies, either.

My bearish-minded counterpart Anders Bylund will no doubt have a full range of artillery in his arsenal as well. But the company has been the target of these same criticisms for years. And all the arguments for how the stock is too expensive and competition will soon devour it haven't kept the stock from returning a staggering 4,448% in the past five years.

While I understand an argument can be made for seeking out good, cheap stocks ahead of expensive ones, I also recognize that this approach kept investors out of a market leader 1,000% ago. And 2,000% ago.

Maybe it's not so simple after all
For an investor looking at RIM today, let's go right to the heart of the two most important points to consider: sustainability and valuation.

In terms of sustainability, investors and analysts constantly worry about competitive pressures slowing or eroding RIM's market position. Initially, competition from Palm's (NASDAQ:PALM) Treo lineup was supposed to have BlackBerries collecting dust on the shelves. Then the Apple (NASDAQ:AAPL) iPhone was predicted to lay waste to all other smartphone options. Neither of these, nor cellular phone leader Nokia (NYSE:NOK), have yet come up with a single device, let alone an entire platform, that can put a dent in RIM.

Meanwhile, RIM has successfully launched a fleet of BlackBerry devices eagerly received across both the business and consumer markets. This has led to a dominant position in the North American market, with carriers such as AT&T (NYSE:T) and Verizon (NYSE:VZ). Take a look at how this success has translated into RIM's 12-month revenue and subscriber base growth:

Q2 2005

 Q2 2006

 Q2 2007

 Q2 2008

Revenue (billions)

$0.94

$1.71

$2.39

$4.22

Subscribers (millions)

1.66

3.65

6.2

10.5

Revenue data reflects trailing 12 months for named fiscal periods.

But RIM could falter in the future, you say. The iPhone is only getting started, and Google's (NASDAQ:GOOG) Android may start to squeeze out proprietary platforms such as the BlackBerry. But these arguments assume that the smartphone market is bounded, where market share gained by one player must be countered by another's loss.

Not so. The total size of the market is expanding rapidly. Nearly a billion cellular phones were sold in 2006, and Gartner predicts a double-digit increase to about 1.13 billion in 2007. According to research firm NPD Group, smartphones like the iPhone and BlackBerry made up 11% of mobile sales in the third quarter, a portion 163% higher than last year. The iPhone and others aren't crushing competitors -- they're adding to the total market, and they may even be boosting RIM's sales in the process.

Overvalued or invaluable?
In terms of RIM's valuation, one thing is clear: The stock will never be cheap. The amazing growth and popularity of BlackBerry will ensure that. But amazing stock stories do exist, where companies continue to exceed all imaginary bounds investors and analysts place on them. RIM has never been a value play and never will -- because the size and gravity of its market cannot be accurately predicted.

So what does it take to take a $60 billion company with a P/E of 66 even higher? Flawless execution? Nope. RIM has had plenty of operational stumbles in its recent past, and still manages nearly 70% growth in recent years. If you're inclined to avoid RIM because you believe the stock is priced for perfection, you might want to read this.

So the next time you doubt RIM's possibilities, consider that it's been in the same position time and again and came out on top each time. Sure, it won't be easy to double from here, but the innovator is only now starting to tap large international and consumer markets that have yet to experience the BlackBerry platform.

You're not done yet! Check out the other articles and then vote for the winner!

As Foolanthropy enters its second decade, join us in working to bring financial education to the world's children. Learn more about Foolanthropy's new direction.

Fool contributor Dave Mock still enjoys an occasional PB&J. He owns no shares of companies mentioned here. Dave is the author of The Qualcomm Equation. Palm is a Stock Advisor recommendation. The Fool's disclosure policy knows no bounds.