Technology critics like Nicholas Carr often complain that the Internet is hampering our ability to think. Facebook, and even more so Twitter, exemplify this trend.

Back during the ancient days of my youth, when dinosaurs roamed the planet, and shortly after fire was invented, I would communicate with my Stanford friends over the summer by (gasp) writing letters. As hard as this may be for some of you to believe, I would sit down with a pen and paper, and write out a lengthy message, usually over several pages–hey, if you’re going to go through so much trouble and pay $0.25 for a stamp (yes, stamps cost that little then), you might as well get your money’s worth.

By doing so, I was tapping into an epistolary tradition that goes all the way back to antiquity, and one which still generates sales for things like “The Collected Letters of Edgar Allen Poe.”

Today, however, I suspect that people keep in touch with their college friends via Facebook and Twitter, with short messages and quick quips being the rule of the day.

And while this enables more frequent and casual conversation, I can’t help but feel some agreement with the Carrs of the world–something is being lost, and I don’t think I’m going to feel the same satisfaction picking up a copy of “The Collected Tweets of Scobleizer.” (No offense, Robert! You’re a great guy, but you’re no Edgar Allen Poe. Then again, what the hell did Poe know about social networking?)

What’s being lost is focus. Want an example of the power of focus? Think about how much you get done when you’re on a long plane flight.

The work conditions are awful–you’re stuck in a cramped, far from ergonomic seat. The tray table bangs into your knees, and if you have a 14″ laptop like me, it barely fits, even with my elbows glued to my sides. There’s a constant drone of engine noise, punctuated by screaming babies and random announcements.

Yet I find that I can get more done on a cross-country flight than just about anywhere else.

The key is focus–that horrendous environment offers few distractions to tempt me away from the matter at hand. I’m literally belted in and unable to move, and the process of visiting the lavatory (without tampering or disabling the smoke detectors) is so arduous that I avoid it as much as possible. I have no choice but to focus.*

* This effect is so strong that I’m considering rigging up a closet as a workspace–just enough room to sit and work, no windows, no distractions. And cheap too!

And that is the truth behind Carr’s argument. The Internet is a good thing. Having the collective knowledge of humanity a single search away is a good thing. Staying in touch with the people in your life is a good thing. But as my youthful letter writing and the cross-country flight effect demonstrates, sometimes constraints provide a discipline and motivation that choice does not.

But while Facebook and Twitter are bad for focus, they are very good at providing something else which is just as important: Serendipity.

Creativity and insight often come from the unexpected, and few things provide better raw material for serendipity than the massive firehoses of data that are our Facebook and Twitter feeds.

Through these tools, I can follow the activities of far more people than ever before. I’ve made tons of great discoveries through these tools. For example, if I hadn’t set up a Conversely Twitter group for my HBS class, I never would have discovered that my old classmate Lindsey Mead has jettisoned the corporate world to focus on her writing, and is producing intensely introspective and fascinating work. After seldom speaking during our two years in school, we’re now corresponding on a regular basis.

The same holds true for business as well. As my friend TK puts it, “I know that whatever I need to know or do, Chris has a contact that can help.” I’m far from a professional networker. But as I’ve noted before, simply meeting and staying in touch with interesting people tends to produce good results. Serendipity + Persistence is a powerful combination.

And so we face a paradox; technology makes us smarter by providing more opportunities for serendipity, but technology makes us dumber by impairing our ability to focus.

As usual, the answer lies in Aristotle’s Golden Mean. Both focus and serendipity have their place, and we need to take advantage of both by alternating between the two.

Friend and follow away on Facebook and Twitter, and let the stream of serendipity wash over you. But don’t forget to book that flight to Singapore (or empty out that closet in the hallway) so you can refine the raw material of serendipity into something original and powerful through the application of focus. The two concepts should feed into each other as yin and yang to produce a whole that is greater than the sum of its parts.

Which reminds me…now that I’ve put in 30 minutes of focus on this post, time to hit Hacker News Daily for some serendipity!