That depends. If you already know the person, then chances are that you're either friends or you work together. Dating either one, in your doctor's humble opinion, is a recipe for disaster.

Oh, sure, there are good points, like not having to come up with a witty opening line or explaining what you do for a living or going through the awkward getting-to-know-you process, because they already know all these things about you. But there are negatives. Trust me on this, folks. I've done it.

Let's assume that you've known Mary (or Larry) for years and you're comfortable around each other. If you start dating, you're putting the existing relationship at risk. Touchy situation: Do you really want to risk losing a friend?

If you decide that it's worth the risk, that's not the end of it. Now you've got your other friends to worry about. Everybody who's known her as your friend and you as her friend has to get used to the two of you ... well, not being friends. That's not really such a major problem but it does make things a little weird.

But let's assume that your friends have accepted this budding relationship without giving you too much grief. Now things are different between you and Mary (or Larry). Suddenly you're seeing a lot more of each other than you did before, and in a different way. You're each feeling responsibilities that you didn't before. That's not such a bad thing, but it's different from what it was before. Maybe it makes one of you uncomfortable. Maybe now somebody's noticing little quirks, like the way she eats her spaghetti or how you're always five minutes late, and it's getting annoying. Somebody's starting to want out.

Dating is a hazardous business that leaves plenty of wrecks along the highway to True Love, and friends are kind of like Travelers’ Assistance Centers along that road. If one of your friends becomes one of the wrecks, that's one less friend you've got to see you through. I think that's too high a price to pay, because dating is transitory (until you meet the right one), while friends are forever. Maybe you can be friends again, but probably not.

Dating your co-workers is risky business too, because now you're messing with your paycheck. Again, it's got its good points, but it can be even worse than dating a friend. You get to see them every day. Nice, isn't it? You can have lunch together and leave together after work and stop by their workspace to say "hi." But the boss probably doesn't like it. Because now it's affecting your work.

You're taking long lunches and calling each other several times a day and taking long coffee breaks together, and you're just not as efficient as you used to be. Your co-workers are gossiping about the "new couple" and they're taking long coffee breaks to talk about what you're up to. If you're trying to keep your new relationship a secret, then all of that is happening and you're devoting still more energy to keeping it under wraps. And everybody knows anyway, which means they're gossiping even more.

But so what? What if you're still the efficient, well-oiled machine you used to be and everybody takes this in stride? Well then, more power to you, I hope it works out. But if it doesn't, things are going to get very weird very quickly.

Now you're thrust into facing this person you’d rather not see every day and there's no escape. You're in the same place together, five days a week, and there's no way to miss them short of using all your vacation and time. And that's eventually going to run out and you'll still have to face them. Unless you're incredibly mature and reasonable about it – and no one ever is -- messy confrontations are going to happen and your work is really going to suffer. The only way to solve the problem if for somebody to quit -- or to get fired. And that means somebody loses a paycheck and a job they probably liked.

All that, just for a grab at the brass ring. At least when dating your friend blew up in your face you got to keep your job. Nope, it's too risky and too prone to failure. That kind of day to day pressure and exposure only works in established relationships, and even then it's kind of iffy. My advice? Skip it.

But, hey, I could be wrong. The great love of your life could be at the next cube or in your address book already. Who am I to say? You've got to use your best judgement and hope for the best. Maybe it'll work. But if it doesn't... Well, if it doesn't, it's even worse than dating a stranger because you walk away emptier.