Molly: A guy who I met at a party has just invited me to join Facebook and become his 153rd “friend”. Clearly I'm going to have to blank him.

Tad: Why, what was wrong with him? Did he have an unbroken pelt of hair from his forehead to his feet? Did he speak only in rhyming couplets? What?

Molly: I just hate Facebook. It's such a lame way of getting in touch.

Tad: It's just another way of being sociable.

Molly: Maybe if you are 14 and can't afford to use the phone it is. But this guy has been married and divorced. And do you honestly think that he just wants to be friends?

Tad: Well, if he's very brave, I suppose there's an outside chance that he wants to get into your pants.

Molly: Then even more reason simply to ask for my phone number like a grown-up. I can just about forgive Facebooking in a woman trying to be encouraging without looking pushy. But in a man it strikes me as limp - the sort of approach that only a rubbish kisser would resort to.

Tad: Maybe he's shy. Maybe he didn't have a pen. Maybe he didn't know you had an irrational hatred of social networking websites.

Molly: Surely you can see that a relationship that begins with “Our eyes met across a crowded room” beats one that starts “He poked me over a glorified internet chat room”?

Tad: The alternative might be “And I never saw him again”. Facebooking is perfectly harmless.

Molly: But is it? Surely the harmless thing to do would have been to call or even send a friendly e-mail. Instead, he has directed me to a forum where I can check over the minutiae of his life. That's like being invited to see his etchings, read his diary and look through his holiday snaps before I've even agreed to a first date. Maybe Facebook shouldn't list its subscribers' “friends” so much as individuals they either plan to, or already have, seduced.

Tad: I hope not. I've got my aunt and uncle on my friends list.

Molly: Aha! So you are on Facebook, then. I'm now doubly convinced that social networking sites aren't really about friendship at all.

Tad: Who said they were? Social networking sites are the modern-day answer to the 19th-century collector's display case of curiosities.

Molly: I'd say they are a stalking mechanism for sexual predators and their prey.

Tad: That too. But where you find fault, I see merit. Facebook is a cheap alternative to hiring a private investigator. Once you're “friends” with someone, you can look at their photos, see what they've been up to and who they were touching while they were doing it.You can also check who their friends are and generally vet a potential love interest.

Molly: But people normally only resort to using private investigators when a relationship has failed and they can't let go. I wonder how many Facebookers torment themselves by checking out what their exes are up to? It can be addictive and harmful.

Tad: So can alcohol, but I wouldn't want to live without it. I do worry about friends who spend an inordinate amount of time posting videos of elephants shoving their trunks up other elephants' backsides. But every now and then someone who you're genuinely excited about contacts you - a girl you met at a bar, maybe, or an old friend you haven't seen for ages.

Molly: At which point you presumably read their profile page - invariably a ludicrously upbeat account of their life. That's the other thing that annoys me about it. Where's the bad news? The nights that didn't go off with a bang? Has anyone ever claimed to be anything less than off their head with joy on their profile? It's so dishonest. On Facebook, you have to keep your personal brand inanely sunny at all times.

Tad: Not something that I could ever accuse you of, Molly.

Molly: A compliment at last...

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