Recently, at an informal academic seminar, a colleague quoted the famous Rolling Stones line to the effect that, while "you can't always get what you want, if you try sometimes you just might find you get what you need."
I couldn't resist responding after the session with Dylan's take on the Want Versus Need issue: "Your debutante knows what you need, but I know what you want."
He struck back with earlier Dylan: "Go 'way from my window, go at your own chosen speed, I'm not the one you want, babe, I'm not the one you need." He called this classic regulatory command and control - apart from its leaving open the speed choice - since Dylan purports to know both what the other person wants and what she needs.
I responded that negative externalities and asymmetric information provide the classic rationales for regulation. Here, not only does Dylan evidently find her presence at his window irksome, but he also claims to know more about himself than she does (hence "I'm not the one you want / need"). Both claims are plausible.
Nonetheless, my colleague replied that this is just the usual public interest rhetoric disguising private rent-seeking. Perhaps he has a point, given that, while the Dylan of mid-60s love-hate songs is frequently compelling, he does not, thank goodness, come off as public-spirited like the earlier folksinger. ("Ah, but I was so much older then, I'm younger than that now.")