Many breeds of professional have been mighty busy coping with digitally-driven changes over the last decade or two: journalists, musicians, travel agents, PR practitioners, job recruiters...

Let me suggest one more group of people who must be learning to live their lives in constant flux: ethicists.

The web has redrawn a lot of ethical boundaries over the past few years. The ongoing debate over Michael Arrington and whether journalistic ethics from the pre-Internet era should apply today is only the latest in a flood of dilemmas, quandaries and fine-how-do-you-dos. And every time I start thinking something's nice and simple on the ethics front, a new wrinkle emerges.

One issue I'd thought had been settled long ago involves the ethics of email marketing. I'd thought the day had been carried long ago by supporters of double-opt-in: where you sign up on a web site, then click a link in an email to activate your subscription. That's as opposed to single-opt-in, where you submit an email address, and the flow of thinly-disguised ads valuable information begins. Or zero-opt-in, which is more commonly known as spam. (Unless you have permission through some other channel. No, "vibes" or "a feeling they'd like to hear about this great offer" don't count.)

It turns out I was wrong: single-opt-in still has its loyal partisans. Their core argument often boils down to convenience and effectiveness in list-building: many people never click that confirmation link. Then again, it's hard to say how much of that is because people miss the confirmation emails, because they can't be bothered clicking... or because someone submitted their email address without their permission. (More on that in a sec.)

You could see that argument as self-serving: "because it improves my metrics" doesn't exactly radiate moral suasion. But the flip side is convenience for the subscriber: being able to sign up for something with a minimum of fuss and bother.

Problem is, there are plenty of people (and bots) plugging fake or unauthorized email addresses into sign-up forms. I know, because I see it happen on my company's own newsletter form... and because I keep seeing email marketing pieces from reputable companies piling up in our catch-all email account, with made-up user names. And for a user who has been signed up without their knowledge, there isn't much difference between receiving a piece of single-opt-in email and spam.

Which means a new ethical question: does convenience for the users who want to subscribe outweigh the inconvenience to those who get signed up involuntarily?

Complex, no? And yet from these conflicting arguments and competing moral positions, one crystal-clear conclusion emerges: If you want a job with real growth potential, you could do a lot worse than becoming an ethicist.

See more Noise to Signal cartoons here.