Admittedly, this has been for the most part a semantic argument, but clearly one that many of us feel strongly enough about to keep the dialogue going. It seems that there are some who believe that performing a design activity qualifies one as a "designer", no matter how infrequently or successfully. I believe this is a matter of interpretation, and I'm willing to say why I think that interpretation is flawed.
But first, here's what I think a "designer" is.
A designer is one who performs design activities as a primary part of his or her vocation or profession. An architect is a specialized kind of designer, using recognized methods to create a plan for constructing a building. It is not necessary for someone to derive income from there activities to be considered a "designer", but most "designers" do make money at it. There are students who are designers, performing design activities in pursuit of their degree or certification.
A specific degree is not required to be a designer. Probably more than half of the Interaction Designers I've met do not hold a degree directly related to design. A designer is usually distinguished by some measure of training or experience, but only becuase those are usually the terms of having a vocation that includes design activities.
Meeting my criteria for being called a designer does not imply any measure of quality. I know designers with plenty of experience and long resumes who are plain awful...but they're still "designers", just bad ones.
Here are some examples of people who I believe are not "designers".
An account manager who contributes ideas to the design of a product is not a "designer". She may have great ideas and a well-developed design sensibility, but she is an Account Manager. That is what she is expected to do by her peers, that's what it says on her business card, and that's what role her client expects. No matter how much she contributes to the design of the product, she's not a designer until it's a primary part of her vocation.
The hobbyist or volunteer who designs the flier for the church picnic is not a "designer". He may have chosen the font and laid out the text, but he's a tennis pro by trade, or an investment banker...maybe both.
And now, why I think this is an important discussion.
We can all think of semantic analogies on both sides of the issue. I would never call myself a "singer" just because I yodel in the shower, but I might call myself a "skier" even if I only go once a year (and am no threat to make anybody's Olympic team).
But the context of the discussion is the real issue. Take the example above...I might say to a co-worker that I am a skier, but I would certainly not call myself a "skier" in the company of the Austrian Winter Olympic team.
Here we are, design professionals, saying that the mere act of scribbling a shematic on a napkin makes one a designer...and among our own brethren! It's a dangerous precedent, and I suspect that many of the people who've spent years battling for the credibility of their trade (like myself) feel that this facile definition denigrates our profession.
It's absolutely true that anyone capable of the basest form of communication can contribute to a design. But when that becomes the price of admission to being called a "designer"...call me something else.
Of course, this is just my weltanschauung. To each his own.