[kelnos]

I actually would suggest that, in many (most?) situations, someone may not know their value, and that's not a negative reflection on their professionalism. You can do all the research you want, but there are many situations where you can't discover enough of the company's pain points or match your skill set(s) to their needs to figure out what you are worth to them.

And even if you can do all that, there's no reason why the dollar value you put on your worth to them has to be similar to the dollar value they have in mind. You could argue, in that situation, that you may not want to work for a company that doesn't value you "properly", but I hesitate to believe that there's always (or even often) an objective version of "properly" that disinterested observers could agree on.

Having said all that, I am still not sure I buy into the idea that the best negotiation tactic is to evade (even "professionally") providing a number.