Hmmm, I'm inclined to both agree and disagree.
There's certainly a science behind
SEO's more minute details and it's probably something you could learn about forever without ever knowing everything that there is to know - particularly as the algorithms, rules and goalposts change all the time.
Having said this, you can learn as much as most people
need to know in a fairly short period of time, IMO. Particularly if you already have a good understanding of Web design and/or development.
A lot of
SEO's try to convince people that they're masters of some kind of black art that the rest of us don't get and that there's no way we could encroach on their precious ground. But the truth of the matter is that
SEO, for the most part, is just an extension of Web design/development, with an additional knowledge of how
SE's work. And 2% of the knowledge makes up for 98% of the effectiveness of a good
SEO campaign. You can learn loads, you just don't need to.