SEO knowledge
- known
things we know about google: technology docs, google guidelines, snippet structure
- maybe known
things which SEOs think must be true as every successful site is doing it: best practices
- known unknown
things we know that we don't know: ranking factors, basically every question that starts with "how important is ..."
- unknown unknown things SEOs do not know that they don't know: a unbelievable shitload of things
- deprecated known
things that were propably true once, but are (unknown) deprecated by now
there are basically two ways SEOs deal with this very shaky knowledge base:
1) magic number SEOs
they combine unrelated figures (and most of the time already very unreliable figures, most of the time based on very small samples of the internet) into magic numbers and then try to tell you something about your business based on these magic numbers
2) feel good SEOs
they tell you nice stories a la: "create good content and then the users will love your product, link to you and your rankings/traffic/pagerank/... will explode" which leave you with a warm feeling inside, but zero added value.
if SEO wants to stay relevant 5 years down the road the SEO practitioners (SEOs) must find a way to overcome the inherent knowledge issues of SEO and most of all, find a better way create value for the webproperties they work for.