"I know you!"
These words are used differently. You cannot use 知道 here.
知道 is to know a piece of fact (not necessarily a simple one)
认识 is to know about sb/sth from several aspects, or to a certain depth.
He knows about archaeology.
He knows how Egyptians built pyramids.
认识 also means to learn but 知道 doesn't.
Let's learn how Egyptians built pyramids.
Also, I found an answer.
Both 4th and 2d tones are used for this, here is an explanation [it is russian]: http://www.zhonga.ru/chinese-russian/%E8%AF%86/a7h1b