You make a number of assumptions here and you also ignore my previous comments regarding the following point: you assume that knowledge of one's source code permits a fundamentally more powerful kind of recursive self improvement. This is a crucial assumption on which your argument rests... if this assumption is false (and it is certainly insubstantiated) then we have no reason to believe that a GAI can do any more than what a human can do, given full knowledge of the brain. And as we know, there are some serious limitations on what we can do with the brain. Thus the concept of recursive self improvement leading to super-human intelligence is equated to (essentially) the problem of drug and surgical treatment and expansion, which has a rightfully limiting sounding ring to it.
Furthermore, your assumptions consist in (for example) the idea that such a thing as the agent you describe can possibly exist. It is all well and good in theory to talk abstractly about a system (e.g., a human) improving its intelligence to improve its intelligence, but you seem to draw a kind of arbitrary distinction between this process and the more common processes involves in human activities, like piano playing.
In the piano example, you are just incorrect to claim there is no recursive self improvement (RSI, now) going on there. Just consider the following ideas.
Specifically, you point out that pianists don't actively seek to recursively self-improve, which is true, as it would be hopelessly convoluted and they would never learn how to actually play anything. However, you neglect to consider the passive action of recursive self-improvement which takes part in the process. This action is clear from the simple observation that an experienced pianist can learn (i.e., sight read a new piece and play it) much better than a beginner pianist. Since learning pieces is exactly what makes you a better pianist, this is an empirical evidence of recursive self-improvement. It is besides the point that this may not be the same degree as your idealized RSI, which is an arbitrary, impractical, and undemonstrated mode, as pointed out above. It is also besides the point that the pianist doesn't actively seek out this technique. (Even if a GAI didn't actively seek out to RSI its "intelligence", but it still did, we would achieve the same end results. )
And as we know, there are some serious limitations on what we can do with the brain.
Yes, but imagine not only that we have complete access to the brain's source code, but that the brain is digitally implemented and any component can be changed at whim. What could we achieve? At the very least, some very helpful things, if not superintelligence:
We already have examples of drugs and diseases that boost cognitive performance. Personally, I've been hyperthyroid before. The cognitive boost at the peak was very pronounced. This can't be sustained in wetware (...
As promised, here is the "Q" part of the Less Wrong Video Q&A with Eliezer Yudkowsky.
The Rules
1) One question per comment (to allow voting to carry more information about people's preferences).
2) Try to be as clear and concise as possible. If your question can't be condensed to a few paragraphs, you should probably ask in a separate post. Make sure you have an actual question somewhere in there (you can bold it to make it easier to scan).
3) Eliezer hasn't been subpoenaed. He will simply ignore the questions he doesn't want to answer, even if they somehow received 3^^^3 votes.
4) If you reference certain things that are online in your question, provide a link.
5) This thread will be open to questions and votes for at least 7 days. After that, it is up to Eliezer to decide when the best time to film his answers will be. [Update: Today, November 18, marks the 7th day since this thread was posted. If you haven't already done so, now would be a good time to review the questions and vote for your favorites.]
Suggestions
Don't limit yourself to things that have been mentioned on OB/LW. I expect that this will be the majority of questions, but you shouldn't feel limited to these topics. I've always found that a wide variety of topics makes a Q&A more interesting. If you're uncertain, ask anyway and let the voting sort out the wheat from the chaff.
It's okay to attempt humor (but good luck, it's a tough crowd).
If a discussion breaks out about a question (f.ex. to ask for clarifications) and the original poster decides to modify the question, the top level comment should be updated with the modified question (make it easy to find your question, don't have the latest version buried in a long thread).
Update: Eliezer's video answers to 30 questions from this thread can be found here.