Tansey wrote a good, solid reply, but I dislike worshipping at the altar of mysteriousness. When a human or better GAI finally gets built, it won't be entirely hand-coded (although the seed for it might be). But the better we understand how our AI works, the better we can make sure it's doing what we want it to; and not, say, crashing the stock market with millions of erroneous transactions carried out too fast for humans to correct.