Logical Fallacy Alert! http://en.wikipedia.org/wiki/Argument_from_ignorance
I don't know how to build a rocket ship nor to do a heart transplant, but I'm fairly confident that these are both feasible.
Moreover, you prove your own point - the one I was agreeing with initially out of everything said in this thread. A rocket ship or heart transplant are specific solutions to specific problems. The analogy to intelligence would be one universal solution to flight or one universal solution to getting oxygen and glucose into cells. It's not that a solution isn't possible. It's just that the hope for THE solution is misguided (see also THE cure for cancer).
I really like the flight analogy because of the length of time people put into finding THE solution. But what we end up with instead are rockets, and prop planes, and jet engines, and airfoils, and gliders, and helicopters, and hoverboards...
I see lots of specific solutions to specific problems. That, to me, is the best approximation of intelligence. To the extent that many specific solutions can be approximated and optimized, we'll be very well off. It's easy to denigrate a calculator and spell-checker, but I seem much more intelligent than I would be without them.