I was watching part of a David Blaine rerun with a family member, and they asked me what kind of magic trick would convince me that said person was really "magic" as opposed to just being an illusionist.
On the spot I said that while I could be extremely "impressed" I concluded that no such task would be convincing, even things like blatant mind reading, causing all green plants to appear red for a day, or causing an interstellar image to appear.
The problem is that to consider something magic I have to say that what I'm seeing doesn't just appear to break the rules, but actually does break the rules. The rules being the rules of reality, the laws that govern the universe, or perhaps the laws of physics.
When one sees an illusionist perform an impressive trick they could have the following reactions:
1. I know all the rules, and what has just been done violates a rule and is therefore magic.
2. I know all the rules, however what I am seeing likely fits into these rules and only appears not to.
3. I don't know all the rules, but what I have seen certainly breaks the rules and is therefore magic.
4. I don't know all the rules, but what I have seen likely fits into the rules I do know, and only appears not to.
I find #4 the most pragmatic, as #2 has the problem in that if it can be shown that none of the rules are broken, they will either have to conclude that what they have seen is in fact magic, or conclude that they actually do not know all the rules.
#3 is illogical since how can you know that something breaks a rule if you do not know all the rules?
#1 is the main path to a belief in magic.
It's ironic that a magician such as David Blaine could go far back in time to early human cultures and do his magic tricks, and easily convince such early peoples that he has magic powers. Most wouldn't argue that such persons would be quick to believe in magic, and yet this is due to a belief that one understands their reality completely, as opposed to not understanding it.
While skeptics are often seen as arrogant know-it-alls, their position is one of accepted ignorance and uncertainty over the knowledge they possess.
This has implications of theism vs. atheism, since a deity would likely possess great 'magic'.
"Any sufficiently advanced technology is indistinguishable from magic." -Arthur C. Clarke