Supernatural means something that is not natural. In my book, if something is not natural, then something or somebody must have intervened from outside the natural order, which is where the supernatural or magic supposedly arise from. Yet, surely they know what they did, so that event has an explanation, and is therefore not magic?
Let's say we're in the past i.e. B.C. If I see a plane or something like that, some might consider it magic. However, we know now that there is a logical explanation. Logic does not change over time - it is constant. The logic behind a plane is the same now as it was thousands of years ago. Therefore, I would not consider that plane, in any time period, magic. As such, I think that magic can't exist since it must have a logical explanation, even if that explanation is beyond our grasp.
Definitions of magic vary from source to source, whether it's something that cannot be explained in the present and contradicts current science, or the interventation of beings from other dimensions (or whatever else is out there). Perhaps the thread starter would like to shed some light on the topic and give us his definition of magic? Otherwise, we would just carry on arguing about the actual meaning of magic, which would probably prove to rather pointless if we're arguing about two separate things!