Before discovering Objectivism, I used possible to mean “something that has not been demonstrated to be contradictory with known truths” and impossible to mean “something that has been demonstrated to be contradictory with known truths”. Objectivism, however, holds that some evidence is required for something to be deemed possible. For example, I would have said that gremlins are theoretically possible (although arbitrary), but Objectivism does not. It regards the two as mutually exclusive.
Recently I was having a discussion with a friend about God. She agreed with me that God is arbitrary and that many conceptions of God are metaphysically impossible. However, she holds that the conceptions of God which are not metaphysically impossible (e.g., a creator that abides by the laws of reality) are still possible. And so it seems that she used possible in the way that I had before. How would one demonstrate that this usage is wrong and the Objectivist usage is correct?
Lastly, I have a related question about the supernatural. Searching the forums, it seems that Objectivists have defined the supernatural as “apart from/above reality”, i.e., conflicting with reality. But witches and goblins, which are often classified as supernatural, aren’t impossible, just arbitrary. So why is the supernatural defined as such? Are there two different concepts of “supernatural”, one being more philosophical?