I feel that in order for anyone to get a good grasp of what this branch of science actually encompasses, one must make a lists of what they feel “exists” and “doesn’t exist”. I recommend making a list of what you honestly feel at this point exist and what you feel does not exist. For instance, if you believe in “ghosts,” then add ghosts to your list. If you believe in “God, or a God,” then add it to your list. These things which are being added to your list can either be something material, something non-material, or even a hypothesis (something you believe to be real but has not yet been proven.)