"I said at the start that I didn’t believe in miracles. That’s true. PK appears to work with the laws of physics, not above them. My biggest achievement was spinning a small piece of aluminium foil suspended on a point, beneath an upside-down glass bowl.iii That doesn’t sound impressive until you record the apparatus for seven days straight and observe that the foil definitely doesn’t move on its own, despite changes in light, temperature, airflow and electromagnetism.iv Furthermore, successful PK is sometimes accompanied by unusual physiological sensations in the body, confirming a direct causal connection between the intention of the person and the movement of the object."
How can you be sure, if you are sure, that this movement was caused by PK as opposed to an observing spirit - the Ouija board idea?