  Imagine you are in court accused of murdering your boss. The evidence against you: you were heard shouting at you boss and saying I'm going to kill you the day before the muder, you have no alibi, you were seen in the area around the time of the murder, the murder weapon belonged to you. However, you know that you were not the person who committed the murder because you can remember what you did and it wasn't murder, but you have no proof to present in court.  How is that person supposed to make a subjective distinction between perception and guessing?  