Presumption of culpable mental state shifts burden to accused to prove absence of the required mental element. In prosecutions under the Act requiring a culpable mental state, the court shall presume the existence of that mental state, but it is a defence for the accused to prove absence of such mental state. Culpable mental state includes intention, motive, knowledge, and belief or reason to believe a fact. A fact is proved only when the court believes it exists beyond reasonable doubt rather than by a preponderance of probability.