Presumption of culpable mental state shifts burden to accused to prove absence of such state beyond reasonable doubt. The Act presumes the existence of a culpable mental state in prosecutions requiring it, while allowing the accused to defend by proving absence of that state; 'culpable mental state' covers intention, motive, knowledge, and belief or reason to believe. A fact is regarded as proved only when the Court believes it exists beyond reasonable doubt, not by a preponderance of probability.