**Johannes Schmidl**

Save Energy Austria, Franz Josefs Kai 13/12-13, 1010 Vienna, Austria; johannes.schmidl@chello.at Received: 8 January 2020; Accepted: 11 February 2020; Published: 16 February 2020

**Abstract:** The discussion of whether or not humans are able to act freely is ongoing, even though, and precisely because, technical methods for detecting the physical state of the brain are constantly improving. The brain as a physical–chemical object seems to be pre-determined by its physical and chemical states, while at the same time human consciousness gives the impression of being able to decide subjectively and freely on its own. Determinists claim that this free decision is just a form of misinterpretation of an epiphenomenon and that the alleged "free decision" has actually been determined by the physical state of the brain before the human subject gives the impression of being able to decide freely. The basis for this is a set of experiments, the first of which was specified by Benjamin Libet. Determinism, as the philosophical position that all events are entirely determined by previously existing causes, in principle enables the existence of a perfect predictor. In this paper, a thought-experiment is introduced which demonstrates that a subjective consciousness can break any forecast about its physical state, independently of the method of its detection, and, consequentially, to refute claims about its purely deterministic role. The thought-experiment picks up on an idea of the philosopher Alvin I. Goldman. Logically, the proof follows the path of a 'reductio ad absurdum'.

**Keywords:** thought-experiment; libero arbitrio; freedom of will
