 Because Łukasiewicz was involved in government until the end of 1919, it took until 1920 for his discoveries of 1917 to be revealed to a wider academic public. Łukasiewicz returned to the subject of determinism for his inaugural lecture as Rector of the University of Warsaw on 16 October 1922. That lecture, delivered without notes but later written down, was reworked, though not in essentials, up until 1946. It was published only posthumously in 1961 as “On Determinism”. Distinguishing logical from causal determinism, Łukasiewicz claims that if a prediction of a future contingent event such as an action is true at the time the prediction is made, the event must occur, so the only way to rescue the agent’s freedom of action is to deny that the prediction is true, and assign it instead the third truth-value of possibility.