Rene Descartes asserted in the 17th century that human beings have free will. Unlike automata they are the authors of their actions and can rightly be praised or blamed for them. A century later David Hume said that human actions are determined with the same necessity as are events in the natural world and set about reconciling liberty and necessity. This debate has been continuously pursued by philosophers of the modern period who argue variously that the issues cannot be reconciled or who assert, as in the case of behaviourism, the primacy of necessity. Antony Flew and Godfrey Vesey share the view that agency and personal responsibility are vital in the debate but disagree profoundly about how this claim can be defended and on what grounds it has priority. Did Hume err in being an empiricist (Vesey's line) or in not being an empiricist (Flew). Is determinism wholly false (Flew) or neither true nor false (Vesey). The development of this disagreement is informed by an awareness of the contributions of philosophers from Plato and Aristotle to Wittgnestein and Strawson.