Suppose it were known, by someone else, what you are going to choose to do tomorrow. Wouldn't that entail that tomorrow you must do what it was known in advance that you would do? In spite of your deliberating and planning, in the end, all is futile: you must choose exactly as it was earlier known that you would. The supposed exercise of your free will is ultimately an illusion. Historically, the tension between foreknowledge and the exercise of free will was addressed in a religious context. According to orthodox views in the West, God was claimed to be omniscient (and hence in possession of perfect foreknowledge) and yet God was supposed to have given humankind free will. Attempts to solve the apparent contradiction often involved attributing to God special properties, for example, being "outside" of time. However, the trouble with such solutions is that they are generally unsatisfactory on their own terms. Even more serious is the fact that they leave untouched the problem posed not by God's foreknowledge but that of any human being. Do human beings have foreknowledge? Certainly, of at least some events and behaviors. Thus we have a secular counterpart of the original problem. A human being's foreknowledge, exactly as would God's, of another's choices would seem to preclude the exercise of human free will. Various ways of trying to solve the problem – for example, by putting constraints on the truth-conditions for statements, or by "tightening" the conditions necessary for knowledge – are examined and shown not to work. Ultimately the alleged incompatibility of foreknowledge and free will is shown to rest on a subtle logical error. When the error, a modal fallacy, is recognized, and remedied, the problem evaporates.
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