The use of predicate and sentential operators to express the practical modalities -- ability, control, openness, etc. -- has given new life to a fatalistic argument against determinist theories of responsible agency. A familiar version employs the following principle: the consequences of what is unavoidable (beyond one's control) are themselves unavoidable. Accordingly, if determinism is true, whatever happens is the consequence of events in the remote past, or, of such events together with the laws of nature. But laws and the (...) remote past are not under our control and, by the principle, neither are their consequences. Therefore, none of our choices and actions, nor anything that results from them, is under our control.1 Whether refinements of the closure principle underlying this unavoidability argument are acceptable depends upon the precise sense of 'consequence' and 'unavoidable' involved. Roughly, a proposition P is a consequence of a set of propositions M iff it is impossible that P be false when each member of M is true, or, conversely, when M necessitates P. Since P is unavoidable for S when P is true and S is (was) unable to prevent P from being true, it might seem that if P is unavoidable the same should hold of what is necessitated by P. There is, in fact, 1 an easy defense of the principle which utilizes the incompatibilist condition that S is able to do action K only if it is as yet undetermined whether or not S will K. With it, there is no question but that one is unable to accomplish what is already determined by what one was unable to prevent. Of course, this reasoning is unlikely to impress the compatibilist who rejects the condition outright and, expectedly, it is not the procedure of the proponents of the unavoidability argument. The latter might rest content with appeals to intuition, but more significant are defenses of the closure principle and independent derivations of the unavoidability argument that rely upon distinct principles concerning the logic of the practical modalities, for example, closure of ability under entailment (Cross 1986, Brown 1988) or, claims about the "fixity of the past" and the "inescapability of laws" (Ginet 1990).. (shrink)

This paper argues that, with certain provisos, predicting one's future actions is incompatible with rationally deliberating about whether to perform those actions. It follows that fully rational omniscient agents are impossible, since an omniscient being could never rationally deliberate about what to do . Consequently, theories that explain practical reasons in terms of the choices of a perfectly rational omniscient agent must fail. The paper considers several ways of defending the possibility of an omniscient agent, and concludes that while some (...) of these may work, they are inconsistent with the aim of explaining practical normativity by appeal to such an agent. (shrink)

This paper argues that, with certain provisos, predicting one's future actions is incompatible with rationally deliberating about whether to perform those actions. It follows that fully rational omniscient agents are impossible, since an omniscient being could never rationally deliberate about what to do. Consequently, theories that explain practical reasons in terms of the choices of a perfectly rational omniscient agent must fail. The paper considers several ways of defending the possibility of an omniscient agent, and concludes that while some of (...) these may work, they are inconsistent with the aim of explaining practical normativity by appeal to such an agent. (shrink)