In this paper, we show that a restricted form of time travel both accords with special relativity kinematics and avoids several prima facie objections. We argue that such time travel provides a reasonable way to interpret certain phenomena which can readily be described, and the analogues of which have already been observed at the level of elementary particle reactions. We then describe how a time-traveling object could measure itself, and demonstrate how, in the appropriate circumstances, such an experiment could convince (...) a theorist who insisted on a single criterion for length measurements that his standard had itself changed in length. The same experiment can shed light on the possibility of detecting a universal expansion; and we show that, given certain experimental results, one must conclude that every member of a class of time travelers has changed in length simultaneously, though perhaps only while going backwards in time. (shrink)

Do analogical models ever play an essential role in scientific explanation and confirmation, or is their role (at most) heuristic? For many years scientists and philosophers have debated this question. I argue that such models may sometimes play an essential role. My argument is based on a proposal to augment Goodman''s theory of projection in order to make it easier for novel predicates (extensions) to acquire entrenchment. The heart of this proposal is the claim that analogical models may, under certain (...) conditions, be the medium whereby entrenchment is passed from well established predicates to new and unfamiliar ones. (shrink)

Beginning with an analysis of the "reluctant gambler problem"—in which the notion of guiding one's life by probability seems to conflict with the preferences of rational people—we draw a distinction between rule and act probabilism. Arguing that humans are rule probabilists by default, we show that reluctant gamblers can be viewed as rule probabilists. If so viewed, their reluctance to gamble is consistent with their rational use of probability judgments to guide their lives.The distinction between rule and act probabilism suggests (...) a way to analyze the risks stemming from the September 11 terrorist attacks. Assessing the risks posed by the new reality of terrorism in the U.S. in light of the rule versus act probabilist distinction shows the risks Americans face from a terrorist attack are essentially the same as they were before September 11, 2002. Yet empirical investigation indicates Americans exaggerate their personal risks from terrorism.The perception that the risks of terrorism mushroomed on September 11 is partially explained by the 24-hour news stations' TV coverage and the current administration's "interest" in diverting attention from their own questionable practices. While the risks of terrorism are not appreciably higher than they were prior to September 11, they might be further reduced. Unfortunately, our government's strategy to reduce the risks of terrorist strikes involves weakening the Constitution. Americans face the question how much it is appropriate to pay—in diminished rights and liberties—to reduce a risk that is essentially the same as it was prior to the attacks. (shrink)

On the assumptions that omniscience is knowledge of all facts and that knowledge is some species of non-accidentally true belief, I construct an argument that no being is omniscient. Any omniscient being would have to know its own omniscience, but there appears to be no way for that to be known, whether for a being who is supposed merely to be omniscient, but otherwise unremarkable, or for a being with the full panoply of theistic attributes normally supposed to accompany omniscience. (...) The argument is premised upon assumptions about knowledge and omniscience that appear minimal and mostly non-controversial. Therefore, it is reasonable to believe either that no being is omniscient or that even the apparently minimal assumptions are problematic. (shrink)