I will show how a metaphysical problem of Arthur Prior’s can be solved by a logical tool he developed himself, but did not put to any foundational use: metric logic. The broader context is given by the key question about the metaphysics of time: Is time tenseless, i.e., is time just a structure of instants; or is time tensed, because some facts are irreducibly tensed? I take sides with Prior and the tensed theory. Like him, I therefore I have to (...) deal with a more specific metaphysical question: How can the instants of tenseless time be reduced to tensed facts? This is the point where, on the technical level, hybrid logic and metric logic come in. For present purposes, both can be seen as species of tense logic; and both are creations of Prior. In his argument for the tensed theory of time, Prior used hybrid tense logic to reduce instants. But, as he himself pointed out, this reduction runs into deep problems, because it immediately generalizes to other categories, for example and most importantly to persons. My main aim is to show that metric logic does not run into similar difficulties: It will help the tensed theory reduce instants, but it leaves persons untouched. I will also give reasons for preferring a metric to a hybrid logic of time that are independent of the metaphysical issue of reduction, but concern temporal reasoning, natural language semantics, and the epistemic side of time-keeping. (shrink)

In diesem Aufsatz wird im Rahmen des Projekts einer Logik des Lebens die Ebene der Zellen und die Beziehung zwischen Lebewesen und Zellen behandelt. Es werden die Beziehungen "ist Zell-Vorfahre von", "ist Zelle von" und "ist Zelle desselben Lebewesens wie" untersucht. Postulate für Lebewesen werden umgedeutet und auf die Zellebene übertragen. Es werden Möglichkeiten diskutiert, die Vorfahren-Relation für Lebewesen auf der Grundlage der Vorfahren-Relation für Zellen zu definieren. Eine besondere Rolle spielen dabei Einzellflaschenhälse ("one-cell bottlenecks" / "single-cell bottlenecks").

Einsteins relativity of simultaneity had a deep impact on the pilosophy of time. A first conclusion is that there is no such thing as absolute time. Furthermore according to relativity of simultaneity there is no present in which an open future could come into existence and then pass into a fixed past. According to relativity of simultaneity there is no becoming in a three-dimensional space. There are just changes in a four-dimensional world, often called "block universe". Although many authors refuse (...) this static interpretation of space-time, there is little doubt in the relativity of simultaneity. This is astonishing, because in the present cosmological models the relativity of simultaneity is not valid and the work of Hawking and Ellis has shown that there is good reason to refuse this principle. (shrink)