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A structure is described that can serve as a foundation for a semantics for a modal agentive construction such as sees to it that Q ([ stit: Q]). The primitives are Tree,,Instant, Agent, choice. Eleven simple postulates governing this structure are set forth and motivated. Tree and encode a picture of branching time consisting of moments gathered into maximal chains called histories. Instant imposes a time-like ordering. Agent consists of agents, and choice assigns to each agent and each moment in (...) Tree a set of possible choices, where each possible choice is a set of histories. All of these ingredients are referred to in the semantics suggested for [ stit: Q]. The most complex part of the discussion is the motivation for the definition of what it means for a typically non-terminating chain of moments jointly to witness the truth of [ stit: Q] at a moment.The paper begins with an informal account of the Refref conjecture, which says that the only way to refrain from refraining from seeing to something is to see to it. The paper ends with a consideration of an argument of Prior's that in a certain sense contemplation and action are inconsistent. (shrink)

The main purpose of the paper is to introduce philosophers and philosophical logicians to dynamic logic, a subject which promises to be of interest also to philosophy. A new completeness result involving both after — and during — operators is announced.

This paper pursues the suggestion of St. Anselm that action expressions can be parsed by saying that the agent makes a certain proposition true. Using the model syntax of Pörn and the relatedness logic of Epstein, it is shown how St. Anselm's approach can reveal the logical form of some common action locutions.

The modal logician's notion of possible world and the computer scientist's notion of state of a machine provide a point of commonality which can form the foundation of a logic of action. Extending ordinary modal logic with the calculus of binary relations leads to a very natural logic for describing the behavior of computer programs.

A theory of temporal passage is put forward which is "objective" in the sense that time flow characterizes the universe independently of the existence of conscious beings. The theory differs from Grunbaum's "mind-dependence" theory, and is designed to avoid Grunbaum's criticisms of an earlier theory of Reichenbach's. The representation of temporal becoming is accomplished by the introduction of indeterministic universe-models; each model representing the universe at a time. The models depict the past as a single four-dimensional manifold, and the future (...) as a branched structure of such manifolds. Time flow is relativistic in that it manifests itself in a frame-dependent (but not observer-dependent) way. The indeterministic character of the universe-models is mirrored in a "temporal" theory of truth which rejects the principle of bivalence, and suitable semantics are provided for this theory. Finally, an account of physical law is given which defines it in terms of physical possibility, rather than vice versa. (shrink)

A discussion of work formalising Hohfeld's classic taxonomy of rights relations between two parties.

The aim of this paper is to make a critical assessment of Krister Segerberg''s theory of action. The first part gives a critical presentation of the key concepts in Segerberg''s informal theory of action. These are the ideas that motivate the formal models he develops. In the second part it is argued that if one takes all of Segerberg''s motivating ideas seriously, problems are forthcoming. The main problem is that on this theory the agents seem to be bound to realize (...) all of their intentions, a problem that stems from Segerberg''s attempt to individuate actions in terms of the agent''s intentions. On the ground that this unfortunate result is forthcoming in both of Segerberg''s approaches to the logic of action it is concluded that the conceptual basis of the theory is problematic. (shrink)

This paper offers two related things. First, a theory of singular causal statements attributing causal responsibility for a particular harm to a particular agent based on the conjunction of a positive condition (necessitation) and a negative condition (avoidability) which captures the notions of sufficiency and necessity in intuitive ideas about agent causation better than traditional conditio sine qua non based theories. Second, a theory of representation of causal issues in the law. The conceptual framework is that of Game Trees and (...) Games in Extensive Form. Causal conditions are defined set-theoretically over Game Trees; causal issues and fundamental distinctions (dependent versus independent intervening causes, foreseeability or not of harm etc.) arising in legal cases are accommodated by the device of a probability distribution over the game-tree representation of cases. (shrink)