Online research in philosophy

In this article, ambiguity attitude is measured through the maximum price a decision maker is willing to pay to know the probability of an event. Two problems are examined in which the decision maker faces an act: in one case, buying information implies playing a lottery, while, in the other case, buying information gives also the option to avoid playing the lottery. In both decision settings, relying on the Choquet expected utility model, we study how the decision maker’s risk and ambiguity attitudes affect the reservation price for ambiguity resolution. These effects are analyzed for different levels of ambiguity of the act. Operating instructions for the elicitation of the reservation price for ambiguity resolution in an experimental setting are provided at the end of the article.

We generalize the concept of Nash equilibrium in mixed strategies for strategic form games to allow for ambiguity in the players' expectations. In contrast to other contributions, we model ambiguity by means of so-called lower probability measures or belief functions, which makes it possible to distinguish between a player's assessment of ambiguity and his attitude towards ambiguity. We also generalize the concept of trembling hand perfect equilibrium. Finally, we demonstrate that for certain attitudes towards ambiguity it is possible to explain cooperation in the one-shot Prisoner's Dilemma in a way that is in accordance with some recent experimental findings.

Stoic work on ambiguity represents one of the most innovative, sophisticated, and rigorous contributions to philosophy and the study of language in western antiquity. This book is both the first comprehensive survey of the often difficult and scattered sources, and the first attempt to locate Stoic material in the rich array of contexts, ancient and modern, which alone can guarantee full appreciation of its subtlety, scope and complexity. The comparisons and contrasts which this book constructs will intrigue not just classical scholars, and philosophers, but also logicians, theoretical linguists, communication theorists and historians of grammar and of literary theory. The Stoics on Ambiguity is designed to be intelligible to readers with no Greek or Latin.

Gambles which induce the decision-maker to experience ambiguity about the relative likelihood of events often give rise to ambiguity-seeking and ambiguity-avoidance, which imply violation of additivity and Savage's axioms. The inability of the subjective Bayesian theory to account for these empirical regularities has determined a dichotomy between normative and descriptive views of subjective probability. This paper proposes a framework within which the two perspectives can be reconciled. First, a formal definition of ambiguity is given over a continuum ranging from ignorance to risk, and including ambiguous contexts as subsets. Second, it is shown that the systems of inductive logic account for the effects of ambiguity. Then, Carnap's X-system is applied as a psychological model and compared to Einhorn and Hogarth's non-normative psychological model. Finally, the implications of this research to the modeling of subjective probability judgements are discussed.

The Ellsberg Paradox documented the aversion to ambiguity in the probability of winning a prize. Using an original sample of 266 business owners and managers facing risks from climate change, this paper documents the presence of departures from rationality in both directions. Both ambiguity-seeking behavior and ambiguity-averse behavior are evident. People exhibit ‘fear’ effects of ambiguity for small probabilities of suffering a loss and ‘hope’ effects for large probabilities. Estimates of the crossover point from ambiguity aversion (fear) to ambiguity seeking (hope) place this value between 0.3 and 0.7 for the risk per decade lotteries considered, with empirical estimates indicating a crossover mean risk of about 0.5. Attitudes toward the degree of ambiguity also reverse at the crossover point.

Two principal sources of imprecision in legal drafting (vagueness and ambiguity) are identified and illustrated. Virtually all of the ambiguity imprecision encountered in legal discourse is ambiguity in the language used to express logical structure, and virtually all of the imprecision resulting is inadvertent. On the other hand, the imprecision encountered in legal writing that results from vagueness is frequently, if not most often, included there deliberately; the drafter has considered it and decided that the vague language best accomplishes the purpose at hand. This paper focuses on the use of some defined terminology for minimizing inadvertent ambiguity in the logical structure of legal discourse, where desired by the drafter. The current set of signaled structural definitions that are included in the A-Hohfeld language are first set forth and their use is illustrated in an extensive example from the treaty establishing the European Economic Community. The use of definitions in legal writing is widespread, butaddressed almost exclusively to controlling the vagueness of substantive legal terms; they are seldom used for structural purposes. Furthermore, their use in American legislative drafting is unsignaled. Here, attention is devoted to the relatively-neglected domain in legal discourse of imprecisely expressed logical structure, and the remedy offered, where desired by the drafter, is a set of signaled structuraldefinitions for use in controlling such imprecision.

We generalize Specker's theorem on typical ambiguity, that NF and TST + Ambiguity have the same stratified consequences, to the subschemes Amb(Γ) of ambiguity restricted to classes of sentences Γ with certain natural closure conditions.

Donnellan (1966) makes a convincing case for two distinct uses ofdefinite descriptions. But does the difference between the usesreflects an ambiguity in the semantics of descriptions? This paperapplies a linguistic test for ambiguity to argue that the differencebetween the uses is not semantically significant.