We show that the implicational fragment of intuitionism is the weakest logic with a non-trivial probabilistic semantics which satisfies the thesis that the probabilities of conditionals are conditional probabilities. We also show that several logics between intuitionism and classical logic also admit non-trivial probability functions which satisfy that thesis. On the other hand, we also prove that very weak assumptions concerning negation added to the core probability conditions with the restriction that probabilities of conditionals are conditional probabilities are sufficient to (...) trivialize the semantics. (shrink)

Conclusions reached using common sense reasoning from a set of premises are often subsequently revised when additional premises are added. Because we do not always accept previous conclusions in light of subsequent information, common sense reasoning is said to be nonmonotonic. But in the standard formal systems usually studied by logicians, if a conclusion follows from a set of premises, that same conclusion still follows no matter how the premise set is augmented; that is, the consequence relations of standard logics (...) are monotonic. Much recent research in AI has been devoted to the attempt to develop nonmonotonic logics. After some motivational material, we give four formal proofs that there can be no nonmonotonic consequence relation that is characterized by universal constraints on rational belief structures. In other words, a nonmonotonic consequence relation that corresponds to universal principles of rational belief is impossible. We show that the nonmonotonicity of common sense reasoning is a function of the way we use logic, not a function of the logic we use. We give several examples of how nonmonotonic reasoning systems may be based on monotonic logics. (shrink)

Counterfactual imaginings are known to have far reaching implications. In the present experiment, we ask if imagining events from one's past can affect memory for childhood events. We draw on the social psychology literature showing that imagining a future event increases the subjective likelihood that the event will occur. The concepts of cognitive availability and the source monitoring framework provide reasons to expect that imagination may inflate confidence that a childhood event occurred. However, people routinely produce myriad counterfactual imaginings (i.e., (...) daydreams and fantasies) but usually do not confuse them with past experiences. To determine the effects of imagining a childhood event, we pretested subjects on how confident they were that a number of childhood events had happened, asked them to imagine some of those events, and then gathered new confidence measures. For each of the target items, imagination inflated confidence that the event had occurred in childhood. We discuss implications for situations in which imagination is used as an aid in searching for presumably lost memories. (shrink)

In [2] Hempel and Oppenheim give a definition of “explanation” for a certain formal language. In [1] Eberle, Kaplan, and Montague prove five theorems demonstrating that the Hempel and Oppenheim definition is not restrictive enough. In [3] Kim proposes two further conditions to supplement the Hempel and Oppenheim definition in order to avoid the objections posed in [1]. In this paper it is shown that the definition of Hempel and Oppenheim supplemented by Kim's conditions is open to a trivialization very (...) analogous to that given in [1]. (shrink)

The usual semantics for the modal systems T, S4, and S5 assumes that the set of possible worlds contains at least one member. Recently versions of these modal systems have been developed in which this assumption is dropped. The systems discussed here are obtained by slightly weakening the liberated versions of T and S4. The semantics does not assume the existence of possible worlds, and the accessibility relation between worlds is only required to be quasi-reflexive instead of reflexive. Completeness and (...) independence results are established. (shrink)

The intuitive notion behind the usual semantics of most systems of modal logic is that of ?possible worlds?. Loosely speaking, an expression is necessary if and only if it holds in all possible worlds; it is possible if and only if it holds in some possible world. Of course, contradictory expressions turn out to hold in no possible worlds, and logically true expressions turn out to hold in every possible world. A method is presented for transforming standard modal systems into (...) systems of modal logic for impossible worlds. To each possible world there corresponds an impossible world such that an expression holds in the impossible world if and only if it does not hold in the possible world. One can then talk about such worlds quite consistently, and there seems to be no logical reason for excluding them from consideration. (shrink)

Almost every formal model of explanation thus far proposed has been demonstrated to be faulty. In this paper, a new model, proposed by Raimo Tuomela, is also demonstrated to be faulty. In particular, one condition of the model is shown to be too restrictive, and another condition of the model is shown to be too permissive.

Modern cells present no signs of a putative prebiotic RNA world. However, RNA coding is not a sine qua non for the accumulation of catalytic polypeptides. Thus, cellular proteins spontaneously fold into active structures that are resistant to proteolysis. The law of mass action suggests that binding domains are stabilized by specific interactions with their substrates. Random polypeptide synthesis in a prebiotic world has the potential to initially produce only a very small fraction of polypeptides that can fold spontaneously into (...) catalytic domains. However, that fraction can be enriched by proteolytic activities that destroy the unfolded polypeptides and regenerate amino acids that can be recycled into polypeptides. In this open system scenario the stable domains that accumulate and the chemical environment in which they are accumulated are linked through self coding of polypeptide structure. Such open polypeptide systems may have been the precursors to the cellular ribonucleoprotein (RNP) world that evolved subsequently. (shrink)

Collingwood's attitude toward literary sources is related to the method of selective excavation. But as an excavator, Collingwood came in for some criticism from his fellow archaeologists. Collingwood's treatment of four historical problems is considered: why Caesar invaded Britain, why Augustus did not, how the Claudian conquest proceeded, and why Hadrian built his wall and vallum. Collingwood concluded that Caesar intended to conquer, Augustus did not, and that the vallum served a civil rather than military purpose. In trying to identify (...) past thought Collingwood approaches literary sources and archaeological remains with particular questions in mind. Questions and answers being correlative, this often amounts to having made up his mind in advance. When he comes to the evidence itself, he sees what he expects to see ; occasionally what he sees is not in fact there. Where Collingwood creates a history, Peter Salway sometimes seems to be summarizing a subject. With Collingwood, however, we more than participate in processes of thought, we actually see the connections. Collingwood makes the real rational, and no historian of Roman Britain has done that better. (shrink)

The twelve contributors to Looking for Los Angeles focus on dramatic shifts in the urban landscape, important moments in the city's architectural history, and the role of the image in this mecca of image makers.

Dawkins in his The Selfish Gene(1) quite aptly applies the term “selfish” to parasitic repetitive DNA sequences endemic to eukaryotic genomes, especially vertebrates. Doolittle and Sapienza(2) as well as Orgel and Crick(3) enlivened this notion of selfish DNA with the identification of such repetitive sequences as remnants of mobile elements such as transposons. In addition, Orgel and Crick(3) associated parasitic DNA with a potential to outgrow their host genomes by propagating both vertically via conventional genome replication as well as infectiously (...) by horizontal gene transfer (HGT) to other genomes. Still later, Doolittle(4) speculated that unchecked HGT between unrelated genomes so complicates phylogeny that the conventional representation of a tree of life would have to be replaced by a thicket or a web of life.(4) In contrast, considerable data now show that reconstructions based on whole genome sequences are consistent with the conventional “tree of life”.(5–10) Here, we identify natural barriers that protect modern genome populations from the inroads of rampant HGT. BioEssays 27:741–747, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

The business enterprise is a major instrument in the creation of a just society. However the tension between profit and ethicality requires sound decision making and business ethics instruction is central to creative alternatives to business leaders. Therefore, instruction is aided with a model for framing one’s thoughts about ethics and while several earlier business ethics models exist, they tend to be closed and at times parochial. This paper draws on insights from other academic disciplines to offer a broader yet (...) flexible framework for professors, students, scholars, and decision makers. At the center of the model is the four stage framework of Rest et al. as impacted by four sets of variables—individual, organizational, environmental, and issue. These are rooted in the work of Dunlop’s Industrial Relations Theory and Jones’ Moral Intensity. A literature review of important variables is presented and the paper concludes with several take aways for instruction and policy suggestions. (shrink)

Erasmus’s Adages were among his most influential works in his own time, particularly later editions, which included both Greek and Latin. In the adages included in volumes 35 and 36, Erasmus criticizes secular and ecclesiastical life, commenting on topics such as war, reform of the church and spiritual life, and the corrupting effects of the relentless pursuit of wealth and power. Erasmus aims his narrative and commentary in Paraphrase on the Gospel of Matthew (volume 45) at a general educated audience (...) (rather than professional theologians). Together, these volumes provide readable and accurate edition of Erasmus’s work and helpful special indexes. (shrink)

(2012). The Making of the Humanities, vol. 1: Early Modern Europe. Intellectual History Review: Vol. 22, No. 2, pp. 293-296. doi: 10.1080/17496977.2012.694178.

Two studies explored individual differences in appraisal of minor, potentially stressful events. Previous research on appraisal has focused on one or two appraisal dimensions within specific situations rather than on the full range of appraisals or on the stability of appraisal across situations. Goals of the present studies were: (1) to explore stability of individual differences in appraisal across situations; (2) to identify individual differences in general appraisal styles; and (3) to examine how appraisal styles are related to personality constructs. (...) Appraisal was moderately stable across situations and individual differences in appraisal style were related to relevant personality constructs. Primary threat appraisals and secondary appraisals of blame and manageability emerged as particularly important in distinguishing the appraisal styles. Implications of the results for the development of psychopathology are considered. (shrink)