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)

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)

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)

These essays by some of the most prominent figures in linguistics, artificial intelligence, and psychology explore the problems involved in creating a general cognitive science that will treat language, thought, and behavior in an integrated fashion. They address the fundamental questions of the relations between linguistic structures and cognitive processes, between cognitive processes and language behavior, and between language behavior and linguistic structure. Contents: Introduction, Thomas G. Bever (Columbia University), John M. Carroll and Lance A. Miller (IBM Thomas J. Watson (...) Research Center). "Philosophy and "Linguistics: An Outline of Platonist Grammar, Jerrold J. Katz (CUNY). Sense and Reference in a Psychologically Based Semantics, Ray Jackendoff (Brandeis University). Some Thoughts on the Boundaries and Components of Linguistics, Charles J. Fillmore (University of California, Berkeley). Psychology: Approaches to the Study of the Psychology of Language, Walter Kintsch (University of Colorado). Toward An Abstract Performance Grammar, Charles E. Osgood (University of Illinois). Upgrading a Mind, David Premack (University of Pennsylvania). Computational "Models: "Memory, Meaning, and Syntax, Roger Schank (Yale University) and Lawrence Birnbaum (Yale University). Some Inadequate Theories of Human Language Processing, Mitchell P. Marcus (AT&T Bell Laboratories). (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)

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)

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.

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)

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)

Most of us came into ecology with memories of special personal places. A cliff top that Claude Monet might have painted. Allen as a youth spent his holidays on the Dorset Coast near Swanage; he can still smell the sea breeze of his childhood. Curtin grow up on a farm in southwestern Wisconsin, the dew of the grass and the bright green on a June morning remains vivid. The catching of reptiles and insects for him awakened a curiosity about the (...) natural world that has remained to this day. But once into the field there came the scholarship. With ever tighter grant monies, the pressure to publish takes so much of the fun out of it. A climate of unbridled careerism prevails and shows itself in the incremental state of the literature: little things to list on this year's activities report. There are now even predatory journals that cynically do not seriously review submissions, and only collect page charges. As journal editors have a desperate time getting reviews done by mature scholars, instead of a hand off to their overworked graduate students. So what is to be done - how can we bring the joy and importance of discovery back into it all? After all ecology is done by human beings. Mostly it is a personal mission, for what great ecologists write is frequently personal and life changing. So an undercurrent of this book is to remind and reveal the original purpose of science. Not professional advancement, but the genuine search for novel ideas and the imperative to share hard won insights and personal passions. (shrink)

Abstract The increasing prevalence of armed drones in the conduct of military operations has generated robust debate. Among legal scholars, the crux of the dispute generally pits those who herald the new technology's unparalleled precision against those who view such newfound capabilities as an inducement to employ excessive force. Largely overlooked in the discussion over how drone strikes can be accomplished lawfully is a more fundamental question: Can a model of warfare that eschews any risk of harm to one party (...) be squared with the ethical framework that informs the law of war? This matter has less to do with the technology per se than with a policy orientation that utilizes such technology as a strategy in itself, as opposed to one military tool in a larger arsenal. A corollary to the incongruity of riskless warfare is to query whether the ensuing breakdown of ethical and legal norms unwittingly encourages the very instability that the law of war attempts to control, thereby endangering the civilian populations of all parties to the conflict. While other authors have previously addressed the challenges posed by asymmetry to the law of armed conflict in different formats, this article explores these issues through a hypothetical scenario and seeks to elucidate some of the potential ramifications of the pursuit of physical impunity in war. (shrink)

This essay posits that Peirce puts the Normative Sciences implicitly to work at three junctures of his Neglected Argument for the Reality of God (NARG): (1) in the distinguishing of musement from play; (2) in the generation of the Humble Argument via musement; and (3) in the portrayal of the Humble Argument as the first stage of an inquiry into its confirmability. Then, focus shifts to Peirce’s notions of the initiating “play” and the “plausibility” of the God-hypothesis, as a means (...) both to analyze and underscore the foundational role of esthetics in the Normative Sciences. After a discussion of the theological content of the argument, the essay concludes that Peirce did indeed employ the Normative Sciences as postulated, but that his truncation of NARG at the abductive stage renders the overall argument inconclusive, amounting more to a report of a religio-esthetic experience. (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)