How do people make deductions? The orthodox view in psychology is that they use formal rules of inference like those of a “natural deduction” system.Deductionargues that their logical competence depends, not on formal rules, but on mental models. They construct models of the situation described by the premises, using their linguistic knowledge and their general knowledge. They try to formulate a conclusion based on these models that maintains semantic information, that expresses it parsimoniously, and that makes explicit something not directly (...) stated by any premise. They then test the validity of the conclusion by searching for alternative models that might refute the conclusion. The theory also resolves long-standing puzzles about reasoning, including how nonmonotonic reasoning occurs in daily life. The book reports experiments on all the main domains of deduction, including inferences based on prepositional connectives such as “if” and “or,” inferences based on relations such as “in the same place as,” inferences based on quantifiers such as “none,” “any,” and “only,” and metalogical inferences based on assertions about the true and the false. Where the two theories make opposite predictions, the results confirm the model theory and run counter to the formal rule theories. Without exception, all of the experiments corroborate the two main predictions of the model theory: inferences requiring only one model are easier than those requiring multiple models, and erroneous conclusions are usually the result of constructing only one of the possible models of the premises. (shrink)

We resolve the two problems that Hardman raises. The first problem arises from a misunderstanding: the crucial distinction is between one-model and multiple-model problems. The second problem illuminates a deeper principle: conclusions depend on the procedures for interpreting models. We describe an algorithm that obviates the problem and empirical work that reveals a new view of syllogistic reasoning.

Van der Henst argues that the theory of mental models lacks a pragmatic component. He fills the gap with the notion that reasoners draw the most relevant conclusions. We agree, but argue that theories need an element of “nondeterminism.” It is often impossible to predict either what will be most relevant or which particular conclusion an individual will draw.

This paper replies to Politzer’s (2007) criticisms of the mental model theory of conditionals. It argues that the theory provides a correct account of negation of conditionals, that it does not provide a truth-functional account of their meaning, though it predicts that certain interpretations of conditionals yield acceptable versions of the ‘paradoxes’ of material implication, and that it postulates three main strategies for estimating the probabilities of conditionals.

This article presents a fundamental advance in the theory of mental models as an explanation of reasoning about facts, possibilities, and probabilities. It postulates that the meanings of compound assertions, such as conditionals (if) and disjunctions (or), unlike those in logic, refer to conjunctions of epistemic possibilities that hold in default of information to the contrary. Various factors such as general knowledge can modulate these interpretations. New information can always override sentential inferences; that is, reasoning in daily life is defeasible (...) (or nonmonotonic). The theory is a dual process one: It distinguishes between intuitive inferences (based on system 1) and deliberative inferences (based on system 2). The article describes a computer implementation of the theory, including its two systems of reasoning, and it shows how the program simulates crucial predictions that evidence corroborates. It concludes with a discussion of how the theory contrasts with those based on logic or on probabilities. (shrink)

Two experiments investigated inferences based on suppositions. In Experiment 1, the subjects decided whether suppositions about individuals' veracity were consistent with their assertions—for example, whether the supposition “Ann is telling the truth and Beth is telling a lie”, is consistent with the premises: “Ann asserts: I am telling the truth and Beth is telling the truth. Beth asserts: Ann is telling the truth”. It showed that these inferences are more difficult than ones based on factual premises: “Ann asserts: I live (...) in Dublin and Beth lives in Dublin”. There was no difference between problems about truthtellers and liars, who always told the truth or always lied, and normals, who sometimes told the truth and sometimes lied. In Experiment 2, the subjects made inferences about factual matters set in three contexts: a truth-inducing context in which friends confided their personality characteristics, a lie-inducing context in which business rivals advertised their products, and a neutral context in which computers printed their program characteristics. Given the supposition that the individuals were lying, it was more difficult to make inferences in a truth-inducing context than in the other two contexts. We discuss the implications of our results for everyday reasoning from suppositions, and for theories of reasoning based on models or inference rules. (shrink)

In amblyopia, abnormal visual experience during development leads to an enduring loss of visual acuity in adulthood. Physiological studies in animal models suggest that intracortical GABAergic inhibition may mediate visual deficits in amblyopia. To better understand the relationship between visual cortical γ-aminobutyric acid (GABA) and perceptual suppression in persons with amblyopia (PWA), we employed magnetic resonance spectroscopy (MRS) to quantify GABA levels in both PWA and normally-sighted persons (NSP). In the same individuals, we obtained psychophysical measures of perceptual suppression for (...) a variety of ocular configurations. In PWA, we found a robust negative correlation between the depth of amblyopia (the difference in visual acuity between the amblyopic and non-amblyopic eyes) and GABA concentration that was specific to visual cortex and was not observed in a sensorimotor cortical control region. Moreover, lower levels of visual cortical GABA were associated with weaker perceptual suppression of the fellow eye by the amblyopic eye and stronger suppression of the amblyopic eye by the fellow eye. Taken together, our findings provide evidence that intracortical GABAergic inhibition is an important component of the pathology of human amblyopia and suggest possible therapeutic interventions to restore vision in the amblyopic eye through enhancement of visual cortical GABAergic signaling in PWA. (shrink)

The Scottish Mental Health Arts and Film Festival has seen hundreds of arts, public and community groups coproduce over 300 events to over 25,000 audience members. Integral to this arts-based approach, in contrast to social marketing or public education models, is the notion that mental health is an essentially contested concept whereby meanings are negotiated and debate encouraged. With emerging evidence that the festival is an ef ective way of engaging people intellectually and emotionally, we explore ethical issues, challenges and (...) paradoxes that have emerged as the festival has developed. Consideration is given to issues of power, purpose, opportunity costs, reach, impact, programming risks, and participation from those with experience of mental ill-health. Throughout, we explore practical implications for funding, managing, programming, marketing and evaluation of this and similar endeavours. (shrink)

Two recently published oral histories highlight the long-term trend concerning the mainstreaming of Objectivism, the political and economic ideas of the libertarian conservative writer and ideologue, Ayn Rand. Scott McConnell’s sympathetic interview collection focuses on supporters and acquaintances from Rand’s active period in the 1960s and 1970s. These supporters and acquaintances include former Australian Prime Minister, Malcolm Fraser, who provides McConnell with his considered views concerning Rand. Gary Weiss’s critical interview collection focusses on her more recent supporters, with one displeased (...) and insightful interviewee to be found in both collections. Weiss’s collection reveals the role played by Objectivists in galvanizing the focus of the populist Tea Party movement. Both oral histories reveal the role played by the media and popular culture in mainstreaming Rand’s views. The review ends by comparing Randolph Stow’s socially responsive individualism as described in his novel 'Tourmaline' with Rand’s transactional individualism as described in 'Atlas Shrugged.'. (shrink)

Jonardon Ganeri, Paul Noordhof, and Murali Ramachandran (1996) have proposed a new counterfactual analysis of causation. We argue that this – the PCA-analysis – is incorrect. In section 1, we explain David Lewis’s first counterfactual analysis of causation, and a problem that led him to propose a second. In section 2 we explain the PCA-analysis, advertised as an improvement on Lewis’s later account. We then give counterexamples to the necessity (section 3) and sufficiency (section 4) of the PCA-analysis.

For many years Sir Roger Scruton’s incendiary pen, his own fine-point flamethrower, provoked outrage in the fields of journalism, literature, and in popular, as well as academic studies. As a philo...

As a preliminary step to beginning to assess the usefulness of clinical vignettes to measure ethical sensitivity in undergraduate medical students, five clinical vignettes with seven to nine ethical issues each were created. The ethical issues in the vignettes were discussed and outlined by an expert panel. One randomly selected vignette was presented to first, second and third year students at the University of Toronto as part of another examination. The students were asked to list the issues presented by the (...) patient problem. Responses from 281 students were obtained. These students identified an average of 2.72 ethical issues per vignette. Each response was classified under the domains of autonomy, beneficence and justice. Comparisons were made between classes and between vignettes. There was considerable variation between classes and the responses to different vignettes seem to indicate that different vignettes measure the various domains in different ways. It does appear that the use of vignettes is one way to measure aspects of ethical sensitivity in medical students but more study is required to clarify exactly what is being measured. (shrink)

The basis of science is the hypothetico-deductive method and the recording of experiments in sufficient detail to enable reproducibility. We report the development of Robot Scientist "Adam," which advances the automation of both. Adam has autonomously generated functional genomics hypotheses about the yeast Saccharomyces cerevisiae and experimentally tested these hypotheses by using laboratory automation. We have confirmed Adam's conclusions through manual experiments. To describe Adam's research, we have developed an ontology and logical language. The resulting formalization involves over 10,000 different (...) research units in a nested treelike structure, 10 levels deep, that relates the 6.6 million biomass measurements to their logical description. This formalization describes how a machine contributed to scientific knowledge. (shrink)

In lieu of an abstract, here is a brief excerpt of the content: Reviewed by:Art and Politics in Roger Scruton’s Conservative Philosophy by Ferenc HÖRCHERD. N. ByrneHÖRCHER, Ferenc. Art and Politics in Roger Scruton’s Conservative Philosophy. Palgrave Macmillan, 2022. vii + 404 pp. Cloth, $129.99The intellectual legacy of Sir Roger Scruton defies the conventional wisdom that conservatism is a mood or sensibility rather than a systematic body of ideas. Then, as Hörcher indicates, Scruton was never a particularly conventional thinker. Against (...) the current that equated intellectualism with political critique, Scruton espoused traditionalism, community ahead of individualism, and order against pluralism. Against the current as well, he took his reflections to the court of public opinion rather than to the halls of academe. (shrink)

Book review of Drew Maciag's account of the changing role of Edmund Burke's political thought in the U.S.

The rising tide of conservatism, a flow that has resulted in the re-modelling, indeed the reduction, of the public sphere and the re-organisation of civil society in all of the economically develop...

In lieu of an abstract, here is a brief excerpt of the content:Comments on “Moral Complicity in Induced Pluripotent Stem Cell Research”W. Malcolm Byrnes, Ph.D. and Edward J. FurtonIn his article titled “Moral Complicity in Induced Pluripotent Stem Cell Research,” Mark T. Brown (2009) unfortunately mischaracterizes my ethical analysis of the use of induced pluripotent stem (iPS) cells for replacement therapies, or treatments (Byrnes 2008). In my paper, which Brown cites, I argue that, just as it is ethically acceptable for (...) parents to allow their children and themselves to be immunized using vaccines produced by cell lines derived from human fetuses aborted in the past, it is also acceptable for persons in the future to benefit from treatments that use iPS cells validated using human embryonic stem (ES) cell lines [End Page 202] derived in the past. The assumption I make is that iPS cells would have to be shown to be functionally equivalent to human ES cells—i.e., validated—before they could be used for cell replacement treatments. (If it turns out that this assumption is incorrect, and primate or even mouse ES cells can be used for the validation, then all residual ethical problems will disappear and there will be no ethical problems whatsoever associated with iPS cells.) I wrote:... [I]n both cases, the origin of the treatment is in a one-time event: either the one-time use of aborted fetuses to obtain cell lines (e.g., MRC-5 and WI- 38) to grow weakened virus strains for vaccine production, or the one-time destruction of human embryos to validate iPS cells, which then effectively replace embryonic stem cells. In the latter case, if no additional embryonic stem cell lines are derived, then derivation of the existing lines could be considered a “one-time” event in the past, albeit an event that extended over a several-year period(Byrnes 2008, p. 287, emphasis added).Note the phrase “if no additional embryonic stem cell lines are derived.” The derivation of ES cell lines inherently involves destruction of embryos; indeed, that is why many people, including me, are opposed to human ES cell research. In my article, I am arguing that, if no additional ES cell lines are derived, then no additional human embryos will be destroyed, and the destruction of human embryos will lie in the past. In this case, embryo destruction could be considered a past event, just as the abortion of a human fetus from which vaccine-producing cell lines were derived is a past, albeit tragic, event.In the process of building his argument that proponents of iPS cell research are morally complicit in embryo destruction, Brown (2009, p. 15) casts me as being in favor of the “derivation of new embryonic stem [cell lines].” This is the exact opposite of my position. In fact, I am opposed to further destruction of human embryos. I believe that the hundreds of ES cell lines already in existence are more than sufficient to validate iPS cells and so no additional lines need to be derived. This means that no additional human embryos will need to be destroyed.Apparently based on the misperception that I support future destruction of human embryos, Brown concludes that “Byrnes’s endorsement of ongoing iPSC validation studies would seem to implicate him and those who follow his lead in formal and material complicity in what they perceive as moral evil” (p. 16). He writes that “explicit formal complicity would attach because he [Byrnes] knowingly and intentionally recommends that embryos be killed in order to facilitate a transition to a future in which no more embryos need be destroyed” (p. 16). Additionally, my “followers” and I would be guilty of “proximate material complicity” as well as “remote material complicity” (p. 16). Unfortunately, this broad condemnation is based on a misconception of my actual position.An additional problem involves Brown’s use of a quotation he attributes to me: [End Page 203]Once embryonic stem cells are used to successfully validate iPS cells, they will no longer be needed and their association with iPS cells will lie in the past. Is there not an element of sadness and resignation in accepting something (iPS cells) associated with an unjust act (destruction of an... (shrink)

When people think about how a situation might have turned out differently, they tend to imagine counterfactual alternatives to their actions. We report the results of three experiments which show that people imagine alternatives to actions differently when they know about a reason for the action. The first experiment ( n = 36) compared reason - action sequences to cause - effect sequences. It showed that people do not imagine alternatives to reasons in the way they imagine alternatives to causes: (...) they imagine an alternative to an action more than an effect, and to a cause more than a reason. The second experiment ( n = 214) and the third experiment ( n = 190) both show that different sorts of reasons have different sorts of effects on how people imagine alternatives to actions. People imagine an alternative to an action (the protagonist went to a ball) less often when they know the reason for the action was an obligation (he had to participate in fundraising) compared to when they know about a weaker reason (he wanted to meet a famous violinist) or no reason. The second experiment shows the effect for a social obligation and the third experiment replicates and extends it to a health obligation. We interpret the results in terms of the possibilities that people keep in mind about actions and their reasons. (shrink)

RÉSUMÉBeaucoup ont soutenu qu'il n'y a pas de place pour des expériences scientifiques dans les sciences naturelles d'Aristote : les expériences interviennent dans la nature, mais Aristote soutient que nous devons simplement observer la nature; si nous intervenions, le résultat serait quelque chose d'artificiel ou contraire à la nature. Contre cela, je soutiens qu'Aristote a non seulement effectué des expériences scientifiques, mais a également maintenu qu'il y a beaucoup de connaissances sur la nature qui peuvent être découvertes expérimentalement.

The diversity of topics discussed in this book reflects the breadth of Judith Jarvis Thomson's philosophical work. Throughout her long career at MIT, Thomson's straightforward approach and emphasis on problem-solving have shaped philosophy in significant ways. Some of the book's contributions discuss specific moral and political issues such as abortion, self-defense, the rights and obligations of prospective fathers, and political campaign finance. Other contributions concern the foundations of moral theory, focusing on hedonism, virtue ethics, the nature of nonconsequentialism, and the (...) objectivity of moral claims. Finally, contributions in metaphysics and epistemology discuss the existence of sets, the structures reflected in conditional statements, and the commitments of testimony. Contributors: Jonathan Bennett, Richard L. Cartwright, Joshua Cohen, N. Ann Davis, Catherine Z. Elgin, Gilbert Harman, Barbara Herman, Frances Myrna Kamm, Claudia Mills, T.M. Scanlon, Ernest Sosa. (shrink)

Il s'agit ici de la dimension existentielle de la theorie morale de S. Thomas d'Aquin. Pour lui, le domaine de l'incertain est generalement coextensif a celui de la contingence, de ce qui peut etre autre qu'il n'est. En general, S. Thomas envisage la contingence de la meme maniere qu'Aristote, mais dans une perspective totalement differente. Theologien, il s'interesse au monde physique surtout comme manifestation de la sagesse divine vers laquelle il desire monter. Il ne dedaigne pas pour autant les outils (...) de la science humaine, mais il les voit au service d'un dessein sacre. C'est dans cette perspective qu'il s'autorise a "calculer" le contingent. Car, d'apres lui, quel que soit son ideal, l'homme en quete de Dieu doit se frayer un chemin dans un univers qui, a ses yeux du moins, est expose a l'intervention du hasard. (shrink)

We propose that the pragmatic factors that mediate everyday deduction, such as alternative and disabling conditions (e.g. Cummins et al., 1991) and additional requirements (Byrne, 1989) exert their effects on specific inferences because of their perceived relevance to more general principles, which we term SuperPs. Support for this proposal was found first in two causal inference experiments, in which it was shown that specific inferences were mediated by factors that are relevant to a more general principle, while the same (...) inferences were unaffected by factors not relevant to the general principle. These results were extended to deontic inferences in two further experiments. Taken together, these findings show that unstated superordinate principles play a significant role in certain types of reasoning. Questions raised by the findings for the main theoretical approaches are discussed. (shrink)

Byrne (2005) assumes that counterfactual thinking requires a comparison of facts with an imagined alternative. In our view, however, this assumption is unnecessarily restrictive. We argue that individuals do not necessarily engage in counterfactual simulations exclusively to evaluate factual reality. Instead, comparative evaluation is often suspended in favor of experiencing the counterfactual simulation as if it were real.