Defeasibility and Gettierization: A Reminder

For some of us, the defeasibility theory of knowledge remains the most plausible approach to the Gettier Problem. Epistemological fashion and faded memories notwithstanding, persuasive objections to the theory are very hard to find. The most impressive of those objections to the theory that have hitherto gone unanswered are examined and rejected here. These are objections put forward by Richard Feldman, Richard Foley, and John Turri. While these are all interesting, the objection recently put forward by Turri is, we think, by far, the most serious threat to the theory that we have seen in a long time. A successful reply to it requires a surprising amount of care, as it turns out. If tenable, Turri's objection deals a devastating blow to the theory developed by Roderick Chisholm, Keith Lehrer, Peter Klein, Marshall Swain, Risto Hilpinen, John Pollock, and Paul Moser, among others. Under scrutiny, however, the threat proves illusory. It results from inattention to a crucial, but relatively subtle, aspect of the theory. Interestingly, there is only one source in the defeasibilist literature for a precise account of this crucial feature of the theory: one of the most neglected passages in Peter Klein's work on the issue. That crucial feature is put under the spotlight here. Our response to three major objections to the defeasibility theory requires a brief introduction to the theory as an anti-Gettier weapon, an introduction aimed at countering the numbing simplicity that characterizes most introductions to the topic. Following this brief introduction, those three objections are tackled. We conclude, on that basis, that anybody who fails to notice how resilient the defeasibility theory has proven to be for the last fifty years has a seriously deficient understanding of the current state of play in the debate over the Gettier Problem.     

Back to Black

This is a brief sequel to Max Black's classic dialogue on the Identity of Indiscernibles. Interlocutor A defends the bundle theory by endorsing the (by now popular) view according to which Black's world does not contain two indiscernible spheres but rather a single, bi‐located sphere. His opponent, B, objects that A cannot distinguish such a world from a world with a single, uniquely located sphere, hence that the view in question adds nothing to A's original response to Black's challenge. A is simply denying that there can be worlds with two or more indiscernible entities.     

Theoretical Speculations on the Evolutionary Origins of Hemispheric Specialization

ABSTRACT— Hemispheric specialization has long been considered a uniquely human trait associated with the evolution of language and handedness. Recent studies in a host of vertebrate species have reported evidence of population-level behavioral and brain asymmetries, challenging the claims for the uniqueness of hemispheric specialization to the human species. Here we summarize the findings in nonhuman species and discuss the adaptive significance and potential costs of lateralization of function.     

Foraging and associative learning of visual signals in a parasitic wasp

To cope with environmental variability, animals should gather and use information to reduce uncertainty. In insect parasitoids, associative learning has been widely documented in the context of host foraging. However, despite its potential adaptive value, the insect food searching strategy and cues used to search are poorly understood. In this study, we examined the ability of hymenopteran Venturia canescens females to associate food to a visual cue. To broaden the scope of our results, experiments were performed with both arrhenotokous (sexual) and thelytokous (asexual) individuals. The wasps showed innate attraction for yellow and orange stimuli when presented versus blue stimuli. When trained to associate a food reward with one of the attractive colours (orange), they significantly moved from a distance towards the colour previously associated with food. The choice of the innately preferred colour (yellow) was not modified by associative learning. In the context of food foraging, this study is the first to show associative learning using visual stimuli in a parasitoid and active choice of this colour. This ability gives new insights concerning potential food sources for V. canescens in the field, since flowers are sugar sources, which emit colour signals.     

Weight Bias Internalization Scale Discriminates Obese and Overweight Patients with Different Severity Levels of Depression: the Italian Version of the WBIS

We have investigated the psychometric properties of the Italian version of the weight bias internalization scale (WBIS) in overweight and obese patients who were attending weight loss programs. Participants were 386 overweight and obese patients admitted in two medical centers specializing in the treatment of obesity. All the patients were administered the WBIS, and measures of binge eating, depression, self-esteem, and body dissatisfaction. Confirmatory factor analysis failed to confirm the fit of the original 11-item unidimensional model. Item analysis and exploratory factor analysis indicated that 9 items included in the original measure (the items 1 and 9 were excluded because low item-total correlations) formed a reliable unidimensional measure of internalized weight bias (WBIS-9). The WBIS-9 was significantly correlated with convergent measures and was able to categorize individuals with different severity levels of depression (sensitivity of 0.72 and specificity of 0.70). The WBIS-9 may be useful in clinical practice to discriminate patients with more severe psychopathology, comorbid disordered eating patterns, and risk for poor outcomes.     

Close to me: multisensory space representations for action and pre-reflexive consciousness of oneself-in-the-world

Philosophical considerations as well as several recent studies from neurophysiology, neuropsychology, and psychophysics converged in showing that the peripersonal space (i.e. closely surrounding the body-parts) is structured in a body-centred manner and represented through integrated sensory inputs. Multisensory representations may deserve the function of coding peripersonal space for avoiding or interacting with objects. Neuropsychological evidence is reviewed for dynamic interactions between space representations and action execution, as revealed by the behavioural effects that the use of a tool, as a physical extension of the reachable space, produces on visual-tactile extinction. In particular, tool-use transiently modifies action space representation in a functionally effective way. The possibility is discussed that the investigation of multisensory space representations for action provides an empirical way to consider in its specificity pre-reflexive self-consciousness by considering the intertwining of self-relatedness and object-directness of spatial experience shaped by multisensory and sensorimotor integrations.     

Cooperative responding in rats: II. Performance on fixed-ratio schedules of mutual reinforcement

Coordinated responses of 5 dyads of rats were investigated under fixed-ratio (FR) schedules of mutual water reinforcement. Coordinated responding was defined as 2 consecutive lever-presses, 1 from each of 2 rats, occurring <.5 s apart. In the FR schedules, each coordinated episode was defined as 1 response in the FR sequence. The size of FR schedules was parametrically manipulated assuming the values of FR 1, 6, 12, 18, 24, 30, 50, and 9, in this order. Each FR remained in effect until responding reached stability. Under all conditions, pairs of rats received access to water simultaneously (mutual reinforcement). Rates and proportions of coordinated responding showed a bitonic inverted U-shaped function of ratio size. Postreinforcement pauses increased systematically as the interreinforcement interval increased. Local rates and proportions increased as a function of response location within ratios. Results of a control condition with relaxed temporal constraints for mutual reinforcement showed decreases in rates and proportion of coordinated responses, suggesting that the coordinated responses were controlled by the mutual reinforcement contingencies. The present experiment showed that coordinated responding is quantitatively affected by 3 properties of FR schedules: response requirement, reinforcement rates, and proximity to reinforcement.     

Enhancing Nature Conservation and Health: Changing the Focus to Active Pro-environmental Behaviours

Most research about the promotion of pro-environmental behaviours has focused on actions conducted at home (e.g. energy saving). While acknowledging their relevance, the effect of such behaviours on the mitigation of two of the most relevant global environmental problems (climate change and biodiversity loss) is relatively small. We present a literature review with two main objectives. First is to introduce the concept of active pro-environmental behaviours. These are a combination of outdoor physical activities and pro-environmental behaviours. The latter involve behaviours that have a minimum impact on the environment, or even have positive consequences for the environment. Active commuting and tree planting are examples of active pro-environmental behaviours. The second objective is to discuss the relevance of active pro-environmental behaviours for people’s health and sustainability and, thereby, to encourage more research and efforts towards the promotion of these behaviours. We conclude by suggesting how stakeholders can promote active pro-environmental behaviours.