The thresholds of human observers detecting line targets improve significantly when the targets are presented in a spatial context of collinear inducing stimuli. This phenomenon is referred to as spatial facilitation, and may reflect the output of long-range interactions between cortical feature detectors. Spatial facilitation has thus far been observed with luminance-defined, achromatic stimuli on achromatic backgrounds. This study compares spatial facilitation with line targets and collinear, edge-like inducers defined by luminance contrast to spatial facilitation with targets and (...) inducers defined by color contrast. The results of a first experiment show that achromatic inducers facilitate the detection of achromatic targets on gray and colored backgrounds, but tend to suppress the detection of chromatic targets. Chromatic inducers facilitate the detection of chromatic targets on gray and colored backgrounds, but tend to suppress the detection of achromatic targets. Chromatic spatial facilitation appears to be strongest when inducers and background are isoluminant. The results of a second experiment show that spatial facilitation with chromatic targets and inducers requires a longer exposure duration of the inducers than spatial facilitation with achromatic targets and inducers, which is already fully effective at an inducer exposure of 30 ms only. The findings point towards two separate mechanisms for spatial facilitation with collinear form stimuli: one that operates in the domain of luminance, and one that operates in the domain of color contrast. These results are consistent with neural models of boundary and surface formation which suggest that achromatic and chromatic visual cues are represented on different cortical surface representations that are capable of selectively attracting attention. Multiple copies of these achromatic and chromatic surface representations exist corresponding to different ranges of perceived depth from an observer, and each can attract attention to itself. Color and contrast differences between inducing and test stimuli, and transient responses to inducing stimuli, can cause attention to shift across these surface representations in ways that sometimes enhance and sometimes interfere with target detection. (shrink)

A detection task was performed using different pictographic representations of objects in order to test the hypothesis that high-level information (familiarity) may influence detection thresholds. The stimuli were five versions of forms: outline drawings of objects, silhouettes, and three fragmented versions of forms derived from the outlines. The stimuli varied on two parameters: their nameability (easily nameable, hardly nameable, and not nameable) as assessed by a naming task, and their energy content as assessed by a two-dimensional fast-Fourier transform. The greatest (...) amount of energy was observed for silhouettes, and the amount of energy contained in the vertical and horizontal spatial frequency components was equivalent for outlines and the three versions of fragmented forms. Luminance thresholds for the detection of the forms were measured by means of an adaptive method. The results show that thresholds were determined only by the energy content of the stimuli. High-level semantic or name information had no influence on the detectability of the visual signal. The results are discussed in terms of the visibility of spatial frequency components at detection threshold. (shrink)

The main focus of this special issue is on marginality, a multifaceted concept that requires a cross-disciplinary approach. The papers selected here deal with marginality in the formation of the epistemic canon (?the mainstream?) and the production of knowledge in the humanities and social sciences. By employing the vocabulary of marginality (?marginal,? ?margins,? ?luminal,? ?threshold,? as well as dichotomies such as ?minor-major,? ?center-periphery?), we propose a shift from a discussion of the canon in terms of just one category of (...) ?marginals? (a certain race, class, gender etc.) to considering this complex concept in terms of a plurality of players and factors related to marginality broadly defined, some of which have little or nothing to do with power structures and dichotomies. Marginality is thus conceived of as an epistemic category and not as a power status. (shrink)

Brincat and Westheimer [Journal of Neurophysiology 83 (2000) 1900] have reported facilitating interactions in the discrimination of spatially separated target orientations and co-linear inducing orientations by human observers. With smaller gaps between stimuli (short-range effects), facilitating interactions were found to depend on the contrast polarity of the stimuli. With larger gaps (longrange effects), only co-linearity of the stimuli seemed necessary to produce facilitation. In our study, the dependency of facilitating interactions on the intensity (luminance) of line stimuli is investigated (...) by measuring detection thresholds for a target line separated from the end of an inducing line by co-axial gaps ranging from 5 to 200 min of visual arc. We find facilitating interactions between target and inducing orientations, producing short-range and long-range effects similar to those reported by Brincat and Westheimer. In addition, detection thresholds as a function of the co-axial separation between target and inducing line reveal an interaction between the spatial regime of facilitating effects and the luminance of the stimuli. Short-range effects are found to be sensitive to changes in local intensity while long-range effects remain unaffected. (shrink)

In this paper I argue that there is no viable alternative to construing our knowledge and justified belief as resting on a foundation restricted to truths about our internal states. Against Williamson and others I defend the claim that the internal life of a cognizer really does constitute a special sort of cognitive home that is importantly different from the rest of what we think we know and justifiably believe.

Timothy Williamson has recently argued that few mental states are luminous , meaning that to be in that state is to be in a position to know that you are in the state. His argument rests on the plausible principle that beliefs only count as knowledge if they are safely true. That is, any belief that could easily have been false is not a piece of knowledge. I argue that the form of the safety rule Williamson uses is inappropriate, and (...) the correct safety rule might not conflict with luminosity. (shrink)

Using Finsler brane solutions [see details and methods in: S. Vacaru, Class. Quant. Grav. 28:215001, 2011], we show that neutrinos may surpass the speed of light in vacuum which can be explained by trapping effects from gravity theories on eight dimensional (co) tangent bundles on Lorentzian manifolds to spacetimes in general and special relativity. In nonholonomic variables, the bulk gravity is described by Finsler modifications depending on velocity/momentum coordinates. Possible super-luminal phenomena are determined by the width of locally anisotropic brane (...) (spacetime) and induced by generating functions and integration functions and constants in coefficients of metrics and nonlinear connections. We conclude that Finsler brane gravity trapping mechanism may explain neutrino super-luminal effects and almost preserve the paradigm of Einstein relativity as the standard one for particle physics and gravity. (shrink)

Impurism says that practical factors encroach on knowledge. An important version of impurism is called ‘Threshold-Impurism,’ which says that practical factors encroach on the threshold that rational credence must pass in order for one to have knowledge. A prominent kind of argument for Threshold-Impurism is the so-called ‘principle-based argument,’ which relies on a principle of fallibilism and a knowledge-action principle. This paper offers a new challenge against Threshold-Impur- ism. I attempt to show that the two principles (...) Threshold-Impurists are committed to—KJ and Fallibilism—are jointly in tension with a widely-held principle of credence that’s called ‘Truth-Directedness,’ in the sense that the former two principles cannot both apply to those who know the third. This tension constitutes a serious challenge to Threshold-Impurists, because it leaves them two options, both of which are undesirable: denying Truth-Directedness, or accepting Truth-Directedness and accepting that whether KJ and Fallibilism apply to a person depends on whether she knows Truth-Directedness. (shrink)

Despite the prominence of thresholds in theories of distributive justice, there is no general account of what sort of role is played by the idea of a threshold within such theories. This has allowed an ongoing lack of clarity and misunderstanding around views that employ thresholds. In this article, I develop an account of the concept of thresholds in distributive justice. I argue that this concept contains three elements, which threshold views deploy when ranking possible distributions. These elements (...) are (i) the level of the threshold, (ii) what constitutes the value of the threshold, and (iii) how benefits above and below the threshold must be allocated. I highlight three contributions that this particular account of thresholds makes: it clarifies the nature of the shift that occurs at the threshold; it resolves a common misunderstanding about headcount principles; and it shows how the arbitrariness objection can be met. (shrink)

Mental-threshold egalitarianism, well-known examples of which include Jeff McMahan’s two-tiered account of the wrongness of killing and Tom Regan’s theory of animal rights, divides morally considerable beings into equals and unequals on the basis of their individual mental capacities. In this paper, I argue that the line that separates equals from unequals is unavoidably arbitrary and implausibly associates an insignificant difference in empirical reality with a momentous difference in moral status. In response to these objections, McMahan has proposed the (...) introduction of an intermediate moral status. I argue that this move ultimately fails to address the problem. I conclude that, if we are not prepared to give up moral equality, our full and equal moral status must be grounded in a binary property that is not a threshold property. I tentatively suggest that the capacity for phenomenal consciousness is such a property, and a plausible candidate. (shrink)

Binarizing belief aggregation tackles the problem of aggregating individuals’ probabilistic beliefs on logically connected propositions into the group’s binary beliefs. One common approach to associating probabilistic beliefs with binary beliefs would be applying thresholds to probabilities. This paper aims to introduce and classify a range of threshold-based binarizing belief aggregation rules while characterizing them based on different forms of monotonicity and other properties.

The threshold problem is the task of adequately answering the question: “Where does the threshold lie between knowledge and lack thereof?” I start this paper by articulating two conditions for solving it. The first is that the threshold be neither too high nor too low; the second is that the threshold accommodate the significance of knowledge. In addition to explaining these conditions, I also argue that it is plausible that they can be met. Next, I argue (...) that many popular accounts of knowledge cannot meet them. In particular, I lay out a number of problems that standard accounts of knowledge face in trying to meet these conditions. Finally, near the end of this paper, I argue that there is one sort of account that seems to evade these problems. This sort of account, which is called a cluster account of knowledge, says that knowledge is to be accounted for in terms of truth, belief and a cluster of epistemic properties and also that knowledge doesn’t require having all members of the cluster, but merely some subset. (shrink)

Since its appearance over a decade ago, Timothy Williamson's anti-luminosity argument has come under sustained attack. Defenders of the luminous overwhelmingly object to the argument's use of a certain margin-for-error premise. Williamson himself claims that the premise follows easily from a safety condition on knowledge together with his description of the thought experiment. But luminists argue that this is not so: the margin-for-error premise either requires an implausible interpretation of the safety requirement on knowledge, or it requires other equally implausible (...) assumptions. In this paper I bolster the margin-for-error premise against these attacks by recasting Williamson's own two-part defence, the first part intended to work on the assumption that there is no constitutive connection between the phenomenal and the doxastic, and the second intended to work without this assumption. Pace various luminists, I argue that the appeals to safety needed for Williamson's two-part defence are plausible. I also argue that all that is needed to generate the margin-for-error premise from these safety conditions is an empirical assumption about the kinds of creatures we are: that is, creatures whose beliefs are structured by certain dispositions. By recasting the anti-luminosity argument in this way, we can understand what is really at stake in the debate about luminosity: that is, whether we are luminous. (shrink)

Despite the prominence of thresholds and limits in theories of distributive justice, there is no general account of their role within such theories. This has allowed an ongoing lack of clarity and misunderstanding around threshold views in distributive justice. In this thesis, I develop an account of the conceptual structure of such views. Such an account helps understand and characterize threshold views, can subsume what may seem to be different debates about such views under one conceptual header, and (...) can be used to further examine and develop patterns of justice that draw on thresholds. In light of this account, I propose a novel characterization of sufficientarianism which sheds new light on the distinctiveness of sufficientarianism as a distributive principle and on the common objections to sufficientarianism. Moreover, I examine and defend limitarianism, which is the view that people should not have more than a certain amount of wealth. In particular, I argue in favour of limitarianism as a midlevel principle for guiding institutional design and individual actions and, furthermore, as a specification of what a just allocation of wealth requires under epistemic constraints. (shrink)

The Threshold of the Visible World advances a revolutionary new political aesthetic--Kaja Silverman explores the possibilities for looking beyond the restrictive mandates of the self, and the normative aspects of the cultural image-repertoire. She provides a detailed account of the social and psychic forces which constrain us to look and identify in normative ways, and the violence which that normativity implies. Accounting for these phenomena on both a conscious and an unconcious level, Silverman analyzes the psychic and textual conditions (...) under which our "field of vision" can be expanded. The title of this book is taken from Lacan's essay on the mirror stage. In that text, Lacan writes that "the mirror-image would seem to be the threshold of the visible world." He thereby suggests that the visible world has no existence as such until the infant subject has access to an image of self. Lacan intimates that the mirror provides the frame through which one relates to others within the domain of vision, stressing the priority of narcissism and the ego over all other libidinal transactions. The Threshold of the Visible World provides a psychic, social and political specification of Lacan's claim, and most particularly of its implications for the subject's relations to the social other. This is accomplished through examination of the ego, as well as two other categories at the center of Lacan's account of the mirror stage: ideality and identification. This book is an ethical-political project which leads to the re-elaboration of a number of crucial theoretical categories--Silverman offers an account of the bodily ego, of identification, of idealization, of the gaze, of the look, and of the "photographic." The Threshold of the Visible World leads as well to the formulation of a fresh model for conceptualizing sexual, racial and class "difference," and the terms under which it might be dismantled. This book thus seeks to apprehend the field of vision through the frame of a different kind of bodily ego, and discover the pleasures to be derived from corporeal transport. (shrink)

How, and how well, do people switch between exploration and exploitation to search for and accumulate resources? We study the decision processes underlying such exploration/exploitation trade‐offs using a novel card selection task that captures the common situation of searching among multiple resources (e.g., jobs) that can be exploited without depleting. With experience, participants learn to switch appropriately between exploration and exploitation and approach optimal performance. We model participants' behavior on this task with random, threshold, and sampling strategies, and find (...) that a linear decreasing threshold rule best fits participants' results. Further evidence that participants use decreasing threshold‐based strategies comes from reaction time differences between exploration and exploitation; however, participants themselves report non‐decreasing thresholds. Decreasing threshold strategies that “front‐load” exploration and switch quickly to exploitation are particularly effective in resource accumulation tasks, in contrast to optimal stopping problems like the Secretary Problem requiring longer exploration. (shrink)

Application of egalitarian and prioritarian accounts of health resource allocation in low‐income countries have both been criticized for implying distribution outcomes that allow decreasing/undermining health gains and for tolerating unacceptable standards of health care and health status that result from such allocation schemes. Insufficient health care and severe deprivation of health resources are difficult to accept even when justified by aggregative efficiency or legitimized by fair deliberative process in pursuing equality and priority oriented outcomes. I affirm the sufficientarian argument that, (...) given extreme scarcity of public health resources in low‐income countries, neither health status equality between populations nor priority for the worse off is normatively adequate. Nevertheless, the threshold norm alone need not be the sole consideration when a country's total health budget is extremely scarce. Threshold considerations are necessary in developing a theory of fair distribution of health resources that is sensitive to the lexically prior norm of sufficiency. Based on the intuition that shares must not be taken away from those who barely achieve a minimal level of health, I argue that assessments based on standards of minimal physical/mental health must be developed to evaluate the sufficiency of the total resources of health systems in low‐income countries prior to pursuing equality, priority, and efficiency based resource allocation. I also begin to examine how threshold sensitive health resource assessment could be used in the Philippines. (shrink)

A small consortium of philosophers has begun work on the implications of epistemic networks (Zollman 2008 and forthcoming; Grim 2006, 2007; Weisberg and Muldoon forthcoming), building on theoretical work in economics, computer science, and engineering (Bala and Goyal 1998, Kleinberg 2001; Amaral et. al., 2004) and on some experimental work in social psychology (Mason, Jones, and Goldstone, 2008). This paper outlines core philosophical results and extends those results to the specific question of thresholds. Epistemic maximization of certain types does show (...) clear threshold effects. Intriguingly, however, those effects appear to be importantly independent from more familiar threshold effects in networks. (shrink)

This essay tries to demonstrate two distinct but complementary visions to a central theme of Christian faith: humanity’s redemption in the crucified Christ. It will attempt to show how the poetics of Simone Weil (1909–1943) and the poetic art of Georges Rouault (1871–1943) embody different understandings of Christian faith. Considering faith from a philosophical approach, Weil detaches the sufferings of Christ from the totality of salvific history. Viewing faith from the artistic approach, Rouault places the crucified Christ in the context (...) of the history of salvation, including Mary and the Church. Though different from one another, these two visions reveal to us a light in the midst of our dark or suffering existence that makes audible or perceptible the silence of God’s love in Christ that is its source. (shrink)

Suárez’s primary attempt to rethink angelology can be found in the De Angelis. This work is a mighty commentary on the prima pars of Aquinas’ Summa Theologiae (qq. 50-64) which Suárez left to his colleagues after his years in Coimbra (1597-1607), and which was published posthumously in Lyon in 1620. The composition of the text is somewhat stratified and it includes many references to the Disputationes Metaphysicae, but Suárez most likely already started writing it during his years of teaching in (...) Spain and Italy (1575-1597), before 1597. Because of its Thomistic inspiration, the De angelis is a fundamentally theological and doctrinal work, the metaphysical core of which is independently treated in the DM 35, entitled De immateriali substantia creata. In this passage, which is eminently theoretical, Suárez grapples with the most important quaestiones concerning angels under a metaphysical point of view, therein offering one of the most interesting overviews of early modern angelology. In this paper, I will refer especially to the DM 35, a more synthetic and peculiar work, with some reference to De Angelis as well. I will focus especially on sections 1-3 of DM 35, and try to reconstruct Suárez’s views on the following points: a) the cosmological necessity of angels, their rational demonstrability and the possibility of man’s knowing them (sections 1-2); b) the immaterial essence of angels (section 3). (shrink)

In this paper I shall argue that Tim Williamson’s argument for the anti-luminosity of many mental states faces difficult logical, psychological and epistemological problems. From a logical point of view, his argument is correct. However, the contrary argument that says that the anti-luminosity thesis does not necessarily follow from it is also correct. This opens a sceptical scenario. Hence, if Williamson wants to convince us that we should rationally prefer his argument rather than the other, he needs to add considerations (...) that are not merely logical. These are psychological and epistemological in nature. However, none of these considerations is convincing. (shrink)

Matthias Joseph Scheeben has been described as one of the greatest and least read theologians of the modern era. This article provides an overview of his theology of predestination, which remains a significant but little-studied aspect of his thought. Section I offers a general sketch of Scheeben's theology of predestination, employing the chapter on this topic in The Mysteries of Christianity as a primary source. Section II takes a deeper look at Scheeben's theology of predestination through an engagement with relevant (...) sections of his untranslated masterwork, the Dogmatik. This section will highlight Scheeben's relationship to both the de auxiliis controversy and the thought of Thomas Aquinas. Connections between Scheeben's theology of predestination and his other theological positions are noted throughout. (shrink)

Acupuncture, herbs, and bodywork are fast becoming accepted as complements to standard healing methods. This riveting personal story of the unconventional education of an alternative healer provides extraordinary insight into how and why such methods work. Blending Chinese medicine, the martial arts, and Native American knowing, Daniel Santos challenges us to view the body and its healing in an exciting new way.

We tend to want to avoid and ignore our dark or difficult emotions, biases, and tendencies-and we eschew them on a cultural and societal level because they reveal painful, ugly truths. The labeling of darkness as "negative" becomes a collective excuse to justify avoiding everything that makes humans uncomfortable: racism, spiritual bypass, environmental destruction. Welcoming darkness with curiosity and reverence, rather than fear or judgment, enables us to access our innate capacity for compassion and collective healing. In Seeing with the (...) Heart, dharma teacher, shaman, and deep ecologist Deborah Eden Tull asks us to recognize, explore, and engage with the darkness we experience in our lives in order to learn important lessons and tools for bringing awakening, healing, and compassion to ourselves-and to our world. In an age of global uncertainty, Tull presents the radical teaching of endarkenment--that we can only awaken to wholeness through fully embracing the dark. Darkness, she posits, is not the absence of light, but an intrinsic, vital, healing, and restorative aspect of nature. Tull addresses the spiritual, ecological, psychological, and interpersonal ramifications of our bias towards light over dark. She offers a radical path to wholeness that can be found only through learning to embrace the interplay of both darkness and light, within ourselves and within our world. She offers inspiring teachings, meditations, and mindful inquiry questions to integrate into our daily practice an experiential understanding of endarkenment. (shrink)

Categorical perception (CP) is said to occur when a continuum of equally spaced physical changes is perceived as unequally spaced as a function of category membership (Harnad, S. (Ed.) (1987). Psychophysical and cognitive aspects of categorical perception: A critical overview. Cambridge: Cambridge University Press). A common suggestion is that CP for color arises because perception is qualitatively distorted when we learn to categorize a dimension. Contrary to this view, we here report that English speakers show no evidence of lowered discrimination (...) thresholds at the boundaries between blue and green categories even though CP is found at these boundaries in a supra-threshold task. Furthermore, there is no evidence of different discrimination thresholds between individuals from two language groups (English and Korean) who use different color terminology in the blue-green region and have different supra-threshold boundaries. Our participants' just noticeable difference (JND) thresholds suggest that they retain a smooth continuum of perceptual space that is not warped by stretching at category boundaries or by within-category compression. At least for the domain of color, categorical perception appears to be a categorical, but not a perceptual phenomenon. (shrink)

This paper provides an axiomatic analysis of sufficientarian social evaluation. Sufficientarianism has emerged as an increasingly important notion of distributive justice. We propose a class of principles that we label generalized critical-level sufficientarian orderings. The distinguishing feature of our new class is that its members exhibit constant critical levels of well-being that are allowed to differ from the threshold of sufficiency. Our basic axiom assigns priority to those below the threshold, a property that is shared by numerous other (...) sufficientarian approaches. When combined with the well-known strong Pareto principle and the assumption that there be a constant critical level, the axiom implies that the critical level cannot be below the threshold. The main results of the paper are characterizations of our new class and an important subclass. As a final observation, we identify the generalized critical-level sufficientarian orderings that permit us to avoid the repugnant conclusion and the sadistic conclusion, which are known as two fundamental challenges in population ethics. (shrink)

If you believe that there are restrictions on what we as moral agents can do to others, but that these restrictions can give way in the face of competing considerations, then you believe in thresholds for rights. In this dissertation I develop an account of thresholds for rights, in defence of a position which is often stated but rarely explained or defended. I begin with the obvious question: How much needs to be at stake before a right's claim is overridden? (...) ;Less obvious, but equally crucial, are questions about the distribution of the total which needs to be at stake. After developing a framework for answering that question, in subsequent chapters I deal with other factors which may influence our judgements about the overridability of rights' claims, including the numbers and identities of the agents involved. (shrink)