Visual neuroscience before the neuron

Visual neuroscience is considered to be a contemporary concern, based in large part on relating characteristics of neural functioning to visual experience. It presupposes a detailed knowledge of neural activity for which the neuron doctrine is a fundamental tenet. However, long before either the neuron doctrine had been advanced or the nerve cell had been described, attempts were made to estimate the dimensions of nerve fibres from measures of visual resolution. In the seventeenth century, the microscopes of Hooke and van Leeuwenhoek were unable to resolve structures as small as nerves adequately. However, it was not Hooke's microscope that led to an estimate of the dimensions of nerve fibres but his experiments on the limits of visual resolution. Hooke determined that a separation of one minute of arc was the minimum that could normally be seen. Descartes had earlier speculated that the retina consisted of the terminations of fibres of the optic nerve, and that their size defined the limits of what could be seen. Estimates of the diameters of nerve fibres were made on the basis of human visual acuity by Porterfield in 1738; he calculated the diameters of nerve fibres in the retina as one 7200th part of an inch (0.0035 mm), based on the resolution of one minute of arc as the minimum visible. In the same year, Jurin questioned the reliability of such estimates because of variations in visual resolution with different stimuli. The measurement of visual acuity was refined by Mayer in 1755, with dots, gratings, and grids used as stimuli. In the 1830s, Treviranus fused the microscopic and acuity approaches to determine the dimensions of nerve fibres. His indirect estimates of the dimensions of retinal fibres were close to those derived from microscopic observation. However, the suggestion that the retina consisted of terminations of nerve fibres influenced his detailed illustrations of its microscopic structure. Contrary to the situation that obtained after the microscopic structure of the retina had been established, a function of vision (acuity) was used to determine the dimensions of the structures (retinal elements) that were thought to mediate it.     

On abstraction and the doctrine of terms in eighteenth-century philosophy of language

The aim of this paper is to understand why empiricist philosophers of language did not try to refute the Leibniz-Beauzée argument, which questioned the genetical priority of proper names. It is shown that, within the semantic theory which underlies the empiricist doctrine, one may assume that all general terms derive from particular names, while conceding that every proper name can be etymologically traced back to the ancestor of a common noun.     

The concept of free will: philosophy, neuroscience and the law

Various philosophical definitions of free will are first considered. The compatibilist definition, which says simply that acts are freely willed if they are not subject to constraints, is identified as much used in the legal system and essentially impervious to scientific investigation. A middle-ground "incompatibilist" definition, which requires that freely willed acts be consciously initiated, is shown to be relevant to the idea of mens rea and in the author's view not actually incompatible in principle with a fully scientific worldview. Only the strong libertarian definition, which requires that freely willed acts have no physical antecedents whatsoever, makes the existence of free will very hard to swallow scientifically. However, with regard to the middle-ground "incompatibilist" definition, three different lines of scientific experimental evidence are then described, which suggest that, in fact, consciousness is not the real cause of much of what is generally considered as voluntary behavior. Many voluntary actions are initiated preconsciously, with consciousness kept informed only after the neural events leading to the act have begun. It is suggested that a reasonable way of integrating these experimental findings with the idea that persons do have a somewhat more than compatibilist version of free will is to acknowledge explicitly that a person is a mixture of conscious and unconscious components. In this scenario, the mind in mens rea would have to be judged guilty if it contained either conscious or unconscious intentions to perform the guilty act.     

A kinky doctrine of sin

ABSTRACT

Religious and secular groups alike have long marginalized those who practice “kinky sex.” These discourses of bodily control have been deconstructed and proven faulty. However, this proposal goes further than mere deconstruction and exposes the gaping hole under this new deconstruction: what does a doctrine of sin look like for kink practitioners? This gaping hole is lubed and ready to be filled. According to a kinky doctrine, sin is violating consent and obstructing escape, the failure to accept limits, and the external essentialism of identity. This kinky theology of sin will not only be useful for members of the kink community but also for individuals from a wide range of identities and practices.     

A neuroscience model of stuttering

Using motor control systems analysis and a reductionist approach, we provide a unified model of stuttering. This model views stuttering as a momentary instability in a complex multiloop control system. The model predicts the temporal conditions under which this instability will occur. Furthermore, these temporal conditions account for the efficacy of fluency-evoking maneuvers, therapy, and the variability of speech output in stutterers.     

A critique of causality in Islamic philosophy

After the problems of epistemology, the most fundamental problem of Islamic philosophy is that of causality. Causality has been studied from various perspectives. This paper endeavors first to analyze the issues of causality in Islamic philosophy and then to critique them. A sketch is provided of the history of the development of theories of causality in Islamic philosophy, with particular attention to how religious considerations came to determine the shape of the philosophical theories that were accepted. It is suggested that outstanding philosophical and theological problems that have plagued the tradition of Islamic philosophy require a new approach to the issue of causality.