Perceptual Reasons and Defeat

Author(s):  
Mark Schroeder

Perceptual evidence about the external world is paradigmatically defeasible. If something looks red to you, it is reasonable to believe that it is red, but if you are wearing rose-tinted glasses, it may not be reasonable at all to believe this, unless you have some independent source of evidence. In this paper, I will compare four models for how to understand this phenomenon. These models differ in their answers to two questions: what evidence we get about the external world through perception, and what our having that evidence consists in. I like one of these models better than the others, but in this paper my primary concern will be to compare their virtues and vices.

Author(s):  
Natasha Warner ◽  
Daniel Brenner ◽  
Jessamyn Schertz ◽  
Andrew Carnie ◽  
Muriel Fisher ◽  
...  

AbstractScottish Gaelic is sometimes described as having nasalized fricatives (/ṽ/ distinctively, and [f̃, x̃, h̃], etc. through assimilation). However, there are claims that it is not aerodynamically possible to open the velum for nasalization while maintaining frication noise. We present aerodynamic data from 14 native Scottish Gaelic speakers to determine how the posited nasalized fricatives in this language are realized. Most tokens demonstrate loss of nasalization, but nasalization does occur in some contexts without aerodynamic conflict, e.g., nasalization with the consonant realized as an approximant, nasalization of [h̃], nasalization on the preceding vowel, or sequential frication and nasalization. Furthermore, a very few tokens do contain simultaneous nasalization and frication with a trade-off in airflow. We also present perceptual evidence showing that Gaelic listeners can hear this distinction slightly better than chance. Thus, instrumental data from one of the few languages in the world described as having nasalized fricatives confirms that the claimed sounds are not made by producing strong nasalization concurrently with clear frication noise. Furthermore, although speakers most often neutralize the nasalization, when they maintain it, they do so through a variety of phonetic mechanisms, even within a single language.


Author(s):  
David James Barnett

According to a traditional Cartesian epistemology of perception, perception does not provide one with direct knowledge of the external world. Instead, your immediate perceptual evidence is limited to facts about your own visual experience, from which conclusions about the external world must be inferred. Cartesianism faces well-known skeptical challenges. But this chapter argues that any anti-Cartesian view strong enough to avoid these challenges must license a way of updating one’s beliefs in response to anticipated experiences that seems diachronically irrational. To avoid this result, the anti-Cartesian must either license an unacceptable epistemic chauvinism, or else claim that merely reflecting on one’s experiences defeats perceptual justification. This leaves us with a puzzle: Although Cartesianism faces problems, avoiding them brings a new set of problems.


Reasons First ◽  
2021 ◽  
pp. 101-124
Author(s):  
Mark Schroeder

Chapter 5 takes up the question of which way of developing a non-factive answer to what evidence perceptual experiences provide about the external world is most promising. Two forms of the apparent defeasibility of knowledge are introduced: objective defeat and subjective defeat. Each view’s resources for accounting for both objective and subjective defeat are compared, and it is argued that the non-factive content view fails to account for both objective and subjective defeat. In contrast, the apparent factive attitude view, because of its closer relationship to disjunctivist alternatives, is argued to offer clean treatments of both objective and subjective defeat—even better than the disjunctivist alternatives from which it borrows. The distinctive commitments of the apparent factive attitude view are defended, its distinctive treatment of the bootstrapping problem for dogmatism is introduced, and the resulting view is contrasted with Matthew McGrath’s objective looks theory.


Author(s):  
Cevito Wilson

Nothing is better than attempting to transform people by boosting their knowledge and improve their living conditions. In Africa and especially in Togo, Elderly people, Artist Painters and Fishermen even though they would like to contribute to their country’s development by their everyday hard-work, are not emerging. Government is not helping and their activities lack efficiency, proper management and appropriate internal communication and with the external world. This is the reason why the ICT in particular People.net, the knowledge charity infrastructure’s potential are proposed as a solution. Communities and various economic sectors could then reinforce their capacity by acquiring the proper knowledge they lack. However, a systemic approach should be considered by the introduction of an efficient and all stakeholders or users accepted ergonomic approach in order to boost the usability of the proposed People.net platform.


1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.


Author(s):  
J. Frank ◽  
P.-Y. Sizaret ◽  
A. Verschoor ◽  
J. Lamy

The accuracy with which the attachment site of immunolabels bound to macromolecules may be localized in electron microscopic images can be considerably improved by using single particle averaging. The example studied in this work showed that the accuracy may be better than the resolution limit imposed by negative staining (∽2nm).The structure used for this demonstration was a halfmolecule of Limulus polyphemus (LP) hemocyanin, consisting of 24 subunits grouped into four hexamers. The top view of this structure was previously studied by image averaging and correspondence analysis. It was found to vary according to the flip or flop position of the molecule, and to the stain imbalance between diagonally opposed hexamers (“rocking effect”). These findings have recently been incorporated into a model of the full 8 × 6 molecule.LP hemocyanin contains eight different polypeptides, and antibodies specific for one, LP II, were used. Uranyl acetate was used as stain. A total of 58 molecule images (29 unlabelled, 29 labelled with antl-LPII Fab) showing the top view were digitized in the microdensitometer with a sampling distance of 50μ corresponding to 6.25nm.


Author(s):  
J. Silcox

In this introductory paper, my primary concern will be in identifying and outlining the various types of inelastic processes resulting from the interaction of electrons with matter. Elastic processes are understood reasonably well at the present experimental level and can be regarded as giving information on spatial arrangements. We need not consider them here. Inelastic processes do contain information of considerable value which reflect the electronic and chemical structure of the sample. In combination with the spatial resolution of the electron microscope, a unique probe of materials is finally emerging (Hillier 1943, Watanabe 1955, Castaing and Henri 1962, Crewe 1966, Wittry, Ferrier and Cosslett 1969, Isaacson and Johnson 1975, Egerton, Rossouw and Whelan 1976, Kokubo and Iwatsuki 1976, Colliex, Cosslett, Leapman and Trebbia 1977). We first review some scattering terminology by way of background and to identify some of the more interesting and significant features of energy loss electrons and then go on to discuss examples of studies of the type of phenomena encountered. Finally we will comment on some of the experimental factors encountered.


Author(s):  
A. V. Crewe

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.


Author(s):  
Li Li-Sheng ◽  
L.F. Allard ◽  
W.C. Bigelow

The aromatic polyamides form a class of fibers having mechanical properties which are much better than those of aliphatic polyamides. Currently, the accepted morphology of these fibers as proposed by M.G. Dobb, et al. is a radial arrangement of pleated sheets, with the plane of the pleats parallel to the axis of the fiber. We have recently obtained evidence which supports a different morphology of this type of fiber, using ultramicrotomy and ion-thinning techniques to prepare specimens for transmission and scanning electron microscopy.


Author(s):  
P.R. Swann ◽  
A.E. Lloyd

Figure 1 shows the design of a specimen stage used for the in situ observation of phase transformations in the temperature range between ambient and −160°C. The design has the following features a high degree of specimen stability during tilting linear tilt actuation about two orthogonal axes for accurate control of tilt angle read-out high angle tilt range for stereo work and habit plane determination simple, robust construction temperature control of better than ±0.5°C minimum thermal drift and transmission of vibration from the cooling system.


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