Pure Time Preference: Reply to Johansson and Rosenqvist

Johansson and Rosenqvist reject our argument for the rational permissibility of pure time preferences (PTP). Johansson and Rosenqvist's main objection is that where two options, X and Y, have equal intrinsic value, there will be a reason to be indifferent between X and Y, and therefore a reason to not hold a PTP for X or Y. In this reply, we argue that if two options have equal intrinsic value, it does not follow that you have a reason to be indifferent. Rather, the two equally large intrinsic values cancel each other out, like two equal weights on kitchen scales.     

Tradition,Authority, and Immanent Critique in Comparative Ethics

Drawing on resources from pragmatist thought allows religious ethicists to take account of the central role traditions play in the formation and development of moral concepts without thereby espousing moral relativism or becoming traditionalists. After giving an account of this understanding of the concept of tradition, I examine the ways in which understandings of tradition play out in two contemporary examples of tradition‐based ethics: works in comparative ethics of war by James Turner Johnson and John Kelsay. I argue that a pragmatist approach to tradition‐based ethics allows for a nuanced and flexible understanding of moral traditions, and one that holds great promise for international consensus‐building around shared ethical norms for the use of armed force.     

Anatomy of a flash. 2. The 'width' of a temporal edge.

In a previous study it has been found by using the Crawford masking paradigm with spatially coextensive stimuli that the end points of even a weak flash have a strong masking effect on the probe pulse, but no threshold elevation was observed when the probe was 100 ms or longer from flash onset and offset. The relationship between the strength of a temporal edge (eg the amplitude of a sudden increase in field luminance) and the duration of masking has not been systematically investigated. In the present experiments the duration of masking produced by a step of luminance as a function of step size was measured. With steps whose amplitude was between ten and five hundred times detection threshold, the duration of masking was about constant, ie 70 and 50 ms for on-responses and off-responses, respectively. This refractory period defined the 'width' of a temporal edge. Unless two suprathreshold unidirectional luminance changes are separated by an interval exceeding the width of a temporal edge, they are perceived as a single change in brightness. A linear systems analysis led to predictions for ramp stimuli that were confirmed by experiment.