This paper explores the relationship between propositional existence and the ontological status of fictional entities. It questions whether a proposition asserting the existence of fictional entities can truly exist. Through the analysis of the logical structure of existential propositions and their truth conditions, we explore whether a proposition like "Unicorns exist" can be meaningful within a strict logical framework. By integrating Quine’s theory of ontological commitment and Russell’s theory of descriptions, we argue that the existence of a proposition does not (...) necessarily entail the existence of its subject but instead its coherence within a logical system. We also present a thought experiment to illustrate the implications of fictional entities within classical logic and examine whether introducing a third truth value — "undefined" or "unknown" — challenges the law of excluded middle. (shrink)

When dissimilar images are presented to the two eyes, binocular rivalry (BR) occurs, and perception alternates spontaneously between the images. Although neural correlates of the oscillating perception during BR have been found in multiple sites along the visual pathway, the source of BR dynamics is unclear. Psychophysical and modeling studies suggest that both low- and high-level cortical processes underlie BR dynamics. Previous neuroimaging studies have demonstrated the involvement of high-level regions by showing that frontal and parietal cortices responded time locked (...) to spontaneous perceptual alternation in BR. However, a potential contribution of early visual areas to BR dynamics has been overlooked, because these areas also responded to the physical stimulus alternation mimicking BR. In the present study, instead of focusing on activity during perceptual switches, we highlighted brain activity during suppression periods to investigate a potential link between activity in human early visual areas and BR dynamics. We used a strong interocular suppression paradigm called continuous flash suppression to suppress and fluctuate the visibility of a probe stimulus and measured retinotopic responses to the onset of the invisible probe using functional MRI. There were ∼130-fold differences in the median suppression durations across 12 subjects. The individual differences in suppression durations could be predicted by the amplitudes of the retinotopic activity in extrastriate visual areas (V3 and V4v) evoked by the invisible probe. Weaker responses were associated with longer suppression durations. These results demonstrate that retinotopic representations in early visual areas play a role in the dynamics of perceptual alternations during BR. (shrink)