The loss or absence of vision is probably one of the most incapacitating events that can befall a human being. The importance of vision for humans is also reflected in brain anatomy as approximately one third of the human brain is devoted to vision. It is therefore unsurprising that throughout history many attempts have been undertaken to develop devices aiming at substituting for a missing visual capacity. In this review, we present two concepts that have been prevalent over the last (...) two decades. The first concept is sensory substitution, which refers to the use of another sensory modality to perform a task that is normally primarily sub-served by the lost sense. The second concept is cross-modal plasticity, which occurs when loss of input in one sensory modality leads to reorganization in brain representation of other sensory modalities. Both phenomena are training-dependent. We also briefly describe the history of blindness from ancient times to modernity, and then proceed to address themeansthat have been used to help blind individuals, with an emphasis on modern technologies, invasive (various type of surgical implants) and non-invasive devices. With the advent of brain imaging, it has become possible to peer into the neural substrates of sensory substitution and highlight the magnitude of the plastic processes that lead to a rewired brain. Finally, we will address the important question of the value and practicality of the available technologies and future directions. (shrink)

Popper's short essay about the rationality principle has been the target of many criticisms which have raised serious doubts about its consistency. How could the well-known promoter of falsificationism suggest that we not reject a principle that he himself describes as false? Nonetheless, the essay can be read in a way that makes it appear much more consistent. Better sense can be made of Popper's own examples (the flustered driver, the pedestrian, etc.), by taking seriously his view that the rationality (...) principle might be "approximately true" and falsified only in very rare cases, while also giving proper attention to his four rather elliptical arguments. (shrink)

The age of a relational structure R is the set A of finite restrictions of R considered up to isomorphism. R. Fraı̈ssé, who introduced this notion, showed that ages coincide with nonempty ideals of the poset consisting of finite relational structures, considered up to isomorphism and ordered by embeddability. Here, given two ages A ⊆ B , we study the poset D consisting of ages C in sandwich between A and B . Among other things we show that if D (...) is infinite then it contains an infinite chain. (shrink)

This is a basic work for students specializing in philosophy & for any scholar studying the works of Sartre.