Multiple realization in cognitive neurorehabilitation research.

I argue that cognitive neurorehabilitation is currently faced with important challenges for its progress. Whereas most challenges are already well-known and debated in the field, a relatively overlooked challenge is whether cognitive functions are multiply realized. I argue that this debate is central to progress in cognitive neurorehabilitation. I conclude arguing that progress is possible but requires methodological improvements to determine how and not just if a function is rehabilitated, and methods to decide whether two instances of a cognitive function are identical. The aim of this article is therefore twofold: first, to demonstrate why the question of multiple realization is not an abstract philosophical curiosity but a methodological bottleneck for research in cognitive neurorehabilitation, and-second - to suggest directions for empirical innovation that can help resolve whether observed recovery reflects restoration, compensation, or genuine multiple realization.