  Cartesians respond by pointing out the limitations shown by animals in such studies (they can't play a good game of chess, after all, let alone tell us what they are thinking about), and they join linguists in protesting that the subjects of animal-language studies have not fully mastered the recursive syntax of natural human languages.[7]  But this kind of post hoc raising of the bar suggests to many scientists that the Cartesian position is not being held as a scientific hypothesis, but as a dogma to be defended by any means. Convinced by evidence of sophisticated cognitive abilities, most philosophers these days agree with Block that something like access consciousness is properly attributed to many animals.  Nevertheless, when it comes to phenomenal consciousness, dissimilarity arguments are not entirely powerless to give some pause to defenders of animal sentience, for surely most would agree that, at some point, the dissimilarities between the capacities of humans and the members of another species (the common earthworm Lumbricus terrestris, for example) are so great that it is unlikely that such creatures are sentient. A grey area arises precisely because no one can say how much dissimilarity is enough to trigger the judgment that sentience is absent.