 This defines disability colloquially, in terms of ability; disability is, roughly, an unusual inability. Barnes and others object, however, that this definition is too broad. It seems to make it the case, for instance, that someone who cannot “roll their tongue” or do mental subtraction is disabled; since most people can do this under favorable conditions. Conversely, this sort of view also seems to undergenerate disabilities, since some (fibromyalgia or depression for instance), only make it more difficult to do things, without making any particular task or function straightforwardly unachievable. And it is not entirely clear how this account avoids the obviously problematic implication that identity categories like race, gender, and sexual orientation imply disability; someone subject to social prejudice in virtue of their gender or the color of their skin might be, for that reason, unable to do things others can do.