"If you claim that the sky is blue but not colored, you’re not just saying something false — you are showing that you don’t have the relevant concepts (“blue” and “colored”) at all. At a minimum, you are violating your rational obligations. Anyone’s ability to mean anything is made possible by social practices that hold people to such rational rules of entailment and incompatibility. This approach, in Brandom’s formulations, owes much to Kant and, especially, Wittgenstein.
"The question of whether a certain sentence is true, for Brandom, is inseparable from rational standards about what it is permissible or obligatory to say or believe."
To me, this seems to be putting the cart before the horse, as if the truth of a statement is dependent on its linguistic properties. In practice, it seems to me that usage and semantics are bent to a language-independent (but imperfectly perceived) reality rather than the other way around.
Towards the end of the article, its author writes this, which strikes me as being to the point, at least with respect to the relationship between language and reality:
"Brandom’s position, in addition, is overweeningly rationalistic; I am not convinced that my obligation to believe of a blue thing that it is not also chartreuse is, all things considered, much like my obligation not to hurt people for no good reason. That is, the 'deontic' status of rational norms is fundamentally an assumption rather than a result, something that is supposed to be self-evident or entailed by our existing practices. But if I (like the arch anti-Hegelian Søren Kierkegaard, for example) resolve to embrace a paradox, or if I am simply indifferent to certain rational implications of what I already believe, how could we show this to be 'impermissible'? I’ll believe what I like, thank you very much."