 Such putative counterexamples are not all on the same level. Although they all violate the letter of  (C),  some could be more easily reconciled with productivity and systematicity than others. If it turned out that in order to interpret an embedded sentence, one needs information about the embedding sentence as well we would have to conclude that the algorithm for calculating the meanings of complex expressions is more complicated then we thought. But a complicated algorithm is still an algorithm and the core explanation of how we understand complex expressions would remain untouched. By contrast, if it turned out that in order to interpret a sentence we must know all sorts of ephemeral non-linguistic facts we would have to conclude that the fact that we can reliably understand all sorts of unfamiliar sentences is a mystery. Those who accept putative counterexamples of this latter kind must provide alternative explanations for productivity and systematicity.