Our goal is to understand human language use and create systems that can use human language fluently. We argue that to a achieve this goal, we must formulate all of the problems for language use from morphology up to pragmatics using the same cognitive substrate of reasoning and representation abilities. We propose such a substrate and described systems based on it. Our arguments, results with real-world systems and ongoing work suggest that the cognitive substrate enables a significant advance in the power of cognitive models and intelligent systems to use human language.