If Friedman is right that the world is "flat," we need to understand the linguistic implications of that claim. In this increasingly flat world, classical critical literacy is both urgently needed and poorly understood from a linguistic perspective. Three claims based on research on reading can improve both the understanding of the common psycholinguistic features of literacy and the practice of critical literacy: The first claim is that in this flat world, psycholinguistic research on literacy shows that humans' underlying abilities are constant from page to screen, drawing on basic cognitive and linguistic processing mechanisms including recognition, identification, categorization and others. The second claim is that literacy is the highest level in the on-going evolution of human language abilities. Finally, the third claim states that the forms of literacy are evolving in new media across digital and linguistic borders of all kinds. Psycholinguistic research provides a deeper understanding of and evidence for all three claims. This paper explores the implications of these claims for literacy in a flat world.